Re: How to use the returned telnet object after creating the telnet session.

[Denis McMahon]

On Sun, 13 Sep 2015 00:38:03 -0700, manjunatha.mahalingappa wrote:

> Assume that I will pass IP and port information from a function to open
> the telnet session. have opened the telnet session and after opening the
> telnet session I returned telnet object to calling function.
> 
> Now in the calling function If I use that object to read or write to
> terminal I'm getting ERROR "AttributeError: 'NoneType' object has no
> attribute 'read_very_eager'".

My best guess would be that something failed and has returned None 
instead of the object / class you're expecting.

-- 
Denis McMahon, denismfmcma...@gmail.com
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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

New submission from Serhiy Storchaka:

Added this issue as a place for discussion and release blocker for 3.5.

--
assignee: yselivanov
components: Documentation
messages: 250549
nosy: larry, serhiy.storchaka, yselivanov
priority: release blocker
severity: normal
status: open
title: Editing What's New In Python 3.5
versions: Python 3.5

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Re: Terminology: "reference" versus "pointer"

[Jussi Piitulainen]

Random832 writes:
> Jussi Piitulainen writes:
>> I think the best way is to say that a[0] and a[1] are the same
>> object, while b[0] and b[1] are different objects.
>
> Sure, you can *say* that. But how do you draw it on a diagram with
> sticky notes or parcel tags or whatever?

I prefer to outline my code as code, with comments where needed, without
irrelevant details. Those pointers and tags are usually irrelevant, best
omitted altogether.
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How to use the returned telnet object after creating the telnet session.

[manjunatha . mahalingappa]

Hello all,

First I would like thank you for creating such good platform for discussing 
python..!!!

Assume that I will pass IP and port information from a function to open the 
telnet session. have opened the telnet session and after opening the telnet 
session I returned telnet object to calling function.

Now in the calling function If I use that object to read or write to terminal 
I'm getting ERROR "AttributeError: 'NoneType' object has no attribute 
'read_very_eager'".


#Open telnet connection to devices

def open_telnet_conn(dname,ip,port):

try:
TELNET_PORT = port
TELNET_TIMEOUT = 5
READ_TIMEOUT = 5
cmd = "show config"
#Logging into device

connection=telnetlib.Telnet(ip, TELNET_PORT, TELNET_TIMEOUT)

time.sleep(1)
connection.write(cmd + "\n")

#Here I'm able to write to connection object..
connection.write("\n")
time.sleep(2)

router_output = connection.read_very_eager()
print router_output

return(connection)

except IOError:

print "Input parameter error! Please check username, password and file 
name."


#Function to read device IP and port . and this info for opening the telnet 
session.
def IP_port(file):
T = []
F = open(file,'r')
F.seek(0)

line=F.read()
tuples = re.findall(r'(.+?)\s+(.+?)\s+(\d+)',line)

#(dname,IP,port)= tuples

for (dname,ip,port) in tuples:
T1=open_telnet_conn(dname,ip,port)
#HERE I will get the telnet object point to the same location as the 
connection object. But I'm unable to write or read anything here. I think need 
to convert the object T1 to TELNET CLASS object type..

print T1
T1.write("show config") https://mail.python.org/mailman/listinfo/python-list

[issue25082] Editing What's New In Python 3.5

[Larry Hastings]

Larry Hastings added the comment:

You wait until the day of release for 3.5.0 final, then create a "release 
blocker" because some items in the What's New documentation aren't 
lexographically sorted?

We tagged the release yesterday.  The installers are already built.  I am not 
holding up the release for this.

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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

Personally I found few interesting Python 3.5 features just reading recent 
commit log for Doc/whatsnew/3.5.rst. Without this they would be unknown for me.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Alexander Belopolsky]

On Sat, Sep 12, 2015 at 9:58 PM, Tim Peters  wrote:

> > That's why I believe PEP 495 followed by the implementation
> > of fold-aware "as intended" tzinfos (either within stdlib or by third
> > parties) is the right approach.
>
> Me too - except I think acceptance of 495 should be contingent upon
> someone first completing a fully functional (if not releasable)
> fold-aware zoneinfo wrapping.


Good idea.  How far are you from completing that?


>   Details have a way of surprising, and
> we should learn from the last time we released a tzinfo spec in the
> absence of any industrial-strength wrappings using it.


I completely agree.  That's why I am adding test cases like Lord Hope
Island and Vilnius to datetimetester.

I will try to create a  zoneinfo wrapping prototype as well, but I will
probably "cheat" and build it on top of pytz.
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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

Sorry, but I thought that such issue already exist.

Yury and Elvis made a lot of changes in What's New in few last days and 
continue to edit it. Are these changes included in 3.5.0 final? Without their 
What's New just isn't ready.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Alexander Belopolsky]

On Sat, Sep 12, 2015 at 6:24 PM, Guido van Rossum  wrote:

> The repeated claims (by Alexander?) that astimezone() has the power of
> pytz's localize() need to stop.


Prove me wrong! :-)


> Those pytz methods work for any (pytz) timezone -- astimezone() with a
> default argument only works for the local time zone.


That's what os.environ['TZ'] = zonename is for.  The  astimezone() method
works for every timezone installed on your system.  Try it - you won't even
need to call time.tzset()!


> (And indeed what it does is surprising, except perhaps to pytz users.)


That I agree with.  Which makes it even more surprising that I often find
myself and pytz advocates on the opposite sides of the fence.

Granted, setting TZ is a silly trick, but one simple way to bring a full TZ
database to Python is to allow .astimezone() take a zonename string like
'Europe/Amsterdam' or 'America/Montevideo' as an argument and act as
os.environ['TZ'] = zonename; t.astimezone() does now, but without messing
with global state.

I made this suggestion before, but I find it inferior to "as intended"
tzinfos.

The only real claim that I am making is that fictitious fixed offset
timezones are useful and we already have some support for them in stdlib.
The datetime.timezone instances that .astimezone() attaches as tzinfo are
not that different from the instances that are attached by pytz's localize
and normalize methods.

In fact, the only major differences between datetime.timezone instances and
those used by pytz is that pytz's EST and EDT instances know that they come
from America/New_York, while datetime.timezone instances don't.  That's why
once you specify America/New_York in localize, your tzinfo.normalize knows
it implicitely, while in the extended .astimezone() solution you will have
to specify it again.  This is not a problem when you only support one local
timezone, but comes with a different set of tradeoffs when you have
multiple timezones.

One advantage of not carrying the memory of the parent zoneinfo in the
fixed offset tzinfo instance is that pickling of datetime objects and their
interchange between different systems becomes simpler.  A pickle of a
datetime.timezone instance is trivial - same as that of a tuple of
timedelta and a short string, but if your fixed offset tzinfo carries a
reference to a potentially large zoneinfo structure, you get all kinds of
interesting problems when you share them between systems that have
different TZ databases.

In any case, there are three approaches to designing a TZ database
interface in the datetime module: the "as intended" approach, the pytz
approach and the astimezone(zonename:str) approach.  The last two don't
require a fold attribute to disambiguate end-of-dst times and the first one
does.  With respect to arithmetic, the last two approaches are equivalent:
both timeline and classic arithmetics are possible, but neither is
painless.  The "as intended" approach comes with classic arithmetic that
"just works" and encourages the best practice for timeline arithmetic: do
it in UTC.  That's why I believe PEP 495 followed by the implementation of
fold-aware "as intended" tzinfos (either within stdlib or by third parties)
is the right approach.
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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Alexander Belopolsky]

On Sat, Sep 12, 2015 at 10:25 PM, Tim Peters  wrote:

> > I will try to create a  zoneinfo wrapping prototype as well, but I will
> > probably "cheat" and build it on top of pytz.
>
> It would be crazy not to ;-)  Note that Stuart got to punt on "the
> hard part":  .utcoffset(), since pytz only uses fixed-offset classes.
> For a prototype - and possibly forever after - I'd be inclined to
> create an exhaustive list of transition times in local time, parallel
> to the list of such times already there in UTC.


Yes.  The only complication is that you need four transition points instead
of two per year in a regular DST case: (1) start of gap; (2) end of gap;
(3) start of fold; and (4) end of fold.  Once you know where you are with
respect to those points, figuring out utcoffset(), dst() and tzname() for
either value of fold is trivial.


>   An index into either
> list then gives an index into the other, and into the list of
> information about the transition (total offset, is_dst, etc).


Right.

It's a shame though to work from a transitions in UTC list because most of
DST rules are expressed in local times and then laboriously converted into
UTC.  I think I should also implement the POSIX TZ spec tzinfo.  This is
where the advantage of the "as intended" approach will be obvious.
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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

Some modules in the "Improved Modules" section are out of lexicographic order: 
csv, ssl.

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Trac 1.0.9 released

[Ryan Ollos]

Trac 1.0.9 Released
===

Trac 1.0.9, the latest maintenance release for the
current stable branch, is available.

You will find this release at the usual places:

  http://trac.edgewall.org/wiki/TracDownload#LatestStableRelease
  https://pypi.python.org/pypi/Trac/1.0.9

Trac 1.0.9 provides more than a dozen minor fixes
and enhancements, including significantly reduced
memory usage by the Git repository connector.

You can find the detailed release notes for 1.0.9
on the following pages:
  http://trac.edgewall.org/wiki/TracDev/ReleaseNotes/1.0#MaintenanceReleases

Now to the packages themselves:

URLs:

  http://download.edgewall.org/trac/Trac-1.0.9.tar.gz
  http://download.edgewall.org/trac/Trac-1.0.9.win32.exe
  http://download.edgewall.org/trac/Trac-1.0.9.win-amd64.exe
  http://download.edgewall.org/trac/Trac-1.0.9.zip

MD5 sums:

429d9aa79e3d939add7963ca9a7deb57  Trac-1.0.9.tar.gz
9801dbb0b93d22294d82ad7cc2d33829  Trac-1.0.9.win32.exe
db1c35aa95fda539e6b7365fb5af4780  Trac-1.0.9.win-amd64.exe
0bb8ceffe7dbe6211a3887e42a1be972  Trac-1.0.9.zip

SHA1 sums:

a22c4f648c2f0adf7ca166aa5c01b0142bccbef0  Trac-1.0.9.tar.gz
caa4d0c96a456c8a9427c9bd0db8d665b911d50a  Trac-1.0.9.win32.exe
3a82ccc0fdf3dc8ca9077cb3432464a3ff2547e6  Trac-1.0.9.win-amd64.exe
ac338b2fde74df9ab19948d1caf6d25cc0e37622  Trac-1.0.9.zip


Acknowledgements


Many thanks to the growing number of people who
have, and continue to, support the project. Also
our thanks to all people providing feedback and bug
reports that helps us make Trac better, easier to
use and more effective. Without your invaluable help,
Trac would not evolve. Thank you all.

Finally, we offer hope that Trac will prove itself
useful to like-minded programmers around the world,
and that this release will be an improvement over
the last version.

Please let us know.

/The Trac Team  http://trac.edgewall.org/
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Support the Python Software Foundation:
http://www.python.org/psf/donations/

Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[random832]

On Sat, Sep 12, 2015, at 22:25, Tim Peters wrote:
> That helps a lot, but "industrial-strength" implies "by algorithm".
> There are far too many zones to deal with by crafting a hand-written
> class for each.

It occurs to me that though it's written in C, the zdump utility
included in the tz code is implementation-agnostic w.r.t. what algorithm
is used by the localtime function being tested. It's algorithm could
probably be adapted to python.
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Re: RPI.GPIO Help

[John McKenzie]

 Hello, there.

 MRAB, thank you for teaching me proper Python syntax for how I tried to 
use the or operator.

 Dennis, I must have learned allot recently as I believe I understood 99% 
of that code. I see how it is not just more advanced, but actually better 
than what I had. However, line 47 (cumTime[colour] += now - changeTime) 
had an error I could not figure out what to do about. Considering my time 
line I decided not to leave it to latter. Will be using these electronic 
flags at next year's game and for then I intend to just be better about 
everything. Will use your code to learn to get there.

 Hakugin, thank you you as well. I took the basic ideas you showed me for 
improvement and used them. The pulse settings variable was not liked by 
the interpreter, so I simplified it. I turned it into a hex value for 
each button press, then in the main loop I inserted the whole line for 
the LED pulse command, but put "pulse_settings" after "hex=" in the 
arguments. This worked.

 I added a few green blinks of the LED to indicate the starting and 
stopping of the script. Also, I got the log files score print outs upon 
exit working. Very important, and also importantly, I have it so it stops 
after a certain amount of time. For testing, I have it at 60 seconds, but 
games will be 3600 seconds on average when really being used.

 The stopping after a certain amount of time was done in a way that 
apparently technically works, but seems very weird and probably wrong to 
me. You may freak out when you see it. I used an else statement inside a 
while loop and it just feels so strange. At least it works.

 Hoping I might be able to make it so I boot the Pi, it loads the script, 
script waits for the user to tell it how long to make a game, game 
starts, scripts ends game at appropriate time, saves dated log file with 
scores, then waits for user to enter new game length to start new game. 
This is probably way to much to hope to accomplish in time. For next year 
for sure though. It would be better for the referees to operate that way.

 Next I will try and integrate wireless communications. If anyone here 
knows Synapse RF modules well, or at all, PLEASE contact me.


