Re: Advice to a Junior in High School?
wow! Aren't we getting ahead of ourselves? Well, I'm glad you are beefing up your college knowledge but let's just sit back for a minute and breathe..there, feel better? Now, listen. When I was a freshman and sophomore in high school I was so sure I wanted to be an artist and attend one of the most highly recognized and expensive art schools in the country. I wanted to go to college back east away from my parents. Now I'm a psychology major in community college and I want to attend UCLA! First of all, NEVER SETTLE FOR LESS when it comes to your major. Do what it is true to your heart and never let people say you can't! You can double major if you want to be on the safe side. Compsci isn't an easy thing to do as you know and it's a highly regarded profffession! By the time you graduate college, the world could be a completely different place. But let's just worry about here and now. If you think too much about the future IT WILL DRIVE YOU CRAZY! Trust me, you are doing everything right so far. I applaud your effort but relax and everything will fall into place eventually! I would suggest taking Japanese because you will have to work with them eventually if you do decide to choose compsci as your proffesion. Margaux -- http://mail.python.org/mailman/listinfo/python-list
Re: wxPython and PyGame - do they play well together?
Erik Bethke [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] I am having a great time with python and pygame, and last night I took a long look at the wxPython demo. I think that rocks as well. So now, my question is do wxPython and PyGame work together? I have no personal experience, but based on posts to the Pygame mailing list, also accessible via Google or as newsgroup thru Gmane (where I read it), the answer is yes. The subject of Pygame with guis has been discussed in the past couple of months. I recommend that you read the archives for the recent past and then join the list or subscribe via gmane or google. It is a low volume, low noise, list. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Fuzzy matching of postal addresses
Andrew McLean wrote:
I have a problem that is suspect isn't unusual and I'm looking to see if
there is any code available to help. I've Googled without success.
Basically, I have two databases containing lists of postal addresses and
need to look for matching addresses in the two databases. More
precisely, for each address in database A I want to find a single
matching address in database B.
I had a similar problem to solve a while ago. I can't give you my code,
but I used this paper as the basis for my solution (BibTeX entry from
http://citeseer.ist.psu.edu/monge00adaptive.html):
@misc{ monge-adaptive,
author = Alvaro E. Monge,
title = An Adaptive and Efficient Algorithm for Detecting
Approximately Duplicate
Database Records,
url = citeseer.ist.psu.edu/monge00adaptive.html }
There is a lot of literature--try a google search for approximate
string match--but very little publically available code in this area,
from what I could gather. Removing punctuation, etc., as others have
suggested in this thread, is _not_sufficient_. Presumably you want to
be able to match typos or phonetic errors as well. This paper's
algorithm deals with those problems quite nicely,
--
Aaron Bingham
Application Developer
Cenix BioScience GmbH
--
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Re: [ANN] iCalendar package 0.9
Max M [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] http://www.mxm.dk/products/public/ical/ Any feedback would be welcome. How well do you cope with the crud that real programs generate? Does it work with the different dialects uses out there? Can it at least identify them? The reason why I ask is this would be useful for BitPim. When I wrote the code for doing vCards, I soon found that there wasn't actually a single program out there on Windows, Linux or Mac that actually generated 100% standards conformant vCards. They generally complied with the spirit, but screwed up character encoding, misspelled fields names, didn't do the right thing when commas and semi-colons were present in values etc. I assume the thing happens with ical. Roger -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
Op 2005-01-17, Steve Holden schreef [EMAIL PROTECTED]: Antoon Pardon wrote: Mostly, though, I was trying to say that I found your nitpicking insistence on terminological exactitude, even when giving advice to those new to the language, both inappropriate and tedious in the extreme. I think it is appropiate because not all new to the language are new to programming and even newbees have a right to know how it really is. Otherwise after some time you get experienced users who don't know the fact. In this case for example there are a number of people who flat out assert that muatble dict keys in pyhthon is impossible. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
Antoon Pardon wrote: In this case for example there are a number of people who flat out assert that muatble dict keys in pyhthon is impossible. If you run into any of these folks, please point them to: http://www.python.org/moin/DictionaryKeys It's a pretty good summary of one of the more recent threads on this topic by Peter Maas and myself. If you feel like your point is not covered[1], feel free to add some additional material. (That is, after all, the point of a wiki.) Steve [1] I assume that you feel this way because you have repeated essentially the same point about 5 times in this thread. The wiki is a chance to make your statement once, and then simply post a pointer once per appropriate thread. It might save you some time... -- http://mail.python.org/mailman/listinfo/python-list
