Problem with StreamReaderWriter on 3.6.3?
I came across this code in Google cpplint.py, a Python script for
linting C++ code. I was getting funny results with Python 3.6.3, but it
worked fine under 2.7.13
I've tracked the problem to an issue with StreamReaderWriter; the
traceback and error never shows under 3. The _cause_ of the error is
clear (xrange not in Py3), but I need the raised exception to show.
I'm running Python 3.6.3 32bit on Windows 10. I also get the same
results on Python 3.5.2 on Ubuntu (under WSL)
I'm not super familiar with rebinding stderr with codecs, but I'm
guessing they are doing it because of some Unicode issue they may have
been having.
I have a workaround - drop the rebinding - but it seems like there might
be an error in StreamReaderWriter.
Do other people see the same behaviour?
Is there something I'm not seeing or understanding?
Would I raise it on issue tracker?
Peter
--
import sys
import codecs
sys.stderr = codecs.StreamReaderWriter(
sys.stderr, codecs.getreader('utf8'), codecs.getwriter('utf8'),
'replace')
# This should work fine in Py 2, but raise an exception in Py3
# But instead Py3 "swallows" the exception and it is never seen
print(xrange(1, 10))
# Although this line doesn't show in Py 3 (as the script has silently
crashed)
print("This line doesn't show in Py 3")
--
--
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Re: Re: Problem with StreamReaderWriter on 3.6.3? SOLVED
Thanks MRAB, your solution works a treat.
I'm replying to the list so others can know that this solution works.
Note that sys.stderr.detach() is only available in >= 3.1, so one might
need to do some version checking to get it to work properly in both
versions. It also can mess up with the buffering and therefore the order
of the output of stderr vs stdout.
Thanks again.
Peter
On 20/10/2017 10:19 AM, MRAB wrote:
On 2017-10-19 22:46, Peter via Python-list wrote:
I came across this code in Google cpplint.py, a Python script for
linting C++ code. I was getting funny results with Python 3.6.3, but it
worked fine under 2.7.13
I've tracked the problem to an issue with StreamReaderWriter; the
traceback and error never shows under 3. The _cause_ of the error is
clear (xrange not in Py3), but I need the raised exception to show.
I'm running Python 3.6.3 32bit on Windows 10. I also get the same
results on Python 3.5.2 on Ubuntu (under WSL)
I'm not super familiar with rebinding stderr with codecs, but I'm
guessing they are doing it because of some Unicode issue they may have
been having.
I have a workaround - drop the rebinding - but it seems like there might
be an error in StreamReaderWriter.
Do other people see the same behaviour?
Is there something I'm not seeing or understanding?
Would I raise it on issue tracker?
Peter
--
import sys
import codecs
sys.stderr = codecs.StreamReaderWriter(
sys.stderr, codecs.getreader('utf8'), codecs.getwriter('utf8'),
'replace')
# This should work fine in Py 2, but raise an exception in Py3
# But instead Py3 "swallows" the exception and it is never seen
print(xrange(1, 10))
# Although this line doesn't show in Py 3 (as the script has silently
crashed)
print("This line doesn't show in Py 3")
--
StreamReaderWriter is being passed an encoder which returns bytes
(UTF-8), but the output stream that is being passed, to which it will
be writing those butes, i.e. the original sys.stderr, expects str.
I'd get the underlying byte stream of stderr using .detach():
sys.stderr = codecs.StreamReaderWriter(sys.stderr.detach(),
codecs.getreader('utf8'), codecs.getwriter('utf8'), 'replace')
--
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Unexpected behaviour with DeprecationWarning, Python 3.7 and escape codes
I understand that Python 3.7 now issues DeprecationWarning for code
entered in the interactive shell and also for single-module programs. I
see this behaviour with:
C:\wrk> python
python 3.7.0 (v3.7.0:...
import imp
__main__:1: DeprecationWarning: the imp module is deprecated...
But if I use an unknown escape code, then the expected warning doesn't
issue:
print('Hello \world')
Hello \world
But if I explicitly turn on default warnings, then I do get it:
C:\wrk> python -Wd
print('Hello \world')
:1: DeprecationWarning: invalid escape sequence \w
Hello \world
Shouldn't I see the "invalid escape sequence" deprecation warning under
3.7 without having to turn on default warnings? They are both warnings
of class DeprecationWarning. Am I not seeing something? Is this a bug?