 Here is the code I did up most recently. Again, thanks for all the 
suggestions, code examples, and general help.

import atexit
import sys
import time 
from blinkstick import blinkstick 
import RPi.GPIO as GPIO   

gamestart = time.time()
gamelength = 60

led = blinkstick.find_first() 
colour = 0
time_red = 0
time_yellow = 0
time_blue = 0
timestamp = time.strftime("%H:%M:%S")
pulse_settings = []

led.blink(name="green", repeats=2)

GPIO.setmode(GPIO.BCM)
GPIO.setup(22, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(24, GPIO.IN, pull_up_down=GPIO.PUD_UP)


def red_button(channel):
global colour
global pulse_settings
if colour != 1:
colour = 1
pulse_settings = "#FF"

def yellow_button(channel):
global colour
global pulse_settings
if colour != 2:
colour = 2
pulse_settings = "#FF8900" # Corrected yellow for cheap LED strip.

def blue_button(channel):
global colour
global pulse_settings
if colour != 3:
colour = 3
pulse_settings = "#FF"


GPIO.add_event_detect(22, GPIO.FALLING, callback=red_button, 
bouncetime=200)
GPIO.add_event_detect(23, GPIO.FALLING, callback=yellow_button, 
bouncetime=200)
GPIO.add_event_detect(24, GPIO.FALLING, callback=blue_button, 
bouncetime=200)

def exit_handler():
print "\033[0;41;37mRed Team:\033[0m ", time_red
print "\033[0;103;30mYellow Team:\033[0m ", time_yellow
print "\033[0;44;37mBlue Team:\033[0m ", time_blue
flog = open("flag1.log", "a")
flog.write("\n" + timestamp + "\n" + "Red Team: " + str(time_red) + 
"\n" + "Yellow Team: " + str(time_yellow) + "\n" + "Blue Team: " + str
(time_blue) + "\n")
flog.close()
led.blink(name="green", repeats=4)
led.set_color(name="black")
atexit.register(exit_handler)


while time.time() < gamestart + gamelength:
if colour == 1:
time_red += 1
elif colour == 2:
time_yellow += 1
elif colour == 3:
time_blue += 1
led.pulse(hex=pulse_settings, repeats=1, duration=2000, steps=50)
time.sleep(0.1)
else:
sys.exit()

GPIO.cleanup()




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Re: Terminology: "reference" versus "pointer"

[Steven D'Aprano]

On Sun, 13 Sep 2015 10:50 pm, Steven D'Aprano wrote:

> On Sun, 13 Sep 2015 04:45 am, ru...@yahoo.com wrote:
... ^


> But as I said to Rurpy, 

Er, that would be you.

Editing fail. Sorry about that.


-- 
Steven

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[issue25087] Type variable substitution in type instances

[Stefan Krah]

New submission from Stefan Krah:

If a type scheme is instantiated, should the type variables in the
class body be substituted?  This is an example (typed by hand on
a locked down Windows machine, may contain errors):


alpha = TypeVar('alpha')
beta = TypeVar('beta')

class ABTuple(Generic[alpha, beta]):
def __init__(self, a : alpha, b : beta):
self.value = (a, b)

get_type_hints(ABTuple.__init__)
 ==> {'b': ~beta, 'a': ~alpha}


IntIntTuple = ABTuple[int, int]

IntIntTuple
 ==> __main__.ABTuple[int, int]

get_type_hints(IntIntTuple.__init__)
{'b': ~beta, 'a': ~alpha}
  ^^  ^^


Since the type has been specialized, these should ideally be 'int'.

--
components: Interpreter Core
messages: 250565
nosy: gvanrossum, skrah
priority: normal
severity: normal
status: open
title: Type variable substitution in type instances
type: behavior
versions: Python 3.5

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Integration using scipy odeint

[sagar k]

Dear all 

I'm using Python 3.4.3. I am facing a problem in integrating using odeint 
solver. In the following code, tran is a function and in those are the 
variables which are arrays. These variables change their values with respect to 
time (the time which I pass to the function). I tried defining a loop inside 
the function, but Python throws an error saying float object not iterable. 
Please guide me how to solve this problem. 

#initial is an array containing initial values for the integration, dt is the 
time array with unequal time steps, which I have captured from other part of 
the code

def tran(initial,dt):
for i in dt:
k1 [i] = 2.8e8 * math.exp(-21100/ta[i]) # k1,k2,k3 & k4 are constants 
which change according to temperature (ta), which in turn changes with respect 
to time. 
k2 [i] = 1.4e2 * math.exp(-12100/ta[i]) # ta changes its values 
according to dt, which is array. It runs from 0-6 with unequal time steps.
k3 [i] = 1.4e5 * ta[i] * math.exp(-19680/ta[i]) # I've captured dt and 
all other arrays here from another loop, which is not of importtance.
k4 [i] = 1.484e3 * ta[i]
y = initial[0]
z = initial[1]
dn = (6*rho*initial[1])
dd = (math.pi*2000*initial[0])
ds = (dn/dd)**1/3
dydt = (166.2072*ta[i]*cca[i] - (1.447e13 * ta[i]**0.5 * rho**1/6 * 
y**1/6 * rho**1/6 * z**1/6 * 0.0832)) # cca,ta are arrays. y & z are 2 
dependent variables
dzdt = (k1[i]*ta[i]*cca[i]*12.011 + (21.2834*k2[i]*ta[i]*cca[i] * 
y**1/2 *ds) - (k3[i]*ta[i]*12.011*y*math.pi*ds**2 * cco[i]) -
(phi*k4[i]*ta[i]*xo[i]*12.011*y*math.pi*ds**2))
return [dydt,dzdt] # dydt & dzdt are my final time integrated values

initial = [0.01,1e-5]
sol = odeint(tran, initial, dt) #this is my function call

If I pass array in my function call, it says only length-1 can be converted to 
Python scalars.

So I request all the experts in the group to tell me where I'm going wrong.

Regards
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[issue25082] Editing What's New In Python 3.5

[Stefan Behnel]

Stefan Behnel added the comment:

Thanks, Yury!

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Phone Tree

[Azureaus]

Hi,
I'm helping out some teenagers (14yo ish) who have just started programming and 
are working on a 'call tree' program as part of some after school coding 
classes and I wanted to talk about potential solutions. 

The first task is to implement a 'troubleshooting program' similar to what a 
phone operator would have when you phone up with a problem. We all know the 
type when you phone up your ISP, 'have you turned it off and on again?', "have 
you changed your telephone filter' etc..

It states there should be at least 10 questions and that the user should reach 
a solution, e.g. 'replace your power cable'. There and my initial reaction was 
that this could be achieved by lots of if/else statements with each question 
running onto another one, ugly but it would certainly work. One of them pointed 
out how inefficient this was and asked if there was another way, they hated 
writing out tons of if/elif/else statements.

Does anyone have any ideas for a more elegant solution? My thoughts are that I 
could use a tree data structure and hence make traversing the tree recursive 
based on yes or no answers. I'm happy to put the time in to explain these more 
complex ideas, I'm just hoping those with more expertise than myself could 
either help verify the idea or suggest alternatives.

Thanks in advance!
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[issue25082] Editing What's New In Python 3.5

[Elvis Pranskevichus]

Elvis Pranskevichus added the comment:

Larry, it looks like the "Detailed Release Information" link on the release 
page still points to rc3, which is a 404 now.

Also, there doesn't seem to be a link to the "What's new" document, only a 
Misc/NEWS link.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Tim Peters]

[Alex]
>>I will try to create a  zoneinfo wrapping prototype as well, but I will
>>probably "cheat" and build it on top of pytz.

[Laura Creighton]
> My question, is whether it will handle Creighton, Saskatchewan, Canada?
> Creighton is an odd little place.  Like all of Saskatchewan, it is
> in the Central time zone, even though you would expect it to be
> in the Mountain time zone based on its location on the globe.
> The people of Saskatchewan have decided not to adopt Daylight
> Savings time.  Except for the people of Creighton (and
> nearby Denare Beach) -- who _do_ observe Daylight savings time.
>
> makes for an interesting corner case, one that I remember for
> personal (and not economic, or professional) reasons.

Hi, Laura!  By "zoneinfo" here, we mean the IANA (aka "Olson") time
zone database, which is ubiquitous on (at least) Linux:

https://www.iana.org/time-zones

So "will a wrapping of zoneinfo handle XYZ?" isn't so much a question
about the wrapping as about what's in the IANA database.

Best guess is that Creighton's rules are covered by that database's
America/Winnipeg entries.  It's generally true that the database makes
no attempt to name every location on the planet.  Instead it uses
names of the form "general/specific" where "general" limits the scope
to some large area of the Earth (here "America" really means "North
America"), and "specific" names a well-known city within that area.

For example, I live in Ashland, Wisconsin (extreme far north in that
state, on Lake Superior), but so far as IANA is concerned my time zone
rules are called "America/Chicago" (some 460 air miles SSE, in a
different state).

Just for fun, I'll paste in the comments from the Saskatchewan section
of IANA's "northamerica" data file (a plain text source file from
which binary tzfiles like America/Chicago and America/Winnipeg are
generated).  You'll see Creighton mentioned if you stay alert ;-)

# Saskatchewan

# From Mark Brader (2003-07-26):
# The first actual adoption of DST in Canada was at the municipal
# level.  As the [Toronto] Star put it (1912-06-07), "While people
# elsewhere have long been talking of legislation to save daylight,
# the city of Moose Jaw [Saskatchewan] has acted on its own hook."
# DST in Moose Jaw began on Saturday, 1912-06-01 (no time mentioned:
# presumably late evening, as below), and would run until "the end of
# the summer".  The discrepancy between municipal time and railroad
# time was noted.

# From Paul Eggert (2003-07-27):
# Willett (1914-03) notes that DST "has been in operation ... in the
# City of Moose Jaw, Saskatchewan, for one year."

# From Paul Eggert (2006-03-22):
# Shanks & Pottenger say that since 1970 this region has mostly been as Regina.
# Some western towns (e.g. Swift Current) switched from MST/MDT to CST in 1972.
# Other western towns (e.g. Lloydminster) are like Edmonton.
# Matthews and Vincent (1998) write that Denare Beach and Creighton
# are like Winnipeg, in violation of Saskatchewan law.

# From W. Jones (1992-11-06):
# The. . .below is based on information I got from our law library, the
# provincial archives, and the provincial Community Services department.
# A precise history would require digging through newspaper archives, and
# since you didn't say what you wanted, I didn't bother.
#
# Saskatchewan is split by a time zone meridian (105W) and over the years
# the boundary became pretty ragged as communities near it reevaluated
# their affiliations in one direction or the other.  In 1965 a provincial
# referendum favoured legislating common time practices.
#
# On 15 April 1966 the Time Act (c. T-14, Revised Statutes of
# Saskatchewan 1978) was proclaimed, and established that the eastern
# part of Saskatchewan would use CST year round, that districts in
# northwest Saskatchewan would by default follow CST but could opt to
# follow Mountain Time rules (thus 1 hour difference in the winter and
# zero in the summer), and that districts in southwest Saskatchewan would
# by default follow MT but could opt to follow CST.
#
# It took a few years for the dust to settle (I know one story of a town
# on one time zone having its school in another, such that a mom had to
# serve her family lunch in two shifts), but presently it seems that only
# a few towns on the border with Alberta (e.g. Lloydminster) follow MT
# rules any more; all other districts appear to have used CST year round
# since sometime in the 1960s.

# From Chris Walton (2006-06-26):
# The Saskatchewan time act which was last updated in 1996 is about 30 pages
# long and rather painful to read.
# http://www.qp.gov.sk.ca/documents/English/Statutes/Statutes/T14.pdf
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[issue25082] Editing What's New In Python 3.5

[Yury Selivanov]

Yury Selivanov added the comment:

And can we point https://docs.python.org/3/ to 3.5 docs?

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[issue25082] Editing What's New In Python 3.5

[Yury Selivanov]

Yury Selivanov added the comment:

Larry,

Please rebuild the documentation, we've pushed the last round of edits in 
746add37495c.

Also, could you please merge 3.5 into default -- I don't know how to resolve 
some conflicts after your 3.5.0 -> 3.5 merge.

> I could add a "What's New" link somewhere.

Thanks for adding it! Can we make it a bit more prominent by moving it to the 
top of the page?  PEP links are important, but what's new is more digestible.

Stefan, I've added a link to your package.

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[issue25082] Editing What's New In Python 3.5

[Larry Hastings]

Larry Hastings added the comment:

I don't know how to do it.  I asked the Documentation Expert member of the 
Python 3.5 release team, but it seems he's afk at the moment.  I'm trying to 
find someone else who knows how to do it.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Laura Creighton]

In a message of Sun, 13 Sep 2015 10:27:30 -0500, Tim Peters writes:
>Hi, Laura!  By "zoneinfo" here, we mean the IANA (aka "Olson") time
>zone database, which is ubiquitous on (at least) Linux:
>
>https://www.iana.org/time-zones
>
>So "will a wrapping of zoneinfo handle XYZ?" isn't so much a question
>about the wrapping as about what's in the IANA database.

Then we had better be able to override it when it is wrong.

>Best guess is that Creighton's rules are covered by that database's
>America/Winnipeg entries.

># Saskatchewan
># Other western towns (e.g. Lloydminster) are like Edmonton.
># Matthews and Vincent (1998) write that Denare Beach and Creighton
># are like Winnipeg, in violation of Saskatchewan law.

I think that this will work.
Creighton is just across the border from Flin Flan, Manitoba.  Indeed I think
the problem of 'drunken people from Manitoba trying to get one hours more
drinking done and being a menace on the highway' may have fueled the
'we are going to have DST in violation of the law' movement in Creighton.

But I am not sure how it is that a poor soul who just wants to print a
railway schedule 'in local time' is supposed to know that Creighton is
using Winnipeg time.

Laura


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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

ssl should be between sqlite3 and subprocess.