inbuilt function buffer()
Hi all, I which context is the inbuilt function buffer() used ? regards, KM -- http://mail.python.org/mailman/listinfo/python-list
Re: Integration with java
Istvan Albert wrote: Joachim Boomberschloss wrote: the code is already written in Python, using the standard libraries and several extension modules One thing to keep in mind is that Jython does not integrate CPython, instead it understands python code directly. So if you have a C extension that works with python it won't work with Jython. Also, Jython is several versions behind CPython, so any Python code that uses generators or new-style division won't work either. My feeling is that if you had a lot of Java code written and wanted to build on that with python Jython would be a better fit than vice versa. I agree. -- http://mail.python.org/mailman/listinfo/python-list
Re: [Python-Dev] Getting rid of unbound methods: patch available
Guido van Rossum wrote: What do people think? (My main motivation for this, as stated before, is that it adds complexity without much benefit.) Something important that came up in my response to Marc-Andre: What about C method implementations which are relying on this typecheck and assuming that 'self' is (nearly) guaranteed to be of the correct type? The string object implementation is where I noticed this assumption being made, but I suspect it would be fairly widespread. Obviously, use of im_func can break such code already, but that's a far cry from having C.f skip the type check. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: extension module, thread safety?
Pierre Barbier de Reuille wrote: With the current CPython, it's very hard to mix Python and C in a multithreading application (with C-threads, not Python-threads). In fact I never really succeeded in that task because of that GIL ! I have a multi-thread application but every bit of Python code must be run into a Python thread. To be more precise, I wanted to be able to call Python code in response to some GUI events, and I didn't want to instanciate a new interpreter for I wanted to be able to access the environment of my main Python interpreter. I don't understand. This is what PyGILState_Ensure and PyGILState_Release are for - so C code can leave the GIL unlocked by default, and only grab it when they want to call into the C/Python API. Regards, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: extension module, thread safety?
Nick Coghlan a écrit : Pierre Barbier de Reuille wrote: With the current CPython, it's very hard to mix Python and C in a multithreading application (with C-threads, not Python-threads). In fact I never really succeeded in that task because of that GIL ! I have a multi-thread application but every bit of Python code must be run into a Python thread. To be more precise, I wanted to be able to call Python code in response to some GUI events, and I didn't want to instanciate a new interpreter for I wanted to be able to access the environment of my main Python interpreter. I don't understand. This is what PyGILState_Ensure and PyGILState_Release are for - so C code can leave the GIL unlocked by default, and only grab it when they want to call into the C/Python API. Regards, Nick. Ok, I wondered why I didn't know these functions, but they are new to Python 2.4 ( and I didn't take the time to look closely at Python 2.4 as some modules I'm working with are still not available for Python 2.4). But if it really allows to call Python code outside a Python thread ... then I'll surely use that as soon as I can use Python 2.4 :) Thanks for the hint :) Pierre -- http://mail.python.org/mailman/listinfo/python-list
Re: wxPython and PyGame - do they play well together?
Thank you, My apologies to all for insufficient googling -Erik -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Raymond Hettinger wrote: [Delaney, Timothy C] Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Length transparency for iterators is not as general as one would expect. I once spent a good deal of effort exploring where it made sense, and I was surprised to find that it only rarely works out. Length transparency is an unexpectedly thorny subject with many dead-ends which precludes a fully general solution such as that proposed by Nick. For a recap of my research, see the docstring for Lib/test/test_iterlen.py . The situation slightly more involved whenever an object allows length mutation during iteration. Ouch. Nice understatement. It's rather unfortunate that we can't make use of the length information even when the source *doesn't* mutate, though. I'll have to think some more to see if I can come up with any concrete ideas for you to shoot down :) Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: Socket and Tkinter Problem
hi, was wondering if you ever got a reply ? Did you mannage to sort this out ? I am wanting todo the same thing - just have a window that connects to a port and displays the data it receives from that port in the window? Thanks Tonino -- http://mail.python.org/mailman/listinfo/python-list
Re: [ANN] iCalendar package 0.9
Roger Binns wrote:
Max M [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED]
http://www.mxm.dk/products/public/ical/
Any feedback would be welcome.