I suspect it might have something to do with /when/ the warning is
evaluated (parsing time vs runtime), but I'm not sure, and I'm not sure
if that should be relevant to whether the warning is in fact raised. (I
am aware of PEP 565)
Running CPython 3.7.0 on Windows 10, standard
Thanks for your insights.
Peter
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Re: Re: CURSES WINDOWS
I get this: C:\Users\Me> py Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 16:07:46) [MSC v.1900 32 bit (Inte l)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> import curses Traceback (most recent call last): File "", line 1, in File "C:\Program Files (x86)\Python36-32\lib\curses\__init__.py", line 13, in from _curses import * ModuleNotFoundError: No module named '_curses' >>> I get the same on py 2.7 On 5/09/2018 4:59 PM, Anssi Saari wrote: shinobi@f153.n1.z21.fsxnet (shinobi) writes: Hello All, can anyone please let me know what's the path to port linux python curses program to Windows? Is there really anything that needs to be done? At least a simple hello world python curses program runs on Windows and Linux with no changes. -- https://mail.python.org/mailman/listinfo/python-list
Re: Debug script under pdb, how to avoid a bunch of errors caused by the exit()?
I'm on 3.7.0 on Win 10, and get a different result. No traceback.
Perhaps it's a bug in 3.4 that was fixed subsequently.
C:\test> py -m pdb bugInPDB.py
> c:\test\buginpdb.py(1)()
-> password = 'bad'
(Pdb) tbreak 3
Breakpoint 1 at c:\test\buginpdb.py:3
(Pdb) cont
Deleted breakpoint 1 at c:\test\buginpdb.py:3
> c:\test\buginpdb.py(3)()
-> print('bad password')
(Pdb) cont
bad password
The program exited via sys.exit(). Exit status: None
> c:\test\buginpdb.py(1)()
-> password = 'bad'
(Pdb) q
C:\test>
On 6/09/2018 7:38 PM, Jach Fong wrote:
Here the script file, test0.py:
--
password = 'bad'
if password == 'bad':
print('bad password')
exit()
else:
print('good password')
print('something else to do')
When running it under Python3.4 Windows Vista, no problem at all.
D:\Works\Python>py test0.py
bad password
But if debug it under pdb:
D:\Works\Python>py -m pdb test0.py
> d:\works\python\test0.py(1)()
-> password = 'bad'
(Pdb) tbreak 3
Breakpoint 1 at d:\works\python\test0.py:3
(Pdb) cont
Deleted breakpoint 1 at d:\works\python\test0.py:3
> d:\works\python\test0.py(3)()
-> print('bad password')
(Pdb) cont
bad password
The program exited via sys.exit(). Exit status: None
> d:\works\python\test0.py(1)()
-> password = 'bad'
(Pdb) Traceback (most recent call last):
File "C:\Python34\lib\pdb.py", line 1661, in main
pdb._runscript(mainpyfile)
File "C:\Python34\lib\pdb.py", line 1542, in _runscript
self.run(statement)
File "C:\Python34\lib\bdb.py", line 431, in run
exec(cmd, globals, locals)
File "", line 1, in
File "d:\works\python\test0.py", line 1, in
password = 'bad'
File "d:\works\python\test0.py", line 1, in
password = 'bad'
File "C:\Python34\lib\bdb.py", line 48, in trace_dispatch
return self.dispatch_line(frame)
File "C:\Python34\lib\bdb.py", line 66, in dispatch_line
self.user_line(frame)
File "C:\Python34\lib\pdb.py", line 259, in user_line
self.interaction(frame, None)
File "C:\Python34\lib\pdb.py", line 346, in interaction
self._cmdloop()
File "C:\Python34\lib\pdb.py", line 319, in _cmdloop
self.cmdloop()
File "C:\Python34\lib\cmd.py", line 126, in cmdloop
line = input(self.prompt)
ValueError: I/O operation on closed file.