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Re: Python handles globals badly.

[Steven D'Aprano]

On Sun, 13 Sep 2015 10:04 pm, Skybuck Flying wrote:

> "
> Namespaces don't "become writeable".
> 
> The purpose of "global" is to tell the compiler that this name should
> be bound in the global namespace, not the local namespace.
> "
> 
> How does it become writeable then ?

It's always writeable.






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[issue25082] Editing What's New In Python 3.5

[Stefan Behnel]

Stefan Behnel added the comment:

Could I get a little note in the collections.abc section that the new ABCs 
"Generator", "Coroutine" and "Awaitable" are available as backports in the 
"backports_abc" package on PyPI?

https://pypi.python.org/pypi/backports_abc

I'd like to prevent others from innocently feeling a needless need to roll 
their own solution.

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[issue25088] scipy (0.16.0) install fails on 3.5

[Naveen Togar]

New submission from Naveen Togar:

SciPy install using pip fails with the following error:

Running from scipy source directory.

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/numpy/distutils/system_info.py:594:
 UserWarning: Specified path /usr/local/include/python3.5m is invalid.
  warnings.warn('Specified path %s is invalid.' % d)

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/numpy/distutils/system_info.py:594:
 UserWarning: Specified path /usr/include/python3.5m is invalid.
  warnings.warn('Specified path %s is invalid.' % d)
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
"object of type 'type' has no len()" in evaluating 'len(list)' (available 
names: [])
error: library dfftpack has Fortran sources but no Fortran compiler found


Command "/Library/Frameworks/Python.framework/Versions/3.5/bin/python3.5 -c 
"import setuptools, 
tokenize;__file__='/private/var/folders/jg/dd63x6c54t9g3qcr2c1xk968gn/T/pip-build-kb3aqu9u/scipy/setup.py';exec(compile(getattr(tokenize,
 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" 
install --record 
/var/folders/jg/dd63x6c54t9g3qcr2c1xk968gn/T/pip-dljex650-record/install-record.txt
 --single-version-externally-managed --compile" failed with error code 1 in 
/private/var/folders/jg/dd63x6c54t9g3qcr2c1xk968gn/T/pip-build-kb3aqu9u/scipy

I didn't have any issues on Python 3.4.  I am on OS X Yosemite.

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components: Installation
messages: 250573
nosy: ntogar
priority: normal
severity: normal
status: open
title: scipy (0.16.0) install fails on 3.5
type: compile error
versions: Python 3.5

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Re: Python handles globals badly.

[Skybuck Flying]

"
Namespaces don't "become writeable".

The purpose of "global" is to tell the compiler that this name should
be bound in the global namespace, not the local namespace.
"

How does it become writeable then ?

Bye,
 Skybuck.
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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Laura Creighton]

In a message of Sat, 12 Sep 2015 22:15:02 -0400, Alexander Belopolsky writes:
>I completely agree.  That's why I am adding test cases like Lord Hope
>Island and Vilnius to datetimetester.
>
>I will try to create a  zoneinfo wrapping prototype as well, but I will
>probably "cheat" and build it on top of pytz.

My question, is whether it will handle Creighton, Saskatchewan, Canada?
Creighton is an odd little place.  Like all of Saskatchewan, it is
in the Central time zone, even though you would expect it to be
in the Mountain time zone based on its location on the globe.
The people of Saskatchewan have decided not to adopt Daylight
Savings time.  Except for the people of Creighton (and
nearby Denare Beach) -- who _do_ observe Daylight savings time.

makes for an interesting corner case, one that I remember for
personal (and not economic, or professional) reasons.

Laura

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[issue25082] Editing What's New In Python 3.5

[Roundup Robot]

Roundup Robot added the comment:

New changeset aa288ad94089 by Yury Selivanov in branch '3.5':
whatsnew/3.5: Fix typo (issue #25082)
https://hg.python.org/cpython/rev/aa288ad94089

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[issue25082] Editing What's New In Python 3.5

[Larry Hastings]

Larry Hastings added the comment:

I'm hoping to release 3.5.0 final in the next hour or two.  I don't want to 
hold up the release for your changes.  However, when you're done making changes 
to the document, and they're all checked in, let me know and I'll manually 
build it and push it to the web site.

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[issue25085] Windows x86-64 embeddable zip file contains test directorys

[Wolfgang Langner]

New submission from Wolfgang Langner:

The Windows x86-64 embeddable zip file (and possible the one for 32bit)
includes some unnecessary test folders in python35.zip with test scripts.

python35.zip\distutils\tests\
python35.zip\unittest\test\
python35.zip\lib2to3\tests\
python35.zip\ctypes\test\
python35.zip\sqlite3\test\

Python Version 3.5 rc4

This is only a minor issue, because it affects only size not functionality.

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messages: 250563
nosy: paul.moore, steve.dower, tds333, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Windows x86-64 embeddable zip file contains test directorys
type: enhancement
versions: Python 3.5

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[issue25086] Windows x86-64 embeddable zip file, lot of big EXE files in distuils

[Wolfgang Langner]

New submission from Wolfgang Langner:

In the Windows x86-64 embeddable zip file in
python35.zip\distutils\command\
are a lot of big EXE files. Possible during build for different
VC compilers.

I don't know the exact structure but thing there should only be EXE's
for the actual used compiler to build Python.

But there are:

wininst-10.0-amd64.exe
wininst-10.0.exe
wininst-14.0-amd64.exe
wininst-14.0.exe
wininst-6.0.exe
wininst-7.1.exe
wininst-8.0.exe
wininst-9.0-amd64.exe
wininst-9.0.exe

These files are really big, and some or all? possible not needed for
and embeddable zip distributed Python.

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messages: 250564
nosy: dstufft, eric.araujo, paul.moore, steve.dower, tds333, tim.golden, 
zach.ware
priority: normal
severity: normal
status: open
title: Windows x86-64 embeddable zip file, lot of big EXE files in distuils
type: enhancement
versions: Python 3.5

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Re: Phone Tree

[Chris Angelico]

On Mon, Sep 14, 2015 at 12:39 AM, Azureaus  wrote:
> The first task is to implement a 'troubleshooting program' similar to what a 
> phone operator would have when you phone up with a problem. We all know the 
> type when you phone up your ISP, 'have you turned it off and on again?', 
> "have you changed your telephone filter' etc..
>
> It states there should be at least 10 questions and that the user should 
> reach a solution, e.g. 'replace your power cable'. There and my initial 
> reaction was that this could be achieved by lots of if/else statements with 
> each question running onto another one, ugly but it would certainly work. One 
> of them pointed out how inefficient this was and asked if there was another 
> way, they hated writing out tons of if/elif/else statements.
>
> Does anyone have any ideas for a more elegant solution? My thoughts are that 
> I could use a tree data structure and hence make traversing the tree 
> recursive based on yes or no answers. I'm happy to put the time in to explain 
> these more complex ideas, I'm just hoping those with more expertise than 
> myself could either help verify the idea or suggest alternatives.
>

This sounds broadly similar to a Twenty Questions game. You may be
able to find some neat implementations of that, which could be
reworked into what you want.

A more cynical algorithm could be implemented as follows:

import random
questions = [
# The IT Crowd
"Hello, IT, have you tried turning it off and on again?",
# The Bastard Operator From Hell
"How long has this been happening?",
"Has anyone else had this problem?",
"Is it your floor that has the Gas Leak?",
# Standard ISP questions
"Have you tried disabling your antivirus?",
"Are we talking to the authorized account holder?",
# Add additional questions as required
]
random.shuffle(questions)
questions = questions[::2] # Ask about half of them
for q in questions:
response = input(q) # raw_input in Py2
# Utterly ignore the response
print("I'm sorry, nobody else has reported this problem, so it cannot
be a real problem.")

I may or may not be basing this on real life experience.

For something a bit more useful, though, what you might have is a
nested pile of tuples. For instance:

questions = (
# First the question
"Have you rebooted your computer?",
# Then the if-no response
"Please reboot your computer, then call back.",
# Finally the if-yes response
("Are you running Windows?",
("Are you using a Macintosh?",
"I'm sorry, we only support Windows and Mac OS.",
"Let me transfer you to our Macintosh support people.",
),
("Have you disabled your antivirus?",
"Please disable your AV and try again.",
("Is it your floor that has the gas leak?",
"I'm sorry, I can't help you.",
"Strike a match. All your problems will disappear.",
),
),
),
)

while isinstance(questions, tuple):
q, no, yes = questions
response = input(q)
if response == "yes": questions = yes
elif response == "no": questions = no
else: print("I'm sorry, I didn't understand that response.")
print(questions) # is now the solution

This is a data-driven algorithm. The code is extremely short, and is
fundamentally about the UI; you could change it completely (a GUI app,
text-to-speech and DTMF for IVR, etc, etc) without changing the
question structure at all.

Is this the kind of tree structure you had in mind?

ChrisA
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Re: Terminology: "reference" versus "pointer"

[Chris Angelico]

On Mon, Sep 14, 2015 at 1:31 AM, rurpy--- via Python-list
 wrote:
> Ben,
>
> If the troll being taunted here is referring to me, I suggest
> you review my posts in this thread,  You've said in the past
> that you don't read posts from Google Groups (that's fine,
> your choice) so perhaps you do not have a clear idea what I
> have written.

I think Ben's referring to taunting jmf, whom Mark called the "RUE" or
"Resident Unicode Expert". There has been a long-standing antagonism
between those two (which is completely understandable), and one which
often spills over into vitriolic posts (which is less acceptable).

ChrisA
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Re: Terminology: "reference" versus "pointer"

[Steven D'Aprano]

On Sun, 13 Sep 2015 04:45 am, ru...@yahoo.com wrote:

> On 09/12/2015 10:32 AM, Steven D'Aprano wrote:
>> On Sat, 12 Sep 2015 02:42 pm, Random832 wrote:
>>[...]
>> Computer science and IT is *dominated* by a single usage for "pointer" --
>> it's an abstract memory address. The fundamental characteristics of
>> pointers are:
> 
> Just upthread, you claimed something was "universally agreed"

I did? "Universially agreed" doesn't sound like something I would say. Do
you have a link to where I said that?

I think you're confusing me with somebody else. Somebody who is not me.



[...]
>> Python, Java, Ruby, Lua, Javascript etc. have *no such concept* as
>> pointer. There are no values in these languages which correspond to the
>> standard definition of pointer:
> 
> They have not such concept because the developers and documentors choose
> not to describe that language that way. That does not mean one could not
> come up with a perfectly valid description that did include the concept
> of pointers.

I have little problem with you using "pointer" as a metaphor: "Python
variables are like pointers in these ways...". I do have a problem with you
insisting that they are pointers.

You can, if you choose, decide to change the meaning of the word "pointer".
After all, as a general English term, it just means a type of dog. No,
wait, that's the wrong meaning. It means anything which points in some
fashion, like a dog.

But as I said to Rurpy, if you're going to insist on using your own meanings
for words, the onus is on you to ensure that people aren't going to
misunderstand you. Sure, you could insist that `x = math.sin(1)` makes x a
string, and justify that piece of obnoxious linguistic trickery by saying
that x is a string of bits, but I think that we'd be justified in objecting
to that misuse of terminology.

Sure, you can insist that `x = math.sin(1)` makes x a pointer, but that too
is a misuse of terminology.

You can continue to call Python variables "pointers". After all, language is
a construct, and words have no meaning but that we give them, and there is
no law that says you are forbidden from using your own private meaning of
words. And when you do, I shall continue to object vehemently to your
wilful malapropism.


[...]
> It may not be appropriate way to describe Python for everybody but
> it is perfectly reasonable (and even preferable) for people with
> an understanding of "pointers" from some other language. And for
> those people who don't then one could argue they are a clean slate
> and using the word "pointer" won't hurt.

No, it is not reasonable. 

You want to insist that `x = 23` in Python code makes x a pointer. But that
Python snippet is analogous to to the following C and Pascal snippets:

# C
int x = 23;


{Pascal}
var x: integer;
begin 
  x := 23;
end;


Do you insist that they are pointers to? Then everything is a pointer, and
the word has no meaning. 

Regardless of which of the three languages we are talking about, the
assignment `x = 23` does not mean "bind some value to x which, when
dereferenced, gives the value 23". The value bound to x is 23, not some
indirect pointer to 23.

The *implementation* of how names and variables are bound may (or may not)
involve pointers, but that is outside of the language abstraction, whether
we are talking about Python, C or Pascal.

To call x a pointer to 23 breaks the language abstraction and confuses the
(optional) implementation for the language interface:

* CPython's implementation of namespaces may include a hash table, 
  where the table's values are pointers to objects in the heap;

* C's and Pascal's implementation of variables may include a 
  compile-time table of variable names mapped to memory addresses;

All three implementations may include a "thing-which-points" (Python name
bindings may involve C pointers to objects implemented as C structs; Pascal
and C variables may involve a compile-time table that points to the memory
address of the variable being accessed), but NONE of them justifies calling
x a pointer in ANY of those languages. 

If it helps you understand Python's programming model to discuss the
implementation, by all means do so. But be clear that you are talking about
*implementation* and not Python code.



-- 
Steven

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[issue24665] CJK support for textwrap

[Florent Gallaire]

Changes by Florent Gallaire :


Added file: http://bugs.python.org/file40451/CJK+fix.patch

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[RELEASED] Python 3.5.0 is now available

[Larry Hastings]

On behalf of the Python development community and the Python 3.5 release 
team, I'm proud to announce the availability of Python 3.5.0.  Python 
3.5.0 is the newest version of the Python language, and it contains many 
exciting new features and optimizations.