How well do you cope with the crud that real programs generate? Does it work
with the different dialects uses out there? Can it at least identify them?
It depends on how badly the data is screwed up. But generally it should
be able to work on incorrect implementations.
It doesn't care of the spelling of property and parameter names. Though
type conversions will need to be done slightly more manual.
If something like 'dtstart' is misspelled it will not return a datetime
cal.decoded('datestart')
But if you know that it is misspelled you can get it, and convert it
manually like:
from PropertyValues import vDDDType
vDDDType.from_ical(cal['datestart'])
--
hilsen/regards Max M, Denmark
http://www.mxm.dk/
IT's Mad Science
--
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Re: Problem parsing namespaces with xml.dom.minidom
Mike McGavin wrote: is the DOM API an absolute requirement? It wouldn't need to conform to the official specifications of the DOM API, but I guess I'm after some comparable functionality. In particular, I need to be able to parse a namespace-using XML document into some kind of node tree, and then being able to query the tree to select elements based on their namespace and local tag names, and so on. I don't mind if the methods provided don't conform exactly to DOM specifications. sounds like this might be exactly what you need: http://effbot.org/zone/element-index.htm (it's also the fastest and most memory-efficient Python-only parser you can get, but I suppose that's not a problem ;-) /F -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: Raymond Hettinger wrote: [Delaney, Timothy C] Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Length transparency for iterators is not as general as one would expect. I once spent a good deal of effort exploring where it made sense, and I was surprised to find that it only rarely works out. Length transparency is an unexpectedly thorny subject with many dead-ends which precludes a fully general solution such as that proposed by Nick. For a recap of my research, see the docstring for Lib/test/test_iterlen.py . The situation slightly more involved whenever an object allows length mutation during iteration. Ouch. Nice understatement. It's rather unfortunate that we can't make use of the length information even when the source *doesn't* mutate, though. I'll have to think some more to see if I can come up with any concrete ideas for you to shoot down :) Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Problem parsing namespaces with xml.dom.minidom
You've reversed some function parameters. Here's a program that works fine (note that you don't need to set up a SAX parser): from xml.dom import minidom text = '''?xml version=1.0 encoding=UTF-8? xte:xte xmlns:xte='http://www.mcs.vuw.ac.nz/renata/xte' xte:creatoralias/xte:creator xte:dateThu Jan 30 15:06:06 NZDT 2003/xte:date xte:object objectid=object1 Nothing /xte:object /xte:xte ''' # Parse the string into a minidom mydom = minidom.parseString(text) # Look for some elements # This one shouldn't return any (I think). object_el1 = mydom.getElementsByTagName(xte:object) # This one definitely should, at least for what I want. object_el2 = mydom.getElementsByTagNameNS( 'http://www.mcs.vuw.ac.nz/renata/xte',object, ) print '1: ' + str(object_el1) print '2: ' + str(object_el2) -- http://mail.python.org/mailman/listinfo/python-list
Re: Fuzzy matching of postal addresses
You might find these at least periperally useful: http://www.brunningonline.net/simon/blog/archives/001291.html http://www.brunningonline.net/simon/blog/archives/001292.html They refer to address formatting rather than de-duping - but normalising soulds like a useful first step to me. -- Cheers, Simon B, [EMAIL PROTECTED], http://www.brunningonline.net/simon/blog/ -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
On 18 Jan 2005 07:51:00 GMT, Antoon Pardon [EMAIL PROTECTED] wrote:
3 mutating an item in a sorted list *does* *always* cause problems
No, it doesn't. It might cause the list no longer to be sorted, but
that might or might no be a problem.