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> c:\python34\lib\cmd.py(126)cmdloop()
-> line = input(self.prompt)
(Pdb) Traceback (most recent call last):
File "C:\Python34\lib\pdb.py", line 1661, in main
pdb._runscript(mainpyfile)
File "C:\Python34\lib\pdb.py", line 1542, in _runscript
self.run(statement)
File "C:\Python34\lib\bdb.py", line 431, in run
exec(cmd, globals, locals)
File "", line 1, in
File "d:\works\python\test0.py", line 1, in
password = 'bad'
File "d:\works\python\test0.py", line 1, in
password = 'bad'
File "C:\Python34\lib\bdb.py", line 48, in trace_dispatch
return self.dispatch_line(frame)
File "C:\Python34\lib\bdb.py", line 66, in dispatch_line
self.user_line(frame)
File "C:\Python34\lib\pdb.py", line 259, in user_line
self.interaction(frame, None)
File "C:\Python34\lib\pdb.py", line 346, in interaction
self._cmdloop()
File "C:\Python34\lib\pdb.py", line 319, in _cmdloop
self.cmdloop()
File "C:\Python34\lib\cmd.py", line 126, in cmdloop
line = input(self.prompt)
ValueError: I/O operation on closed file.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\Python34\lib\runpy.py", line 170, in _run_module_as_main
"__main__", mod_spec)
File "C:\Python34\lib\runpy.py", line 85, in _run_code
exec(code, run_globals)
File "C:\Python34\lib\pdb.py", line 1688, in
pdb.main()
File "C:\Python34\lib\pdb.py", line 1680, in main
pdb.interaction(None, t)
File "C:\Python34\lib\pdb.py", line 346, in interaction
self._cmdloop()
File "C:\Python34\lib\pdb.py", line 319, in _cmdloop
self.cmdloop()
File "C:\Python34\lib\cmd.py", line 126, in cmdloop
line = input(self.prompt)
ValueError: I/O operation on closed file.
D:\Works\Python>
How to get rid of these?
Best Regards,
Jach Fong
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Re: Re: Python indentation (3 spaces)
It's also useful to be aware of the standard tabnanny module for "Detection of ambiguous indentation". Very useful for highlighting problems with tabs and spaces. Peter On 8/10/2018 2:32 AM, Terry Reedy wrote: On 10/5/2018 11:30 PM, Ryan Johnson wrote: The point that OP is trying to make is that a fixed standard that is distinguishable from the even-spacing Tab-length convention in code and text editors will establish a level of trust between the end developer and upstream developers or co-developers who may not have the same development environment. And my counter point is that a) we will not change the standard and b) we deliver an editor that by default enforces the standard, and c) to be fair, many other editors will do the same. For example, the first Python library I ever tried to use was What library? From where? poorly maintained and had spaces on one line with tabs on the next, and the author mixed naming conventions and syntax from Python 2 and 3 in his code. That type of experience doesn’t exactly instill trust in the coding language’s standards, when a noob tries to use a library they found and ends up having to debug weird errors with weirder error messages on the first project they do. I don't follow the logic. If someone violates a law, does that make the law bad? And if people follow a law, does that make it good? People obviously should not distribute buggy messes, at least not without warning. Were you using the library with an unsupported version? Or inform the author or distributor? Flexibility is great until the learning curve comes into play. That said, there is an easy fix for tab misuse: in Visual Studio Code, you can replace all Tabs with Spaces by highlighting the entire code block, hitting Tab once and Shift-Tab after. IDLE does that also. -- https://mail.python.org/mailman/listinfo/python-list
Re: Re: PEP 394