You can read all about what's new in Python 3.5.0 here:

   https://docs.python.org/3.5/whatsnew/3.5.html


And you can download Python 3.5.0 here:

   https://www.python.org/downloads/release/python-350/

Windows and Mac users: please read the important platform-specific 
"Notes on this release" section near the end of that page.



We hope you enjoy Python 3.5.0!


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Re: Terminology: "reference" versus "pointer"

[rurpy--- via Python-list]

On 09/12/2015 08:42 PM, Ben Finney wrote:
> Michael Torrie  writes:
>> On 09/12/2015 08:22 PM, Mark Lawrence wrote:
>>> You appear to have the same level of knowledge of Python internals as 
>>> the RUE has of the Python 3.3+ FSR unicode implementation.  Let's have 
>>> some fun, is Python pass by value or pass by reference?  It has to be 
>>> more interesting debating that than the drivel that's gone before in 
>>> this thread.
>>
>> Oh you are a devious one there! This should get good.
>
> No, it should stop there. Taunting trolls is no more welcome here than
> trolling.

Ben,

If the troll being taunted here is referring to me, I suggest 
you review my posts in this thread,  You've said in the past 
that you don't read posts from Google Groups (that's fine, 
your choice) so perhaps you do not have a clear idea what I 
have written.

One of the most effective ways for a community to discredit 
itself is to make accusations of trolling in response to 
unpopular but legitimate and reasonable opinion.

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xlwings v0.4.0 adds reliable support for multiple instances on Windows

[Felix Zumstein]

I am pleased to announce the release of xlwings v0.4.0: 

The most important update with this release was made on Windows: The 
methodology used to make a connection to Workbooks has been completely 
replaced. This finally allows xlwings to reliably connect to multiple instances 
of Excel even if the Workbooks are opened from untrusted locations (network 
drives or files downloaded from the internet). This gets rid of the dreaded 
"Filename is already open..." error message that was sometimes shown in this 
context. It also allows the VBA hooks ("RunPython") to work correctly if the 
very same file is opened in various instances of Excel.

Check the Release Notes for full details: 
http://docs.xlwings.org/whatsnew.html 

About xlwings: 
xlwings is a BSD-licensed python library that makes it easy to call python from 
Excel and vice versa: 

Interact with Excel from python using a syntax that is close to VBA yet 
pythonic. 
Replace your VBA macros with python code and still pass around your workbooks 
as easily as before. 
xlwings fully supports NumPy arrays and Pandas DataFrames. 

It works with Microsoft Excel on Windows and Mac. 

http://xlwings.org
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Re: Python handles globals badly.

[Skybuck Flying]

"Steven D'Aprano"  wrote in message 
news:55f566c8$0$1644$c3e8da3$54964...@news.astraweb.com...


On Sun, 13 Sep 2015 10:04 pm, Skybuck Flying wrote:


"
Namespaces don't "become writeable".

The purpose of "global" is to tell the compiler that this name should
be bound in the global namespace, not the local namespace.
"

How does it become writeable then ?


"
It's always writeable.
"

Thus my logic is correct.

By making something global, it ends up in the global namespace, and it 
becomes writeable.


I don't even understand how python interpreter works but I can understand it 
better than you guys do apperently hahaha.


Bye,
 Skybuck. 


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Re: Python handles globals badly.

[Skybuck Flying]

I may add to that:

Just like most programmers don't truely understand what a compiler does ! 
HAHAHAHAHA.


C programmers, Delphi programmers, Java programmers.

What python's interpreter is doing same thing, probably completely 
irrelevant.


Except when it comes to making changes to how python works ;)

I don't need to know how the Python interpreter works, cause I will never 
change Python's implementation.


However as indicated I did try to help out.

Reversing the logic for python's global functioning should be possible.

Bye,
 Skybuck. 


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[issue25082] Editing What's New In Python 3.5

[Elvis Pranskevichus]

Changes by Elvis Pranskevichus :


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[issue25084] remove semi-busy loop in py2.7 threading.Condition.wait(timeout=x)

[Flavio Grossi]

New submission from Flavio Grossi:

threading.Condition.wait(timeout=x) is implemented in python 2  as a semi-busy 
loop which causes cpu wakeups and unexpected cpu use.

I think this is somewhat problematic since it causes problems in all modules 
which use that method, such as Queue.get() when used with a timeout.

This issue has been reported and "fixed" in red hat based distributions in a 
way which i find problematic, as detailed here:
https://bugzilla.redhat.com/show_bug.cgi?id=1230802

The attached patch backports the following change from py3 to fix the problem:
https://hg.python.org/cpython/rev/01d1fd775d16/

--
components: Library (Lib)
files: timedlock.patch
keywords: patch
messages: 250562
nosy: flavio, pitrou
priority: normal
severity: normal
status: open
title: remove semi-busy loop in py2.7 threading.Condition.wait(timeout=x)
type: enhancement
versions: Python 2.7
Added file: http://bugs.python.org/file40450/timedlock.patch

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[issue25082] Editing What's New In Python 3.5

[Larry Hastings]

Larry Hastings added the comment:

The "Detailed Release Information" link is correct.  You probably just have an 
old cached copy of something.

I could add a "What's New" link somewhere.

Though both of these things are interesting, neither of them is relevant to 
this issue.  Maybe you could jump on IRC and report them in real time?

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[RELEASED] Python 3.5.0 is now available

[Larry Hastings]

On behalf of the Python development community and the Python 3.5 release 
team, I'm proud to announce the availability of Python 3.5.0.  Python 
3.5.0 is the newest version of the Python language, and it contains many 
exciting new features and optimizations.



You can read all about what's new in Python 3.5.0 here:

   https://docs.python.org/3.5/whatsnew/3.5.html


And you can download Python 3.5.0 here:

   https://www.python.org/downloads/release/python-350/

Windows and Mac users: please read the important platform-specific 
"Notes on this release" section near the end of that page.



We hope you enjoy Python 3.5.0!


//arry/
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Re: Python handles globals badly.

[Skybuck Flying]

"Emile van Sebille"  wrote in message 
news:mailman.433.1442078406.8327.python-l...@python.org...


On 9/11/2015 10:22 PM, Skybuck Flying wrote:



I didn't learn anything from this posting, sorry ! ;)


"
I'm seeing a pattern here...
"

Only thing I might have learned from him was global namespace make thing 
writeable.


But now somebody else says nope.

So I can truely say nothing was learned.

Explaining concepts to people takes something different.

As far as I am concerned python works with objects like Delphi.

And everything else is a reference to it.

And the globals are somehow protected.

But he's as clueless as everybody else seems to be.

For me it doesn't matter since I will write python code just fine without 
understanding any of it.


Bye,
 Skybuck.


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Re: Python handles globals badly.

[Skybuck Flying]

From what he wrote I can see he's not making much sense...


Neither are you.

Just lot's of nag and little python related stuff.

Bye,
 Skybuck.
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Re: Python handles globals badly.

[Ned Batchelder]

On Sunday, September 13, 2015 at 8:11:13 AM UTC-4, Skybuck Flying wrote:

> I don't even understand how python interpreter works but I can understand it 
> better than you guys do apperently hahaha.

As tempting as it is to respond to Skybuck, with a brief pause to consider,
and a deep breath, I'm sure we can all agree that there is no point in it.

Skybuck: go in peace, and thanks for being part of the Python community.

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[issue25082] Editing What's New In Python 3.5

[Yury Selivanov]

Yury Selivanov added the comment:

> Some modules in the "Improved Modules" section are out of lexicographic 
> order: csv, ssl.

Yes, these two weren't properly ordered by *2nd* letter.  Fixed.

>>-constructor.  All converters defined in config parser (either by subclassing 
>>or

Good catch.  Both Elvis and I are going to do a final thorough pass over the 
whatsnew to fix hiccups like this one.  In no way this should be a release 
blocker.

> Second, if the What's New was really that horribly out of date, and we wanted 
> people who download the documentation to get a fresh one, we could easily 
> update the downloadable documentation; it ships separately.  There would be 
> no need to hold up the release for this.

I'd say it's in a ready shape.  We've spent tons of time refining it, syncing 
NEWS items first, looking for undocumented changes in commits without NEWS 
updates, syncing docs by versionadded/changed (both ways), etc.  I'm fairly 
confident that 99% of changes are now documented.  We'll fix the remaining 
typos/formatting issues in a few hours.

> And finally, I actually backported the What's New in 3.5 to the 3.5.0 release 
> yesterday.

Thanks for doing that, Larry!

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[issue24965] Implement PEP 498: Literal String Formatting

[Yury Selivanov]

Changes by Yury Selivanov :


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[issue25061] Add native enum support for argparse

[paul j3]

paul j3 added the comment:

I'm not quite sure what you mean by 'the enum type to be stored directly'.

With my type function, the string input is converted to an enum object and that 
is stored in the Namespace.  You can't be any more direct than that.

Or are you thinking that `argparse` has some catalog of 'types' that it uses to 
check for value validity and conversion?  There isn't such a collection.  The 
value of the 'type' parameter has to be a callable.  (There is a registry 
mechanism, but that just maps strings on to callables.)

My suggestion does not provide help, but that isn't hard to write that for 
yourself.  A help parameter like:

help='Enum: {%s}'%','.join([t.name for t in CustomEnumType])

would display:

usage: ipython3 [-h] [-p P]

optional arguments:
  -h, --help  show this help message and exit
  -p PEnum: {VAL1,VAL2,VAL3}

For really long lists you could write a multiline help and display it with a 
RAW formatter.

I wouldn't use 'choices' with a type function like this.  The type function 
takes care of all the necessary testing and error messaging.  As you write, 
displaying the enum values would just be confusing.


If we define a dictionary wrapper for the enum class, the use of 'choices' 
might not seem so hacky:

 enumDict = {t.name.lower():t for t in CustomEnumType}
 parser.add_argument("-q", default="val1", choices=enumDict)

 parser.print_help()

producing:

usage: ipython3 [-h] [-p P] [-q {val1,val3,val2}]

optional arguments:
  -h, --help   show this help message and exit
  -p P Enum: {VAL1,VAL2,VAL3}
  -q {val1,val3,val2}

The keys of a 'choices' dictionary are used automatically in the usage and 
help.  That's nice when there are a few choices, but not so good when there are 
many.  Those problems have been discussed in other bug issues.

This dictionary can be used just like your code to convert the Namespace string 
to an enum object:

In [57]: parser.parse_args([])
Out[57]: Namespace(p=, q='val1')
In [58]: enumDict[_.q]
Out[58]: 

And of course 'choices' handles the error listing as well - a plus or minus:

In [59]: parser.parse_args(['-q','test'])
usage: ipython3 [-h] [-p P] [-q {val1,val3,val2}]
ipython3: error: argument -q: invalid choice: 'test' (choose from 'val1', 
'val3', 'val2')
...

If we are going add anything to streamline the handling of 'enums', it should 
also streamline the handling of any mapping.  The main thing that 'enums' adds 
to Python is a uniqueness constraint - which is an insignificant issue in the 
argparse context.  My custom type function would work just as well with a 
dictionary.  And a dictionary would allow the use of aliases, as well as the 
upper/lower tweaking.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Laura Creighton]

In a message of Sun, 13 Sep 2015 15:13:53 -0500, Tim Peters writes:
>[Laura]
>> Via Rail will give you a schedule when you book your tickets.  But I
>> am wrong, it gives it to you in local time, which you can scrape or
>> even use the via rail api.  So it is the person getting off in
>> Creighton who wants to tell his relatives back in Halifax what
>> time he is arriving (in their time) (so they can call him and
>> avoid the hellish hotel surtax on long distance calls) who will
>> have the problem.
>
>Whatever time zone the traveler's railroad schedule uses, so long as
>it sticks to just one

This is what does not happen.  Which is why I have written a python
app to perform conversions for my parents, in the past.

>But there's nothing new here:  datetime has been around for a dozen
>years already, and nobody is proposing to add any new basic
>functionality to tzinfos.  PEP 495 is only about adding a flag to
>allow correct conversion of ambiguous local times (typically at the
>end of DST, when the local clock repeats a span of times) to UTC.  So
>if this were a popular use case, I expect we would already have heard
>of it.  Note that Python zoneinfo wrappings are already available via,
>at least, the pytz and dateutil packages.

I am a happy user of pytz.  On the other hand, I think this means that
my brain has gone through some sort of non-reversible transformation
which makes me accurate, but not exactly sane on the issue.

I think I have misunderstood Alexander Belopolsky as saying that
datetime had functionality which I don't think it has. Thus I thought
we must be planning to add some functionality here.  Sorry about this.

However, people do need to be aware, if they are not already, that
people with 3 times in 3 different tz will want to sort them.  Telling
them that they must convert them to UTC before they do so is, in my
opinion, a very fine idea. Expecting them to work this out by themselves
via a assertion that the comparison operator is not transitive, is,
I think, asking a lot of them.

Laura

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[issue25082] Editing What's New In Python 3.5

[Yury Selivanov]

Yury Selivanov added the comment:

> ssl should be between sqlite3 and subprocess.

It makes sense that ssl module description follows the socket module.

--
resolution:  -> fixed
stage:  -> resolved
status: open -> closed

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[issue25082] Editing What's New In Python 3.5

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

Many thanks to Yury and Elvis for your work on What's New.