More specific the Decimal class is mutable and usable as dict key.
Decimal objects are immutable, so far as I know.
from decimal import Decimal
spam = Decimal('1.2')
eggs = spam
eggs is spam
True
eggs += 1
eggs is spam
False
--
Cheers,
Simon B,
[EMAIL PROTECTED],
http://www.brunningonline.net/simon/blog/
--
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Re: lambda
Op 2005-01-18, Simon Brunning schreef [EMAIL PROTECTED]:
On 18 Jan 2005 07:51:00 GMT, Antoon Pardon [EMAIL PROTECTED] wrote:
3 mutating an item in a sorted list *does* *always* cause problems
No, it doesn't. It might cause the list no longer to be sorted, but
that might or might no be a problem.
Than in the same vain I can say that mutating a key in a dictionary
doesn't always cause problems either. Sure it may probably make a
key unaccessible directly, but that might or might not be a problem.
More specific the Decimal class is mutable and usable as dict key.
Decimal objects are immutable, so far as I know.
from decimal import Decimal
spam = Decimal('1.2')
eggs = spam
eggs is spam
True
eggs += 1
eggs is spam
False
from decimal import Decimal
spam = Decimal('1.2')
egg = spam
spam._int = (1, 3)
spam
Decimal(1.3)
spam is egg
True
--
Antoon Pardon
--
http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Antoon Pardon wrote: Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: Raymond Hettinger wrote: [Delaney, Timothy C] Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Length transparency for iterators is not as general as one would expect. I once spent a good deal of effort exploring where it made sense, and I was surprised to find that it only rarely works out. Length transparency is an unexpectedly thorny subject with many dead-ends which precludes a fully general solution such as that proposed by Nick. For a recap of my research, see the docstring for Lib/test/test_iterlen.py . The situation slightly more involved whenever an object allows length mutation during iteration. Ouch. Nice understatement. It's rather unfortunate that we can't make use of the length information even when the source *doesn't* mutate, though. I'll have to think some more to see if I can come up with any concrete ideas for you to shoot down :) Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. Since it doesn't yet optimize 2+5 to a constant-folded 7 you should realize that you are suggesting a large increase in the compiler's analytical powers. I agree it would be nice under certain circumstances, but don't forget that unlike list comprehensions (for which it would be even nicer) the whole point of generator expressions is often to defer the generation of the individual items until they are required and thereby relieve stress on memory. As an edge case to demonstrate the point, what about a constant but infinite sequence? regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: Central New Jersey PIG Meeting -- Python Interest Group In Princeton PIG/IP
Yes Jay. PIG/IP meetings are publicly open with no RSVP necessary. Most of the folks coming are LUG/IP members, as I am and the location is the same as LUG/IP meetings. We haven't formalized the group's affiliation yet. -- Jon -- http://mail.python.org/mailman/listinfo/python-list
Re: Integration with java
Dan Bishop wrote: Istvan Albert wrote: Joachim Boomberschloss wrote: the code is already written in Python, using the standard libraries and several extension modules One thing to keep in mind is that Jython does not integrate CPython, instead it understands python code directly. So if you have a C extension that works with python it won't work with Jython. Also, Jython is several versions behind CPython, so any Python code that uses generators or new-style division won't work either. My feeling is that if you had a lot of Java code written and wanted to build on that with python Jython would be a better fit than vice versa. I agree. Also let's not forget that the PSF has funded a project that's intended to help Jython get up to the curve - see http://www.python.org/psf/grants/Jython_PSF_Grant_Proposal.pdf. If that project succeeds, and if 2.5 development *does* focus mostly on the library, there's a sporting chance that Jython can be fully up to date for the 2.5 release. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
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Re: lambda