I'd imagine the PEP would stay as active, but changed so that: python2 -> always refers to python v2 python3 -> always refers to python v3 python -> which currently refers to python v2 will change to point to python v3 I don't know when the core team would be considering this. The PEP was last updated in April this year, so it's clearly still active. I would imagine this change would happen when python v2 ends updates at end of 2019, although I personally would like to see it happen earlier. Peter L On 20/10/2018 6:47 PM, Anders Wegge Keller wrote: På Sat, 20 Oct 2018 12:57:45 +1100 Ben Finney skrev: Anders Wegge Keller writes: Short and simple: Do you expect PEP 394 to change status The status of PEP 394 today is “Active”. What change of status would you expect in this Informational PEP? One possible change would be that it would become archived, ceased to be, bereft of life, resting in peace or maybe even retired. I don't have any particular status change I want to see; I merely ask what other experienced python developers expect to happen. -- https://mail.python.org/mailman/listinfo/python-list
Re: Accessing clipboard through software built on Python
On 28/10/2018 12:17 AM, Musatov wrote: I am wondering if Python could be used to write a program that allows: 1. Highlight some text 2. Ctl+HOTKEY1 stores the string of text somewhere as COPIEDTEXT1 3. Highlight another string of text 4. Ctl+HOTKEY1 stores another string of text somewhere as COPIEDTEXT2 THEN 5. Ctl+HOTKEY2 pastes COPIEDTEXT1 6. Ctl+HOTKEY2 pastes COPIEDTEXT2 I found "pyperclip" and "Tkinter" but I don't know where to start. Thanks, Musatov You might find the GUI automation tool Skiuli or the newer SikuliX programs useful. They can be used to script a GUI and perform operations. http://www.sikuli.org/ If you're on Windows then the COM interface can be useful (if the program you want to copy from supports it). Peter -- https://mail.python.org/mailman/listinfo/python-list
Re: AES Encryption/Decryption
On 3/11/2018 1:42 AM, Jeff M wrote: Python newbie here, looking for code samples for encrypting and decrypting functions, using AES. See lots of stuff on the interwebs, but lots of comments back an forth about bugs, or implemented incorrect, etc... I need to encrypt some strings that will be passed around in URL, and then also some PII data at rest. Thanks. Although not specifically what you asked about, it's also useful to be aware of the new secrets module in Python 3.6. Peter -- https://mail.python.org/mailman/listinfo/python-list
Re: Re: Generators, generator expressions, and loops
Lovely, succinct answers.
On 17/11/2018 2:44 AM, Ian Kelly wrote:
On Fri, Nov 16, 2018 at 7:57 AM Steve Keller wrote:
I have looked at generators, generator expressions, and iterators and
I try to get more familiar with these.
1. How would I loop over all (with no upper bound) integers or all
powers of two, for example?
In C it would be
for (int i = 0; ; i++) { ... } or for (int i = 1; ; i *= 2) { ... }
In Python, I could define a generator
def powers():
i = 1
while True:
yield(i)
i *= 2
for i in powers():
...
More elegant are generator expressions but I cannot think of a way
without giving an upper limit:
for i in (2 ** i for i in range(100)):
...
which looks ugly. Also, the double for-loop (and also the two loops
in the above exmaple, for + while in the generator) look unnatural,
somehow, i.e. loop over all elements which are created by a loop.
Is there a more beautyful way?
Some options:
from itertools import count
def powers():
for i in count():
yield 2 ** i
for i in (2 ** i for i in count()):
...
for i in map(lambda x: 2 ** x, count()):
...
from functools import partial
from operator import pow
for i in map(partial(pow, 2), count()):
...
Take your pick.
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Re: Unable to find newly installed Python 3.7.1
On 23/11/2018 10:51 PM, Edward Popko wrote: Snake people: I'm a Java person and thought to try Python for Windows. I installed Python 3.7.1 (64-bit) hoping for an IDE, documentation and even a sample or two. The python-3.7.1-amd64.exe unpacks and installs fine. Only problem is I cannot find it. There was no install option to add an shortcut to the desktop, there is no C:\ folder, no folder added to Program Files or Program Files (x86). I have Windows 10, 64 bit professional Where did it go? Where is the IDE? You can find out where the executable is with: >>> import sys >>> sys.executable 'C:\\Program Files (x86)\\Python37-32\\python.exe' (Your location may well be different) Peter -- https://mail.python.org/mailman/listinfo/python-list