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Re: Terminology: "reference" versus "pointer"

[Akira Li]

Random832  writes:

> Akira Li <4kir4...@gmail.com> writes:
>>Rustom Mody  writes:
>>> viz. I have two variables (or names!) say a and b which look the same
>> a
>>> [[1,2],[1,2]]
>> b
>>> [[1,2],[1,2]]
>>> And yet doing
>> a[0][0] = "Oops!"
>>> gives a data structure one "Oops!"
>>> whereas doing it to b mysteriously gives 2
>>
>> Sorry, I haven't followed the whole thread. Could your provide a
>> complete code example? Mention what you expect to happen and what
>> happens instead in your case.
>
> a0 = a1 = [1, 2]
> b0 = [1, 2]
> b1 = [1, 2]
> a = [a0, a1]
> b = [b0, b1]
> del a0, a1, b0, b1
>
> There's nothing about *him* expecting anything wrong to happen. The
> question is how to draw a diagram that unambiguously shows the resulting
> structure using the "parcel tags" model shown in the diagrams (and
> without having a0/a1/etc as actual names)

I'm not sure what "parcel tags" model is but if you mean these
pictures[1] than it works in this case as well as any other (take *a*,
*b* nametags, put them on the corresponding balloons that represents
list objects).

The only names left are *a* and *b* that refer to the corresponding
lists. There is no ambiguity there to put *a*, *b* nametags.

Lists as any other containers contain references to other objects and
therefore "box and arrows" model provides _more details_ here[2,3]

> If the "parcel tags" model can't show it, then the "parcel tag" model
> clearly is not a correct and complete depiction of how Python actually
> works.
> (If I were drawing a picture rather than ASCII I'd add something to make
> it clear that the pairs shown are list objects Like, it's a circle with
> the word "list" and two pointer-boxes inside it.)

"correct and complete" is impossible in the general case for any model.

Imagine what happens if numpy arrays are used instead of Python lists:

  lst = [numpy.array([1, 2]) for _ in range(3)]
  a = [lst[0], lst[0]]
  b = [lst[1], lst[2]]

Note: there could be no a[0][0], a[0][1], etc corresponding Python
objects until you explicitly reference them in the code. If there are no
Python objects then you can't draw any arrows and therefore "box and
arrows" model is incomplete.

Or consider this collections of all Unicode characters:

  class U:
 def __len__(self):
 return sys.maxunicode + 1
 def __getitem__(self, index):
 if index < 0:
 index += len(self)
 if 0 <= index < len(self):
 return chr(index)
 raise IndexError(index)

  u = U()
  print(u[0x61]) # -> a

In this example, it is even more clear that the corresponding items
might not exist until they are explicitly referenced in a program. *u*
is a sequence as any other in Python (it is easy to make it
*collections.abc.Sequence* compatible).

Or this:

  lst = [range(1, 3) for _ in range(3)]
  a = [lst[0], lst[0]]
  b = [lst[1], lst[2]]

In Python 2, it is the exact replica of the original example. In Python
3, it is the same if you don't need to mutate the ranges. Again, the
leaf objects might not exist until you reference them in the code in
Python 3.

Finally, consider a Python sequence that uses os.urandom()
internally. No model will predict the result (and therefore no model is
complete) in this case.


[1]
http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#python-has-names
[2]
http://www.pythontutor.com/visualize.html#code=a0+%3D+a1+%3D+%5B1,+2%5D%0Ab0+%3D+%5B1,+2%5D%0Ab1+%3D+%5B1,+2%5D%0Aa+%3D+%5Ba0,+a1%5D%0Ab+%3D+%5Bb0,+b1%5D%0Adel+a0,+a1,+b0,+b1%0A=display=opt-frontend.js=false=false=false=3=%5B%5D=6
[3]
http://www.pythontutor.com/visualize.html#code=a0+%3D+a1+%3D+%5B1,+2%5D%0Ab0+%3D+%5B1,+2%5D%0Ab1+%3D+%5B1,+2%5D%0Aa+%3D+%5Ba0,+a1%5D%0Ab+%3D+%5Bb0,+b1%5D%0Adel+a0,+a1,+b0,+b1%0Aa%5B0%5D%5B0%5D+%3D+%22Oops!%22=display=opt-frontend.js=false=false=false=3=%5B%5D=7


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Re: Integration using scipy odeint

[Laura Creighton]

In a message of Sun, 13 Sep 2015 07:49:37 -0700, sagar k writes:
>Dear all 
>
>I'm using Python 3.4.3. I am facing a problem in integrating using odeint 
>solver. In the following code, tran is a function and in those are the 
>variables which are arrays. These variables change their values with respect 
>to time (the time which I pass to the function). I tried defining a loop 
>inside the function, but Python throws an error saying float object not 
>iterable. Please guide me how to solve this problem. 
>
>#initial is an array containing initial values for the integration, dt is the 
>time array with unequal time steps, which I have captured from other part of 
>the code
>
>def tran(initial,dt):
>for i in dt:
>k1 [i] = 2.8e8 * math.exp(-21100/ta[i]) # k1,k2,k3 & k4 are constants 
> which change according to temperature (ta), which in turn changes with 
> respect to time. 
>k2 [i] = 1.4e2 * math.exp(-12100/ta[i]) # ta changes its values 
> according to dt, which is array. It runs from 0-6 with unequal time steps.
>k3 [i] = 1.4e5 * ta[i] * math.exp(-19680/ta[i]) # I've captured dt and 
> all other arrays here from another loop, which is not of importtance.
>k4 [i] = 1.484e3 * ta[i]
>y = initial[0]
>z = initial[1]
>dn = (6*rho*initial[1])
>dd = (math.pi*2000*initial[0])
>ds = (dn/dd)**1/3
>dydt = (166.2072*ta[i]*cca[i] - (1.447e13 * ta[i]**0.5 * rho**1/6 * 
> y**1/6 * rho**1/6 * z**1/6 * 0.0832)) # cca,ta are arrays. y & z are 2 
> dependent variables
>dzdt = (k1[i]*ta[i]*cca[i]*12.011 + (21.2834*k2[i]*ta[i]*cca[i] * 
> y**1/2 *ds) - (k3[i]*ta[i]*12.011*y*math.pi*ds**2 * cco[i]) -
>(phi*k4[i]*ta[i]*xo[i]*12.011*y*math.pi*ds**2))
>return [dydt,dzdt] # dydt & dzdt are my final time integrated values
>
>initial = [0.01,1e-5]
>sol = odeint(tran, initial, dt) #this is my function call
>
>If I pass array in my function call, it says only length-1 can be converted to 
>Python scalars.
>
>So I request all the experts in the group to tell me where I'm going wrong.
>
>Regards

You are getting this error, correct?
TypeError: only length-1 arrays can be converted to Python scalars

I don't know anything about odeint.  But when I get these errors it
is because I passed a numpy array into something that wanted a python
list.  This may be what you are doing.

numpy arrays have a tolist method.

see if passing array.tolist() instead of array works for you.

Laura


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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Laura Creighton]

In a message of Sun, 13 Sep 2015 14:00:33 -0500, Tim Peters writes:
>> But I am not sure how it is that a poor soul who just wants to print a
>> railway schedule 'in local time' is supposed to know that Creighton is
>> using Winnipeg time.
>
>I'm not sure how that poor soul would get a railway schedule
>manipulable in Python to begin with ;-)

Via Rail will give you a schedule when you book your tickets.  But I
am wrong, it gives it to you in local time, which you can scrape or
even use the via rail api.  So it is the person getting off in
Creighton who wants to tell his relatives back in Halifax what
time he is arriving (in their time) (so they can call him and
avoid the hellish hotel surtax on long distance calls) who will
have the problem.

And this is the sort of use case I think we will see a lot of.

>Blame politicians for this.  I can assure you Guido is not responsible
>for creating this mess ;-)

:)

Laura

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convert element in a list to float

[forums_mp]

For starters, I googled and saw a plethora of writings on how to convert an 
entire list from string to float.   My interest is on select elements in the 
list.  The output from the print statement: print scenarioList 
  
is as follows

[ '300', '"N"', '1140', '"E"' ]

I need to convert the first and third element to float.  
  lat = ( float ) scenarioList [ 0 ]
  lon = ( float ) scenarioList [ 2 ]

fails (invalid syntax).  How can I achieve my objective. 

Thanks in advance

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Re: How to set the history commands visible ?

[Laura Creighton]

In a message of Sun, 13 Sep 2015 19:15:19 +0200, Glus Xof writes:
>Hi guys,
>
>Today, a new python stable version was released (thanks for your job)...
>and I write to ask you for the recommended method to compile the sources
>(in Debian GNU/Linux platfom) in order to the arrow keys emit the history
>commands instead of... it seems that escape sequences...
>
>Python 3.5.0 (default, Sep 13 2015, 17:58:38)
>[GCC 4.9.2] on linux
>Type "help", "copyright", "credits" or "license" for more information.
 ^[[A^[[A^[[B^[[B
>
>(I run the configure, make, make test & make install scripts)

It seems your python is not installed with readline support, if
the arrow keys are not working.

You don't need to recompile python for this.
Instead you need to install this.
https://pypi.python.org/pypi/readline

But I am surprised that you need this, as my debian linux unstable
system has this out of the box, more or less always.

I think this is because I have this package installed
https://packages.debian.org/stretch/readline-common
(there are versions for testing and stable as well).

If I were you I would install this first and see if your
arrow problems go away.  If not, get out pip.

>Furthermore, I'd like also to ask a simple additional questions:
>
>Is yet an automatic indentation system implemented ?
>How to activate them ?

I am not sure what you mean by this.
If you, as I, was unhappy as anything about tab in the
interactive console (at the far margin) meaning 'tab complete
every builtin on the planet' rather than 'I'd like another level
of indent please' -- then, 3.5, you are good to go. :)  tabs typed
flush to the margin just indent.  tabs complete if you type them
in the middle of an identifier.

If you mean something else, then, well, explain it a little more, ok?


>Glus

Laura

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Re: convert element in a list to float

[Laura Creighton]

In a message of Sun, 13 Sep 2015 12:55:13 -0700, forums...@hotmail.com writes:
>
>
>For starters, I googled and saw a plethora of writings on how to convert an 
>entire list from string to float.   My interest is on select elements in the 
>list.  The output from the print statement: print scenarioList 
>  
>is as follows
>
>[ '300', '"N"', '1140', '"E"' ]
>
>I need to convert the first and third element to float.  
>  lat = ( float ) scenarioList [ 0 ]
>  lon = ( float ) scenarioList [ 2 ]
>
>fails (invalid syntax).  How can I achieve my objective. 
>
>Thanks in advance

Does this help?

>>> l = [ '300', '"N"', '1140', '"E"' ]
>>> [float(l[0]), l[1], float(l[2]), l[3]]
[300.0, '"N"', 1140.0, '"E"']

Laura

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Re: Phone Tree

[Laura Creighton]

Somewhere in there you may find that dictionary dispatching is
something worth doing.  I don't know.  This whole sort of problem
is sort of grating, in that it is trying to replicate one of the
most irritating user experiences on the planet ...

>From python3: Patterns, Recipes and Idioms

http://www.google.se/url?sa=t=j==s=web=5=0CEUQFjAEahUKEwiJv4CtxPTHAhVqvnIKHY68Bec=http%3A%2F%2Fpython-3-patterns-idioms-test.readthedocs.org%2Fen%2Flatest%2FMultipleDispatching.html=AFQjCNG0UFOKpxJNVDSCt9dtAJ55SC_zEA

The guts of the thing is a simple dictionary:

outcome = {
 (Paper, Rock): Outcome.WIN,
 (Paper, Scissors): Outcome.LOSE,
 (Paper, Paper): Outcome.DRAW,
 (Scissors, Paper): Outcome.WIN,
 (Scissors, Rock): Outcome.LOSE,
 (Scissors, Scissors): Outcome.DRAW,
 (Rock, Scissors): Outcome.WIN,
 (Rock, Paper): Outcome.LOSE,
 (Rock, Rock): Outcome.DRAW,
  }

Which, in this case, plays the child's game rock, paper, scissors with
2 players.  But you could use a tuple with 10 values.

If a lot of your outcomes are going to arrive at the same answer 'Stick
the device in a box, print off this shipping label, and send it via
UPS to our repair service centre.' then this approach will have more
appeal.

Sometimes what you want is to dispatch on a set of functions with
arguments, and you can stick that in your dictionary as well.

outcomes = { (a,c,d) : (function1_name, (arg1, arg2, arg3))
 (a, b, d) : (function2_name, (arg1,))}

But whether this is going to help or not really depends on your data.
If you find yourself itching for a case statement, then it probably
will.  But I am not sure that this was your intent in the first place.

Laura
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Re: Terminology: "reference" versus "pointer"

[Chris Angelico]

On Mon, Sep 14, 2015 at 4:04 AM, Akira Li <4kir4...@gmail.com> wrote:
>> (If I were drawing a picture rather than ASCII I'd add something to make
>> it clear that the pairs shown are list objects Like, it's a circle with
>> the word "list" and two pointer-boxes inside it.)
>
> "correct and complete" is impossible in the general case for any model.
>
> Imagine what happens if numpy arrays are used instead of Python lists:
>
>   lst = [numpy.array([1, 2]) for _ in range(3)]
>   a = [lst[0], lst[0]]
>   b = [lst[1], lst[2]]
>
> Note: there could be no a[0][0], a[0][1], etc corresponding Python
> objects until you explicitly reference them in the code. If there are no
> Python objects then you can't draw any arrows and therefore "box and
> arrows" model is incomplete.
>
> Or consider this collections of all Unicode characters:
>
>   class U:
>  def __len__(self):
>  return sys.maxunicode + 1
>  def __getitem__(self, index):
>  if index < 0:
>  index += len(self)
>  if 0 <= index < len(self):
>  return chr(index)
>  raise IndexError(index)
>
>   u = U()
>   print(u[0x61]) # -> a
>
> In this example, it is even more clear that the corresponding items
> might not exist until they are explicitly referenced in a program.