Antoon Pardon wrote: More specific the Decimal class is mutable and usable as dict key. It's *meant* to be immutable though. The fact that we used __slots__ instead of __setattr__ to implement the immutability, so you *can* overwrite the slot variables if you really want to is merely an artifact of the current Python implementation. The limited mutability bug will disappear in Python 2.5, so it's not a good example of a 'mutable' dict key (especially given that the only way to mutate it is to modify private variables directly). And, as I've stated previously, if the issue of sane mutable keys in dictionaries and sets really bugs you so much - implement identity_dict and identity_set in C and lobby for their inclusion in the collections module. On the more general point of don't use mutable objects with non-identity based comparisons as dictionary keys, try teaching students for a while (or listen to those who have): When stating useful general principles, it is never, ever worth it to get into the quibbly little details about exceptions to the principle. If students ask, admit that they exist, but point out that the exceptions are rare, and not worth worrying about at that point in their learning. Only when one is aware of the reasons for a principle, can one be aware of good reasons not to follow it :) Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. This won't ever happen in python - at least not in python otherwise similar to the one we know... The thing you're after is known as common subexpression elemination and can only be done in purely functional languages. While that certainly is an interesting property of a language, it e.g. forbids functions like time.time() - a too huge paradigm shift for python. -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Op 2005-01-18, Steve Holden schreef [EMAIL PROTECTED]: Antoon Pardon wrote: Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: Raymond Hettinger wrote: [Delaney, Timothy C] Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Length transparency for iterators is not as general as one would expect. I once spent a good deal of effort exploring where it made sense, and I was surprised to find that it only rarely works out. Length transparency is an unexpectedly thorny subject with many dead-ends which precludes a fully general solution such as that proposed by Nick. For a recap of my research, see the docstring for Lib/test/test_iterlen.py . The situation slightly more involved whenever an object allows length mutation during iteration. Ouch. Nice understatement. It's rather unfortunate that we can't make use of the length information even when the source *doesn't* mutate, though. I'll have to think some more to see if I can come up with any concrete ideas for you to shoot down :) Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. Since it doesn't yet optimize 2+5 to a constant-folded 7 you should realize that you are suggesting a large increase in the compiler's analytical powers. Well I can dream, cant I? I agree it would be nice under certain circumstances, but don't forget that unlike list comprehensions (for which it would be even nicer) the whole point of generator expressions is often to defer the generation of the individual items until they are required and thereby relieve stress on memory. As an edge case to demonstrate the point, what about a constant but infinite sequence? Maybe I was not clear enough. I meant to limit it to cases such as lst = list(genexp) tpl = tuple(genexp) Since in such cases the object is build in memory any way, I don't think it would be a problem of having them prebuilt in memory, or am I missing something? -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: List problems in C code ported to Python
On Mon, 17 Jan 2005 15:28:56 GMT, Lucas Raab [EMAIL PROTECTED] wrote:
Lucas Raab wrote:
I'm done porting the C code, but now when running the script I
continually run into problems with lists. I tried appending and
extending the lists, but with no avail. Any help is much appreciated
Please see both the Python and C code at
http://home.earthlink.net/~lvraab. The two files are ENIGMA.C and engima.py
TIA
OK, here's the Python code and the corresponding C code:
def init_mach():
import string
#setup rotor data
i=1
j=0
for j in j26, j+1:
I urge you to explore interactively. And do it line by line
(and even expression by expression when you get mystifying results) until you
are more familiar with the language.
E.g., what do you think the values of j will be here?
j=0
for j in j26, j+1: print j,
...
True 1
Surprised?
j26, j+1
(True, 2)
Hm, surprised at the 2 here?
j=0
j26, j+1
(True, 1)
IOW, your 'for' line was equivalent to iterating through a length-2 tuple
for j in (True, 1): # since if j is 0, j26 is True, and j+1 is 1
What you probably wanted was j starting with 0 and ending with 25, which you
get by
for j in xrange(26): print j,
...
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
(The comma at the end of the print statement is to get a space before
the next output instead of a newline).
data[4],[j] = (ref_rotor[j] - 'A'+26) % 26
Had you tried an interactive experiment, you would have had some real questions
to ask ;-)
j=0
for j in xrange(26):
... data[4],[j] = (ref_rotor[j] - 'A'+26) % 26
...
Traceback (most recent call last):
File stdin, line 2, in ?