What you've shown there is that it's perfectly possible to have an
abstract collection which generates objects as they're needed. In the
same way, you could define an infinite range object, which effectively
has all positive odd numbers in it:

class Odd:
def __getitem__(self, index):
if index >= 0: return index * 2 + 1
raise IndexError(index)

Obviously it can't have objects representing every positive odd
number, because that's an infinite set. If you want to think of this
as containing all of those integers, sure, but now we're getting into
functional programming styles and ways of representing infinity in
finite RAM, and some things will look a bit different.

However, none of this has anything to do with Python's object model.
The expression "index * 2 + 1" results in the creation of new integer
objects as required, rather than simply retrieving them from some
containment list. The boxes-and-arrows stuff is all about pre-existing
objects; if I construct one list from another, I expect all the
references to be the same, but if I construct two Odd() objects, they
don't have to be:

>>> o1 = Odd(); x1 = o1[12345]
>>> o2 = Odd(); x2 = o2[12345]
>>> x1 is x2
False

Even though every Odd() must, by definition, contain the exact same
integers, it doesn't contain the same objects - it doesn't contain any
objects.

ChrisA
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Re: Terminology: "reference" versus "pointer"

[Random832]

Akira Li <4kir4...@gmail.com> writes:
> I'm not sure what "parcel tags" model is but if you mean these
> pictures[1] than it works in this case as well as any other (take *a*,
> *b* nametags, put them on the corresponding balloons that represents
> list objects).
>
> The only names left are *a* and *b* that refer to the corresponding
> lists. There is no ambiguity there to put *a*, *b* nametags.

But how do you make an a[0][0]/a[1][0] nametag to put on the "1" object?

> Lists as any other containers contain references to other objects and
> therefore "box and arrows" model provides _more details_ here[2,3]

Right, but why not use the *same* model to represent *namespaces*?

It seems like the "tags" model only exists to make the incorrect claim
that python doesn't have variables (the boxes are variables).

>> If the "parcel tags" model can't show it, then the "parcel tag" model
>> clearly is not a correct and complete depiction of how Python actually
>> works.
>> (If I were drawing a picture rather than ASCII I'd add something to make
>> it clear that the pairs shown are list objects Like, it's a circle with
>> the word "list" and two pointer-boxes inside it.)
>
> "correct and complete" is impossible in the general case for any
> model.

Everything you wrote here has the same issue: The "objects" you are
talking about do not physically exist, but are simply the result of
calling a method on the object. Therefore they do not *belong* on the
diagram, and the diagram not showing them does not mean the diagram is
not complete.

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Re: convert element in a list to float

[Mark Lawrence]

On 13/09/2015 20:55, forums...@hotmail.com wrote:


For starters, I googled and saw a plethora of writings on how to convert an 
entire list from string to float.   My interest is on select elements in the 
list.  The output from the print statement: print scenarioList

is as follows

[ '300', '"N"', '1140', '"E"' ]

I need to convert the first and third element to float.
   lat = ( float ) scenarioList [ 0 ]
   lon = ( float ) scenarioList [ 2 ]

fails (invalid syntax).  How can I achieve my objective.

Thanks in advance



Strong hint, you do not cast the strings to floats, you call the builtin 
float() function to do the conversion.


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what you can do for our language.

Mark Lawrence

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[issue25088] scipy (0.16.0) install fails on 3.5

[Carol Willing]

Carol Willing added the comment:

I am unable to pip install scipy, numpy, or pandas using 3.5.0 on OS X 10.10.4.

After installing Python 3.5 using the installer downloaded from Python.org 
page, I created a virtualenv using `pyvenv myscipy` and activated with `source 
myscipy\bin\activate`. `python -V` returns 3.5.0.

`pip install scipy` succeeds in `Collecting scipy` and downloading 100% of 
file. It hangs after that indication for 1m 21s with no warnings or errors. 
Cancelled the operation. I tried with scipy, numpy, pandas with no success. I 
also tried `python -m pip install scipy==0.16` and it also stalled with no 
warning or errors.

`pip search` and `pip install flask` worked fine in the 3.5 virtualenv.

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priority: normal -> high
stage:  -> needs patch

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[issue25063] shutil.copyfileobj should internally use os.sendfile when possible

[desbma]

desbma added the comment:

If I understand you correctly, a naive implementation like this:

use_chunk_copy = False
try:
  fdsrc = fsrc.fileno()
  fddst = fdst.fileno()
except OSError:
  # fallback on current chunk based Python copy
  use_chunk_copy = True
else:
  # we have 2 fd, try sendfile
  try:
os.sendfile(fdsrc, fddst)
  except AttributeError:
# sendfile not available
use_chunk_copy = True
if use_chunk_copy:
  # use current Python based chunk copy

...would not work because some file like objects expose fileno(), even though 
it does not accurately represent the file because they wrap it to add special 
behavior (like GzipFile).

I don't understand, if they alter the file behavior, why do they expose 
fileno()?

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[issue25087] Type variable substitution in type instances

[Guido van Rossum]

Guido van Rossum added the comment:

Good question. Let's discuss this in the type hinting / pep 484 tracker:

https://github.com/ambv/typehinting/issues/156

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Random832]

Laura Creighton  writes:
> But I am not sure how it is that a poor soul who just wants to print a
> railway schedule 'in local time' is supposed to know that Creighton is
> using Winnipeg time.

The same way they know that any other location is using whatever time it
uses. By the user having specified it (if the user's local time is wrong
they'll "obviously" know it as soon as the daylight saving transition is
supposed to happen but doesn't) or by checking the location against the
data at http://efele.net/maps/tz/canada/

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How to set the history commands visible ?

[Glus Xof]

Hi guys,

Today, a new python stable version was released (thanks for your job)...
and I write to ask you for the recommended method to compile the sources
(in Debian GNU/Linux platfom) in order to the arrow keys emit the history
commands instead of... it seems that escape sequences...

Python 3.5.0 (default, Sep 13 2015, 17:58:38)
[GCC 4.9.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> ^[[A^[[A^[[B^[[B

(I run the configure, make, make test & make install scripts)

Furthermore, I'd like also to ask a simple additional questions:

Is yet an automatic indentation system implemented ?
How to activate them ?

Glus
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Cannot create a virtualenv

[paul . hermeneutic]

Installing Py 3.5 and `pip install virtualenv` worked fine. However, I
cannot create a virtualenv.


"OSError: Command C:\ve\ve33\Scripts\python.exe -c "import sys, pip;
sys...d\"] + sys.argv[1:]))" setuptools pip wheel failed with error
code 1"

Any suggestions?
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[issue25088] scipy (0.16.0) install fails on 3.5

[Ned Deily]

Ned Deily added the comment:

For 3.4 and 2.7, the SciPy and matplotlib projects supply pre-compiled wheels 
for their distributions.  As of this moment, they haven't yet updated their 
PyPI entries with 3.5 wheels (.whl files).  Until they do, pip would fall back 
to trying to build them from source, which as Carol points out, will likely 
require installing additional non-Apple build tools, like gfortran.  Suggest 
you check on the mailing lists or other support forums for the SciPy and 
matplotlib projects to see when each expects to have OS X wheels available for 
3.5. I'd guess it won't be long since both are popular downloads.

--
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resolution:  -> third party
stage: test needed -> resolved
status: open -> closed
type: compile error -> 

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Re: Terminology: "reference" versus "pointer"

[Ben Finney]

Chris Angelico  writes:

> I think Ben's referring to taunting jmf, whom Mark called the "RUE" or
> "Resident Unicode Expert". There has been a long-standing antagonism
> between those two (which is completely understandable), and one which
> often spills over into vitriolic posts (which is less acceptable).

Chris has it right.

What's especially unacceptable is invoking that person for amusement,
irrelevant to the conversation. It's one thing to respond when a person
comes into a thread to troll unbidden; it is quite another to taunt them
unprompted.

-- 
 \ “I call him Governor Bush because that's the only political |
  `\  office he's ever held legally.” —George Carlin, 2008 |
_o__)  |
Ben Finney

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[issue25061] Add native enum support for argparse

[desbma]

desbma added the comment:

I would like the enum type to be stored directly.

With your approach, the user does not know what are the possible choices, until 
he/she tries a invalid value and get the exception. If I pass the enum type to 
the choice parameter, the help message is not very user friendly 
(""...) and does not accurately represent possible 
input strings.

Anyway, my first example snippet works and does what I need, but it feels a bit 
like a hack.
In my opinion this is a classic use case for enums, that should be handled more 
naturally by the argparse module.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Tim Peters]

[Tim]
>> Hi, Laura!  By "zoneinfo" here, we mean the IANA (aka "Olson") time
>> zone database, which is ubiquitous on (at least) Linux:
>>
>>https://www.iana.org/time-zones
>>
>>So "will a wrapping of zoneinfo handle XYZ?" isn't so much a question
>>about the wrapping as about what's in the IANA database.

[Laura]
> Then we had better be able to override it when it is wrong.

Anyone can write their own tzinfo implementing any rules they like,
and nobody is required to use anyone else's tzinfos.

That said, zoneinfo is the most extensive collection of time zone info
there is, so most people will probably use only that.

And that said, zoneinfo is inordinately concerned with recording
highly dubious guesses about what "the rules" were even over a century
ago.  Most people would probably be happy with a tzinfo that _only_
knew what "today's rules" are.  POSIX TZ rules give a simple way to
spell exactly that.  Simple, but annoyingly cryptic.  Gustavo's
`dateutil` already supplies a way to magically build a tzinfo
implementing a zone specified by a POSIX TZ rule string.  More obvious
ways to spell that are surely possible (like, for example, the obvious
ways).

Patches welcome ;-)


>> Best guess is that Creighton's rules are covered by that database's
>> America/Winnipeg entries.
>>
>> # Saskatchewan
>> # Other western towns (e.g. Lloydminster) are like Edmonton.
>> # Matthews and Vincent (1998) write that Denare Beach and Creighton
>> # are like Winnipeg, in violation of Saskatchewan law.

> I think that this will work.
> Creighton is just across the border from Flin Flan, Manitoba.  Indeed I think
> the problem of 'drunken people from Manitoba trying to get one hours more
> drinking done and being a menace on the highway' may have fueled the
> 'we are going to have DST in violation of the law' movement in Creighton.

:-)


> But I am not sure how it is that a poor soul who just wants to print a
> railway schedule 'in local time' is supposed to know that Creighton is
> using Winnipeg time.

I'm not sure how that poor soul would get a railway schedule
manipulable in Python to begin with ;-)

If it's "a problem" for "enough" users of a computer system, a Linux
admin could simply make "America/Creighton" a link to the
"America/Winnipeg" tzfile.  But doing that for every nameable place on
Earth might be considered annoying.

To cover everyone, you may even need to specify a street address
within "a city":

http://www.quora.com/Are-there-any-major-cities-divided-by-two-time-zones

Blame politicians for this.  I can assure you Guido is not responsible
for creating this mess ;-)
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[issue25082] Editing What's New In Python 3.5

[Yury Selivanov]

Yury Selivanov added the comment:

Thanks, Serhiy!

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Tim Peters]

[Laura]
>>> But I am not sure how it is that a poor soul who just wants to print a
>>> railway schedule 'in local time' is supposed to know that Creighton is
>>> using Winnipeg time.

[Tim]
>> I'm not sure how that poor soul would get a railway schedule
>> manipulable in Python to begin with ;-)

[Laura]
> Via Rail will give you a schedule when you book your tickets.  But I
> am wrong, it gives it to you in local time, which you can scrape or
> even use the via rail api.  So it is the person getting off in
> Creighton who wants to tell his relatives back in Halifax what
> time he is arriving (in their time) (so they can call him and
> avoid the hellish hotel surtax on long distance calls) who will
> have the problem.

Whatever time zone the traveler's railroad schedule uses, so long as
it sticks to just one the traveler subtracts the departure time from
the arrival time to determine how long the trip takes.  They add that
to the Halifax time at which they depart, and tell their Halifax
relatives the result.  They don't need to know anything about the
destination's time zone to do this, unless a daylight transition
occurs between departure and arrival, and the schedule itself
remembered to account for it.  In which case, pragmatically, they can
just add an hour "to be safe" ;-)


> And this is the sort of use case I think we will see a lot of.

But there's nothing new here:  datetime has been around for a dozen
years already, and nobody is proposing to add any new basic
functionality to tzinfos.  PEP 495 is only about adding a flag to
allow correct conversion of ambiguous local times (typically at the
end of DST, when the local clock repeats a span of times) to UTC.  So
if this were a popular use case, I expect we would already have heard
of it.  Note that Python zoneinfo wrappings are already available via,
at least, the pytz and dateutil packages.
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[issue25063] shutil.copyfileobj should internally use os.sendfile when possible

[STINNER Victor]

Changes by STINNER Victor :


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[issue25088] scipy (0.16.0) install fails on 3.5

[Naveen Togar]

Naveen Togar added the comment:

I didn't have any issues with either numpy or pandas.  I just tried installing 
matplotlib and that failed too.

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[issue25088] scipy (0.16.0) install fails on 3.5

[Carol Willing]

Carol Willing added the comment:

Naveen, I was able to resolve this problem for installation by installing 
gfortran using the instructions here: http://hpc.sourceforge.net/


After gfortran is successfully installed, I was able to ``pip install scipy 
-v`` the libraries that depend on gfortran. It did take 8m 39s to execute the 
install of scipy which is why I used the -v (verbose) option so that I could 
see that it was still working.