NameError: name 'ref_rotor' is not defined
Ok, fix that with something
ref_rotor = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' # something legal
j=0
for j in xrange(26):
... data[4],[j] = (ref_rotor[j] - 'A'+26) % 26
...
Traceback (most recent call last):
File stdin, line 2, in ?
TypeError: unsupported operand type(s) for -: 'str' and 'str'
You might have had to ask at this point what that meant, but you could get
closer by
trying the expressions and their terms:
(ref_rotor[j] - 'A'+26) % 26
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unsupported operand type(s) for -: 'str' and 'str'
Pare it down
(ref_rotor[j] - 'A'+26)
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unsupported operand type(s) for -: 'str' and 'str'
Check pieces
j
0
ref_rotor[j]
'A'
Substitute to make painfully clear
('A' - 'A'+26)
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unsupported operand type(s) for -: 'str' and 'str'
('A' - 'A')
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unsupported operand type(s) for -: 'str' and 'str'
What is 'A' ?
type('A')
type 'str'
Hm, characters are strings, not char types that are directly type compatible
with int. It takes a conversion. To get from single-char string to its integer
code
and back:
ord('A')
65
chr(65)
'A'
Another experiment:
ord('AB')
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: ord() expected a character, but string of length 2 found
Now you are in a position to use ord, and get a little further:
j=0
for j in xrange(26):
... data[4],[j] = (ord(ref_rotor[j]) - ord('A')+26) % 26
...
Traceback (most recent call last):
File stdin, line 2, in ?
TypeError: unpack non-sequence
Was the right hand side a problem?
j
0
(ord(ref_rotor[j]) - ord('A')+26) % 26
0
Apparently not, so what it was trying to do was
data[4],[j] = 0
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unpack non-sequence
What was it trying to unpack? And why?
Well, you might have known if you had been through the tutorial, but at least
you would have had a specific question about a specific error at this point.
Note:
a, b = 0
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: unpack non-sequence
I.e., when you have commas (or even one) on the left hand side of an assignment,
that is asking python to unpack a sequence on the right hand side and assign to
corresponding items on the left. So e.g.,
a, b = 0, 1
will unpack the tuple formed by 0, 1
a
0
b
1
You can unpack any sequence of the same length, and strings happen to be
sequences:
a,b = 'XY'
a
'X'
b
'Y'
Ok, enough of that. The comma was obviously a problem so, try it without:
data[4][j] = 0
Traceback (most recent call last):
File stdin, line 1, in ?
NameError: name 'data' is not defined
I could go on, but IMO if you expect help, you should do your part, and at least
post code that you have tried and which compiles or runs up to the point where
it shows an error that you need help with.
And show a verbatim copy/paste from your interactive session, not uncompilable
and obviously
Re: generator expressions: performance anomaly?
Antoon Pardon wrote: Op 2005-01-18, Steve Holden schreef [EMAIL PROTECTED]: Antoon Pardon wrote: Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: Raymond Hettinger wrote: [Delaney, Timothy C] Nick's other suggestion - that genexps propagate __len__ - might still be interesting. Of course, it would only be applicable for unconditional genexps(i.e. no if clause). Length transparency for iterators is not as general as one would expect. I once spent a good deal of effort exploring where it made sense, and I was surprised to find that it only rarely works out. Length transparency is an unexpectedly thorny subject with many dead-ends which precludes a fully general solution such as that proposed by Nick. For a recap of my research, see the docstring for Lib/test/test_iterlen.py . The situation slightly more involved whenever an object allows length mutation during iteration. Ouch. Nice understatement. It's rather unfortunate that we can't make use of the length information even when the source *doesn't* mutate, though. I'll have to think some more to see if I can come up with any concrete ideas for you to shoot down :) Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. Since it doesn't yet optimize 2+5 to a constant-folded 7 you should realize that you are suggesting a large increase in the compiler's analytical powers. Well I can dream, cant I? I agree it would be nice under certain circumstances, but don't forget that unlike list comprehensions (for which it would be even nicer) the whole point of generator expressions is often to defer the generation of the individual items until they are required and thereby relieve stress on memory. As an edge case to demonstrate the point, what about a constant but infinite sequence? Maybe I was not clear enough. I meant to limit