It would be good for numpy and scipy to indicate more clearly the absence or 
inability to find gfortran with a more obvious error message.

My recommendation is to close this issue if you are able to successfully 
install.

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[issue25063] shutil.copyfileobj should internally use os.sendfile when possible

[Martin Panter]

Martin Panter added the comment:

I don’t know the exact reasoning, but fileno() could be useful for other 
purposes, e.g. passing to stat() to find the last modification time, passing to 
select() to see if data is available.

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Guido van Rossum]

On Sun, Sep 13, 2015 at 5:24 AM, Laura Creighton  wrote:

> My question, is whether it will handle Creighton, Saskatchewan, Canada?
> Creighton is an odd little place.  Like all of Saskatchewan, it is
> in the Central time zone, even though you would expect it to be
> in the Mountain time zone based on its location on the globe.
> The people of Saskatchewan have decided not to adopt Daylight
> Savings time.  Except for the people of Creighton (and
> nearby Denare Beach) -- who _do_ observe Daylight savings time.
>
> makes for an interesting corner case, one that I remember for
> personal (and not economic, or professional) reasons.
>

Hi Laura!

Wouldn't it be sufficient for people in Creighton to set their timezone to
US/Central? IIUC the Canadian DST rules are the same as the US ones. Now,
the question may remain how do people know what to set their timezone to.
But neither pytz nor datetime can help with that -- it is up to the
sysadmin.

-- 
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[issue25089] Can't run Python Launcher on Windows

[Mark Lawrence]

New submission from Mark Lawrence:

I first asked a few days ago, see this thread 
http://www.gossamer-threads.com/lists/python/python/1216917.  You can work 
around it by running "repair" but it takes an age to run for what, to me 
anyway, is a minor irritant.

--
components: Windows
messages: 250588
nosy: BreamoreBoy, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Can't run Python Launcher on Windows
type: behavior
versions: Python 3.5

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Re: Phone Tree

[Denis McMahon]

On Sun, 13 Sep 2015 07:39:23 -0700, Azureaus wrote:

> Does anyone have any ideas for a more elegant solution? My thoughts are
> that I could use a tree data structure and hence make traversing the
> tree recursive based on yes or no answers. I'm happy to put the time in
> to explain these more complex ideas, I'm just hoping those with more
> expertise than myself could either help verify the idea or suggest
> alternatives.

The trick is to separate the data and the processing.

Each question has a yes, no answer, so start with a dictionary of data 
tuples (you could use a list, but using a dictionary makes the 
relationship slightly easier to walk through):

questions = {
1: (q1, response if yes, response if no),
2: (q2, response if yes, response if no)  }

The responses can be either a number of another question, or a result 
text.

Then your algorithm is broadly:

x = 1:
while x is numeric:
ask questions[x][0]
if answer is "yes":
x = questions[x][1]
if answer is "no":
x = questions[x][2]
answer is x

You can use a list instead of a dictionary, just remember 0 indexing when 
you're working out which question leads to which next question.

This way also makes for an interesting talking point about separating 
data and code, especially given the multiple if statements issue.

-- 
Denis McMahon, denismfmcma...@gmail.com
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Re: Terminology: "reference" versus "pointer"

[Akira Li]

Chris Angelico  writes:

> On Mon, Sep 14, 2015 at 9:17 AM, Akira Li <4kir4...@gmail.com> wrote:
>> If you mean this quote from [1]:
>>
>>   Although we commonly refer to "variables" even in Python (because it's
>>   common terminology), we really mean "names" or "identifiers". In
>>   Python, "variables" are nametags for values, not labelled boxes.
>>
>> then *name* is the term that is defined in the Python language
>> reference. The word "variable" we can use in day-to-day programming
>> _unless_ we are discussing issues that are specific to _naming and
>> binding_.  In that case, we should use the _exact_
>> terminology. Otherwise there is nothing wrong with using "variables"
>> casually in Python.
>
> Since you're talking about precise terminology, I think it would be
> better to say "name binding", rather than "naming and binding". When
> you talk of naming something (or someone!), you generally mean that
> it's possible to go from the thing to the (canonical) name. With
> people, for instance, you can walk up to someone and say "Hi! What's
> your name?", but with Python objects, you fundamentally can't.

"Naming and binding" is the title from the Python language reference
https://docs.python.org/3/reference/executionmodel.html#naming-and-binding

Otherwise, I agree with you ("name" is better here).

>>> Everything you wrote here has the same issue: The "objects" you are
>>> talking about do not physically exist, but are simply the result of
>>> calling a method on the object. Therefore they do not *belong* on the
>>> diagram, and the diagram not showing them does not mean the diagram is
>>> not complete.
>>
>> "do not physically exist" does not make sense. Objects are *never*
>> destroyed explicitly in Python (you can only make them
>> *unreachable*). You can disable garbage collection completely and it is
>> still will be Python. Immutable objects can be considered immortal e.g.:
>>
>>  (1+1) -- question: does the object that represents int(2) exist before
>> the expression is evaluated?
>>
>> The correct answer: it does not matter: int(2) can be created on the
>> fly, a cached int(2) can be reused by a specific implementation --
>> Python doesn't care.
>>
>> I don't see why the model that can't describe range(1) in Python 3
>> pretends to be complete.
>
> "Physically" isn't really the right word for it, given that objects in
> Python code aren't physical and therefore don't *ever* "physically
> exist". My bad there.
>
> But the objects completely do not exist. Yes, with integers you can't
> tell... but what about here?
>
> dependencies = collections.defaultdict(list)
> for fn in files:
> for dep in gather_deps(fn):
> dependencies[dep].append(fn)
>
> Until the moment when dependencies[dep] is requested for some new
> value of dep, the list *does not exist*. It is constructed anew.
> Obviously the end result of this is a dict of lists, and since those
> lists aren't accessible from anywhere else, it makes fine sense to
> talk about those lists as being "contained within" the (default)dict;
> but they clearly didn't exist until they were poked at. They're
> Heisenburg's Lists, I guess...

lists are _mutable_ in Python.

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[issue6691] Support for nested classes and function for pyclbr

[Terry J. Reedy]

Changes by Terry J. Reedy :


--
type:  -> enhancement
versions: +Python 3.6 -Python 3.2

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[issue25089] Can't run Python Launcher on Windows

[Steve Dower]

Steve Dower added the comment:

Yeah, it's basically impossible to manage PATH automatically. You've probably 
installed 3.5 just for yourself while 3.4 is installed for all users. In this 
case, 3.5 will always lose because Windows puts user paths after system paths.

You could modify 3.4 to remove it from PATH or use py.exe, which resolves 
versions correctly. Or you can modify your PATH manually.

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[issue24965] Implement PEP 498: Literal String Formatting

[Martin Panter]

Martin Panter added the comment:

Regarding the null terminator, I was mainly smoke testing your code. :) Maybe 
it would be too hard to support properly. Although I could imagine someone 
doing things like this:

>>> d = {b"key\x00": "value"}
>>> f"key={d[b'key\x00']}"  # Oops, escape code at wrong level
  File "", line 1
(d[b'key
   ^
SyntaxError: EOL while scanning string literal
>>> rf"key={d[b'key\x00']}"  # Corrected
'key=value'

I also finished quickly reading over the C code, with a couple more review 
comments. But I am not familiar with the files involved to thoroughly review.

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[issue25090] IDLE: remove noisy icons from class (module) browser

[Terry J. Reedy]

Terry J. Reedy added the comment:

Adding function arguments to the module browser, misnamed Class Browser, is 
#20827.  That leaves removing the noisy icons from class and def entries (where 
they do not fit anyway), as the concrete appearance change proposal here.  
Better to use the space for arguments.

Adding nested classes is #1612262 (9 years ago).  I just noticed that there is 
a 6 year old patch that needs to be reviewed.

The TextMate box has a checkmark at the current location. Having an editor know 
about an attached module browser and inform it of the cursor's location would 
be a separate issue. It would be relatively easy when code context is active.  
But nested classes and functions cannot be marked until they are displayed.

A module browser, even enhanced to display nested classes and functions, could 
not replace code context since the latter includes nested compound statements 
within functions.  I think code context would be even more useful if it were to 
display the complete context, using as many lines as needed, instead of some 
fixed number.  But I have not written a patch yet or opened an issue.

--
title: IDLE: alternative to class browser / code context -> IDLE: remove noisy 
icons from class (module) browser

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Re: [Datetime-SIG] Are there any "correct" implementations of tzinfo?

[Tim Peters]

[Tim]
>> Whatever time zone the traveler's railroad schedule uses, so long as
>> it sticks to just one

[Laura]
> This is what does not happen.  Which is why I have written a python
> app to perform conversions for my parents, in the past.

So how did they get the right time zone rules for Creighton?


>>But there's nothing new here:  datetime has been around for a dozen
>>years already, and nobody is proposing to add any new basic
>>functionality to tzinfos.  PEP 495 is only about adding a flag to
>>allow correct conversion of ambiguous local times (typically at the
>>end of DST, when the local clock repeats a span of times) to UTC.  So
>>if this were a popular use case, I expect we would already have heard
>>of it.  Note that Python zoneinfo wrappings are already available via,
>>at least, the pytz and dateutil packages.

> I am a happy user of pytz.  On the other hand, I think this means that
> my brain has gone through some sort of non-reversible transformation
> which makes me accurate, but not exactly sane on the issue.

pytz made some strange decisions, from the POV of datetime's intended
tzinfo design.  But it also solved a problem datetime left hanging:
how to disambiguate ambiguous local times.

The _intended_ way to model zones with UTC offset transitions was via
what the docs call a "hybrid" tzinfo:  a single object smart enough on
its own to figure out, e.g., whether a datetime's date and time are in
"daylight" or "standard" time.  However, there's currently no way for
such a tzinfo to know whether an ambiguous local time is intended to
be the earlier or the later of repeated times.  PEP 495 aims to plug
that hole.

pytz solves it by _never_ creating a hybrid tzinfo.  It only uses
eternally-fixed-offset tzinfos.  For example, for a conceptual zone
with two possible total UTC offsets (one for "daylight", one for
"standard"), there two distinct eternally-fixed-offset tzinfo objects
in pytz.  Then an ambiguous time is resolved by _which_ specific
tzinfo object is attached.  Typically the "daylight" tzinfo for the
first time a repeated local time appears, and the "standard" tzinfo
for its second appearance.

In return, you have to use .localize() and .normalize() at various
times, because pytz's tzinfo objects themselves are completely blind
to the possibility of the total UTC offset changing. .localize() and
.normalize() are needed to possibly _replace_ the tzinfo object in
use, depending on the then-current date and time.

OTOH, `dateutil` does create hybrid tzinfo objects.  No dances are
ever needed to possibly replace them.  But it's impossible for
dateutil's tzinfos to disambiguate times in a fold.  Incidentally,
dateutil also makes no attempt to account for transitions other than
DST (e.g., sometimes a zone may change its _base_ ("standard") offset
from UTC).

So, yup, if you're thoroughly indoctrinated in pytz behavior, you will
be accurate but appear insane to Guido ;-)  At a semantic level, a
pytz tzinfo doesn't capture the notion of a zone with offset changes -
it doesn't even try to.  All knowledge about offset changes is inside
the .localize() and .normalize() dances.


> I think I have misunderstood Alexander Belopolsky as saying that
> datetime had functionality which I don't think it has. Thus I thought
> we must be planning to add some functionality here.  Sorry about this.

Guido told Alex to stop saying that ;-)  You can already get
eternally-fixed-offset classes, like pytz does, on (at least) Linux
systems by setting os.environ['TZ'] and then exploiting that
.astimezone() without an argument magically synthesizes an
eternally-fixed-offset tzinfo for "the system zone" (which the TZ
envar specifies) current total UTC offset.  That's not really
comparable to what pytz does, except at a level that makes a lot of
sense in theory but not much at all in practice ;-)


> However, people do need to be aware, if they are not already, that
> people with 3 times in 3 different tz will want to sort them.  Telling
> them that they must convert them to UTC before they do so is, in my
> opinion, a very fine idea. Expecting them to work this out by themselves
> via a assertion that the comparison operator is not transitive, is,
> I think, asking a lot of them.

Of course.  Note that it's _not_ a problem in pytz, though:  there are
no sorting (or transitivity) problems if the only tzinfos you ever use
have eternally fixed UTC offsets.  There are no gaps or folds then,
and everything works in an utterly obvious way - except that you have
to keep _replacing_  tzinfos when they become inappropriate for the
current dates and times in the datetimes they're attached to.
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[issue25089] Can't run Python Launcher on Windows

[Steve Dower]

Steve Dower added the comment:

I don't understand what you did and what the result was from that thread.

* What options did you select when installing 3.5?
* What other Python versions did you have? What options were used to install 
them?
* Where was py.exe before installing 3.5?
* Can you attach all of the logs from your 3.5 install (from your %TEMP%)?

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Re: convert element in a list to float

[Steven D'Aprano]

Hi Forums_MP and welcome,


On Mon, 14 Sep 2015 05:55 am, forums...@hotmail.com wrote:

> For starters, I googled and saw a plethora of writings on how to convert
> an entire list from string to float.   My interest is on select elements
> in the list.  The output from the print statement: print scenarioList
>   
> is as follows
> 
> [ '300', '"N"', '1140', '"E"' ]
> 
> I need to convert the first and third element to float.
>   lat = ( float ) scenarioList [ 0 ]
>   lon = ( float ) scenarioList [ 2 ]
> 
> fails (invalid syntax).  How can I achieve my objective.


By now you have hopefully discovered that the answer is to call float as a
function:

lat = float(scenarioList[0])


but I wonder what in the documentation or examples you saw suggested to you
that Python used the C type-cast syntax `(float)value`? Whatever it was
that gave you this wrong impression needs to be fixed.




-- 
Steven

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[issue25089] Can't run Python Launcher on Windows

[Terry J. Reedy]

Terry J. Reedy added the comment:

For anyone else reading this, Mark says he already re-tried with 3.5.0.

The only problem I had with the install on my Win7, with 2.7.10, 3.4.3, and 
3.5.0rc3 already present, is that 3.4.3 is still the default python (started by 
'python') in spite of checking everything relevant when installing 3.5.0.

--
nosy: +terry.reedy

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Re: Terminology: "reference" versus "pointer"

[rurpy--- via Python-list]

On 09/13/2015 06:50 AM, Steven D'Aprano wrote:
> On Sun, 13 Sep 2015 04:45 am, ru...@yahoo.com wrote:
>> On 09/12/2015 10:32 AM, Steven D'Aprano wrote:
>>> On Sat, 12 Sep 2015 02:42 pm, Random832 wrote:
>>> [...]
>>> Computer science and IT is *dominated* by a single usage for "pointer" --
>>> it's an abstract memory address. The fundamental characteristics of
>>> pointers are:
>>
>> Just upthread, you claimed something was "universally agreed"
> 
> I did? "Universially agreed" doesn't sound like something I would say. Do
> you have a link to where I said that?
> I think you're confusing me with somebody else. Somebody who is not me.

I should have copy/pasted rather than paraphrasing from memory. You
said "near-universal agreement" ("Re: Python handles globals badly",
2015-09-10). The difference does not change my response at all.

> [...]
> I have little problem with you using "pointer" as a metaphor: "Python
> variables are like pointers in these ways...". I do have a problem with you
> insisting that they are pointers.

First, I am very cautious about about using absolute and dogmatic
words like *are* [pointers] (although I probably have occasionally
for brevity or in response to someones else's dogmatism.)

If you go back over what I've written, I think you'll see that my
main point is that describing what is in python "variables" and objects
as pointers can be useful in some circumstances as an alternative
to the current official description (with people who have had some
experience with pointers in other languages, for example).

The "standard definition" you keep referring to (and basing your
arguments on was):

  An address, from the point of view of a programming language.[...]

Wikipedia also seems to define pointer in terms of memory address.
As I said, I think when describing the behavior of a language in abstract
terms it is perfectly valid to take "address" equally abstractly (eg a
token that lets you retrieve the same data every time you use it) but
unfortunately for me Wikipedia defines "address" as the conventional
linear numbers used in real-world computers. And I am not going to
waste my time trying to convince anyone that Wikipedia is wrong or
the context in inappropriate.

Wikipedia also makes a distinction between "pointer" as something
that refers to some data by "memory address" and "reference" which
refers to some data by any means (including but not limited to a
memory address, eg offset from current address or url). That was
not distinction I knew of; I considered both terms as being more or
less synonymous (in the general sense, obviously they are different
in specific domains like C++).

So I will retract any claim I made about "pointer" being a technically
correct term (because Python-the-language imposes no restrictions on
on how references are implemented.)

Nevertheless I'll continue to maintain that it is useful to explain
how python works in terms of pointers in that:

1) The distinction between abstract pointers(*) and references
is non-existant or irrelevant in Python for any existing
implementation.

2) You can accurately specify python-the-language in term of
abstract pointers (ie, "as if") regardless of how it is currently
specified.

3) People who've used pointers in other languages are more easily
able to grasp Python semantics when presented in term of pointers,
a concept they already understand.

(*) by "abstract pointers" I mean pointers in the sense given in
your definition, not C datatype pointers. If you insist on "references"
that's ok too, the description can be accompanied with a wink and a
whispered, "hey, references are really like pointers".)

Those are my opinions, if you have any clear counter examples I
would certainly like to know of them but I've not seen or read
anything yet that indicates they are wrong.

Below I snipped out all your responses that were essentially "that's
not the standard definition of pointers", having addressed those above.

> [...]

>> It may not be appropriate way to describe Python for everybody but
>> it is perfectly reasonable (and even preferable) for people with
>> an understanding of "pointers" from some other language. And for
>> those people who don't then one could argue they are a clean slate
>> and using the word "pointer" won't hurt.
> 
> No, it is not reasonable. 
> 
> You want to insist that `x = 23` in Python code makes x a pointer. But that
> Python snippet is analogous to to the following C and Pascal snippets:
> 
> # C
> int x = 23;
> 
> [...pascal example snipped...]
> 
> Do you insist that they are pointers to? 
>
> Then everything is a pointer, and the word has no meaning.
>
> Regardless of which of the three languages we are talking about, the
> assignment `x = 23` does not mean "bind some value to x which, when
> dereferenced, gives the value 23".
>
> The value bound to x is 23, not some
> indirect pointer to 23.

Your problem is that the C snippet is not, as you claim, analogous
to the Python 

Re: Can't use Python Launcher on Windows after update to 3.5

[Mark Lawrence]

On 10/09/2015 16:56, Mark Lawrence wrote:

On 10/09/2015 11:20, Tim Golden wrote:

On 10/09/2015 00:52, Mark Lawrence wrote:

I've installed 3.5 for all users so it's in C:\Program Files

From
https://docs.python.org/3.5/using/windows.html#from-the-command-line it
says "System-wide installations of Python 3.3 and later will put the
launcher on your PATH. The launcher is compatible with all available
versions of Python, so it does not matter which version is installed. To
check that the launcher is available, execute the following command in
Command Prompt:", but:-

C:\Users\Mark\Documents\MyPython>py -3.4
'py' is not recognized as an internal or external command,
operable program or batch file.

Further running ftype shows nothing for Python, assoc just gives this
.pyproj=VisualStudio.Launcher.pyproj.14.0.  Surely this is wrong?

Before I go to the bug tracker to raise an issue could somebody please
confirm what I'm seeing, thanks.



Well I've just installed 64-bit 3.5.0rc4 via the web installer (ie this:
https://www.python.org/ftp/python/3.5.0/python-3.5.0rc4-amd64-webinstall.exe)

onto a machine with 64-bit 3.4.2 already installed. I went for the
default install.

It all seems to be ok and py -3.4 --version gives  me "Python 3.4.2" as
expected. assoc/ftype both look ok. c:\windows\py.exe has the versions &
dates I expect.

TJG



So I ran the 64-bit 3.5.0rc4 via the web installer and still no joy. Ran
repair with same and it's business as usual.  I'm not that bothered,
it's here for the record should anybody else come searching, so chalk it
up to experience and move on.  Thanks anyway :)



Exactly the same thing happened when I upgraded to 3.5.0. so raised 
http://bugs.python.org/issue25089 just in case it hurts other people 
more than it hurts me.


--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

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Re: Terminology: "reference" versus "pointer"

[Akira Li]

Random832  writes:

> Akira Li <4kir4...@gmail.com> writes:
>> I'm not sure what "parcel tags" model is but if you mean these
>> pictures[1] than it works in this case as well as any other (take *a*,
>> *b* nametags, put them on the corresponding balloons that represents
>> list objects).
>>
>> The only names left are *a* and *b* that refer to the corresponding
>> lists. There is no ambiguity there to put *a*, *b* nametags.
>
> But how do you make an a[0][0]/a[1][0] nametag to put on the "1" object?

a[0][0]/a[1][0] are not names. Though if we want to talk about the
corresponding objects then a[0][0]/a[1][0] could be used instead of
names (as a way to identify them). 

>> Lists as any other containers contain references to other objects and
>> therefore "box and arrows" model provides _more details_ here[2,3]
>
> Right, but why not use the *same* model to represent *namespaces*?

If it works for your case; use it. The links [2,3] show that It does
work in this case (if it is correct to call what they show "box and
arrows" model).

> It seems like the "tags" model only exists to make the incorrect claim
> that python doesn't have variables (the boxes are variables).

If you mean this quote from [1]:

  Although we commonly refer to "variables" even in Python (because it's
  common terminology), we really mean "names" or "identifiers". In
  Python, "variables" are nametags for values, not labelled boxes.

then *name* is the term that is defined in the Python language
reference. The word "variable" we can use in day-to-day programming
_unless_ we are discussing issues that are specific to _naming and
binding_.  In that case, we should use the _exact_
terminology. Otherwise there is nothing wrong with using "variables"
casually in Python.

Notice: that [2,3] model is different from "labelled boxes" model. There
are arrows from *a*/*b* _to_ list objects i.e., *a*/*b* are not boxes
that _contain_ list objects within --
_otherwise you have to put the *same* list into two *different* boxes_ --
let's not investigate quantum paradoxes here. The only difference from
"parcel tags" model is that list items do not have explicit names.

>>> If the "parcel tags" model can't show it, then the "parcel tag" model
>>> clearly is not a correct and complete depiction of how Python actually
>>> works.
>>> (If I were drawing a picture rather than ASCII I'd add something to make
>>> it clear that the pairs shown are list objects Like, it's a circle with
>>> the word "list" and two pointer-boxes inside it.)
>>
>> "correct and complete" is impossible in the general case for any
>> model.
>
> Everything you wrote here has the same issue: The "objects" you are
> talking about do not physically exist, but are simply the result of
> calling a method on the object. Therefore they do not *belong* on the
> diagram, and the diagram not showing them does not mean the diagram is
> not complete.

"do not physically exist" does not make sense. Objects are *never*
destroyed explicitly in Python (you can only make them
*unreachable*). You can disable garbage collection completely and it is
still will be Python. Immutable objects can be considered immortal e.g.:

 (1+1) -- question: does the object that represents int(2) exist before
the expression is evaluated?

The correct answer: it does not matter: int(2) can be created on the
fly, a cached int(2) can be reused by a specific implementation --
Python doesn't care.

I don't see why the model that can't describe range(1) in Python 3
pretends to be complete.

[1]
http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#python-has-names
[2]
http://www.pythontutor.com/visualize.html#code=a0+%3D+a1+%3D+%5B1,+2%5D%0Ab0+%3D+%5B1,+2%5D%0Ab1+%3D+%5B1,+2%5D%0Aa+%3D+%5Ba0,+a1%5D%0Ab+%3D+%5Bb0,+b1%5D%0Adel+a0,+a1,+b0,+b1%0A=display=opt-frontend.js=false=false=false=3=%5B%5D=6
[3]
http://www.pythontutor.com/visualize.html#code=a0+%3D+a1+%3D+%5B1,+2%5D%0Ab0+%3D+%5B1,+2%5D%0Ab1+%3D+%5B1,+2%5D%0Aa+%3D+%5Ba0,+a1%5D%0Ab+%3D+%5Bb0,+b1%5D%0Adel+a0,+a1,+b0,+b1%0Aa%5B0%5D%5B0%5D+%3D+%22Oops!%22=display=opt-frontend.js=false=false=false=3=%5B%5D=7



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[issue25090] IDLE: alternative to class browser / code context

[Mark Roseman]

New submission from Mark Roseman:

Proposal for an alternative or perhaps replacement of both the code context 
extension, as well as the class browser (rooted at a particular file, not the 
path browser).

I'll direct your attention to the attached browser.png. On the right is IDLE's 
class browser window of ClassBrowser.py. On the left, I've got the same file 
loaded into TextMate. 

In the TextMate status bar, it shows you where you're currently located (here, 
in the __init__ function). When you click on that part of the status bar, it 
brings up a scrollable menu showing the structure of the file. I think it's 
easier to read than IDLE's, despite having more information (description of the 
parameters), thanks to reduction in 'chart junk'.

Downside of this approach is that you can't have a window along the side so you 
can navigate the code while seeing the class display. Though that might best be 
achieved if IDLE added a sidebar, rather than a true separate window.

--
components: IDLE
files: browser.png
messages: 250589
nosy: kbk, markroseman, roger.serwy, terry.reedy
priority: normal
severity: normal
status: open
title: IDLE: alternative to class browser / code context
type: enhancement
versions: Python 2.7, Python 3.5, Python 3.6
Added file: http://bugs.python.org/file40452/browser.png

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Re: convert element in a list to float

[Denis McMahon]

On Sun, 13 Sep 2015 23:02:55 +0200, Laura Creighton wrote:

> In a message of Sun, 13 Sep 2015 12:55:13 -0700, forums...@hotmail.com
> writes:
>>
>>For starters, I googled and saw a plethora of writings on how to convert
>>an entire list from string to float.   My interest is on select elements
>>in the list.  The output from the print statement: print scenarioList
>>  
>>is as follows
>>
>>[ '300', '"N"', '1140', '"E"' ]
>>
>>I need to convert the first and third element to float.
>>  lat = ( float ) scenarioList [ 0 ]
>>  lon = ( float ) scenarioList [ 2 ]
>>
>>fails (invalid syntax).  How can I achieve my objective.
>>
>>Thanks in advance
> 
> Does this help?
> 
 l = [ '300', '"N"', '1140', '"E"' ]
 [float(l[0]), l[1], float(l[2]), l[3]]
> [300.0, '"N"', 1140.0, '"E"']

Here's a method that will convert any value in a list that can be made a 
float into a float, and (I think) should leave all others as they are. It 
users a helper function and a list comprehension.

>>> def tofloat(x):
... try:
... return float(x)
... except ValueError:
... return None
... 
>>> l = [ '300', '"N"', '1140', '"E"' ]
>>> l = [ tofloat(x) or x for x in l ]
>>> l
[300.0, '"N"', 1140.0, '"E"']

-- 
Denis McMahon, denismfmcma...@gmail.com
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