it to cases such as lst = list(genexp) tpl = tuple(genexp) Since in such cases the object is build in memory any way, I don't think it would be a problem of having them prebuilt in memory, or am I missing something? Perhaps it had been better if that kind of functionality were implemented with a different syntax, I don't know enough about how the python interpreter works but perhaps it should be possible to execute some expressions with genexp syntax when compiling to bytecode. That should be a quite trivial extension. examples using '' list-comp/genexp syntax '': lst = i for i in range(100) or perhaps lst = list(i for i in range(100)) Would result in the same bytecode as this expression lst = [0, 1, 2, 3, ..., 98, 99] It could be called static list comprehensions. But if it is a usefull extension is another dicussion. ola -- http://mail.python.org/mailman/listinfo/python-list
Re: how to find site-packages path (Michael Hoffman) - use distutils
Why would you want to copy any *.pyc instead of compiling them on site? I know that sounds terrible to the open source community, but I do not intend to release the source code for my product - pls go to philippecmartin.com/applications.html for my _small_ contributions :-)) Regards, Philippe -- *** Philippe C. Martin SnakeCard LLC www.snakecard.com *** -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
lst = list(genexp) tpl = tuple(genexp) Since in such cases the object is build in memory any way, I don't think it would be a problem of having them prebuilt in memory, or am I missing something? Yes. Consider this: lst = list(time.time() for i in xrange(10)) tpl = tuple(time.time() for i in xrange(10)) -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: news feed problem -- anyone else?
On 17 Jan 2005 16:48:24 EST, Tim Daneliuk [EMAIL PROTECTED] wrote: Bengt Richter wrote: I can see postings on google, but my news service is having a problem since sometime during the weekend. Can get old stuff from other n.g., but no new. Wondering whether I'll see this via google. Regards, Bengt Richter Bengt - I've had very good luck using the following *free* newsfeed: http://individual.net/ HTH, Thanks, I can see this via normal news now. But that looks good. Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Diez B. Roggisch wrote: lst = list(genexp) tpl = tuple(genexp) Since in such cases the object is build in memory any way, I don't think it would be a problem of having them prebuilt in memory, or am I missing something? Yes. Consider this: lst = list(time.time() for i in xrange(10)) tpl = tuple(time.time() for i in xrange(10)) Would it be a bad solution to make that a list or tuple of ten time.time() calls, you could also restrict what theese prebuilding sequenses could contain, or perhaps try to prebuild them, and then fail if it's impossible. -- -- Ola Natvig [EMAIL PROTECTED] infoSense AS / development -- http://mail.python.org/mailman/listinfo/python-list
[wxpython] exclude files in a wx.FileDialog?
Hello, Is it possible to exclude certain files in a wx.FileDialog, so that the user won't see them and can't select them with the mouse in de File open window? I was thinking of somehow extending the class FileDialog(Dialog) in the wx module _windows.py to a subclass, but I'm not sure how to do that (if feasible). cheers -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Would it be a bad solution to make that a list or tuple of ten time.time() calls, you could also restrict what theese prebuilding sequenses could contain, or perhaps try to prebuild them, and then fail if it's impossible. I don't fully understand what you mean. Restricting them would mean to add static declarations that say I return the same whenever you call me - which is even more than the already fragile const declaration of c++ allows. And for your second suggestion - how exactly do you check for failing? Generating 2 elements and checking if they are equal to the first two of the old list? What about overloaded __cmp__/__eq__, or just the last element differing? This problem is too complex to solve automatically - domain knowledge is needed. As the code Antoon presented also suggests the simple solution: lst = list(time.time() for i in xrange(10)) tpl = tuple(lst) I don't see why this is a desirable feature at all. Keep in mind that putting statements or even stackframes between those two statements above utterly complicates things. And we even didn't dig into the dynamic features of python that for example make it possible to alter time.time like this time.time = random.random() so that it behaves totally different - while the syntactically equivalence still holds. No chance of catching that. -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: Antoon Pardon wrote: More specific the Decimal class is mutable and usable as dict key. It's *meant* to be immutable though. The fact that we used __slots__ instead of __setattr__ to implement the immutability, so you *can* overwrite the slot variables if you really want to is merely an artifact of the current Python implementation. The limited mutability bug will disappear in Python 2.5, so it's not a good example of a 'mutable' dict key (especially given that the only way to mutate it is to modify private variables directly). And, as I've stated previously, if the issue of sane mutable keys in dictionaries and sets really bugs you so much - implement identity_dict and identity_set in C and lobby for their inclusion in the collections module. I'm not bugged by its absence in Python. I'm bugged by the attitude about them. But anyway I'm thinking about implementing a safe dictionary that will copy whenever it would otherwise allow the risk of mutating a key. On the more general point of don't use mutable objects with non-identity based comparisons as dictionary keys, try teaching students for a while (or listen to those who have): What kind of students? I have implemented a hash table when I was a student and its implementation allowed the use of 'mutable' objects as a key without a problem. It simply always made copies when appropiate and didn't allow external access to the keys. So although the key objects were 'mutable' there was no way a user could accidently mutate a key. So don't use a mutable as a dictionary key isn't so much a dictionary limitation in general but a specific limitation of the python implementation. And yes I understand, the current implenatation is the result of the fact that the same dictionaries are used internally for variables in scopes and attributes in objects and the fact that no copies are involved gives a boost to performance. But it could be argued that providing these same dictionaries with those semantics to the users was a premature optimisation. When stating useful general principles, it is never, ever worth it to get into the quibbly little details about exceptions to the principle. If students ask, admit that they exist, but point out that the exceptions are rare, and not worth worrying about at that point in their learning. But don't use mutable keys is not a general principle. It is a principle introduced by the limitations of the python implementations. I don't like it when a good rule of thumb because of implementation limitations is sold as a general principle. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050118 keyed list
Xah Lee [EMAIL PROTECTED] wrote: : # the syntax of keyed list in Perl is too complex : # to be covered in a short message. You've got to be joking. You couldn't even muster enough skill to provide Perl equivalents for the four simple Python statements you showed? : # see perldoc perldata for an unix-styled course. It's good to see your opinion on the _fantastic incompetent writting_[1] of Perl's documentation has changed enough that you can recommend it to novices. [1]Message-ID: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: strange note in fcntl docs
On Mon, Jan 17, 2005 at 09:54:46PM -0600, Skip Montanaro wrote: John And, even if they were, the note is *still* wrong and misleading: John fcntl is available on Windows, and os.open's flags won't be. Does this read better? [snip] yes, and it takes me back to considering why file objects don't have methods suck as lock, stat and mmap where those calls are available through other mechanisms... -- John Lenton ([EMAIL PROTECTED]) -- Random fortune: Yo mando a mi gato y mi gato manda a su rabo. signature.asc Description: Digital signature -- http://mail.python.org/mailman/listinfo/python-list
Re: [wxpython] exclude files in a wx.FileDialog?
On 18 Jan 2005 13:23:24 GMT, John Field [EMAIL PROTECTED] wrote: Hello, Is it possible to exclude certain files in a wx.FileDialog, so that the user won't see them and can't select them with the mouse in de File open window? I was thinking of somehow extending the class FileDialog(Dialog) in the wx module _windows.py to a subclass, but I'm not sure how to do that (if feasible). cheers wx.FileDialog is only a wrapper for the api FileDialog (at least this applies for windows) and therefore it is not possible to derive from it. Really exclude, I think, is not possible. You can put a mask wx.FileDialog(...wildcard = BMP files (*.bmp)|*.bmp|GIF files (*.gif)|*.gif) Otherwise you have to create your own FileDialog. -- Franz Steinhaeusler -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
On Tue, 18 Jan 2005 07:12:18 -0500, Steve Holden [EMAIL PROTECTED] wrote:
Since it doesn't yet optimize 2+5 to a constant-folded 7 you should
realize that you are suggesting a large increase in the compiler's
analytical powers.
As in interesting aside to this, you might be interested to know that
PHP has constant folding, allowing you to do things like
$foo = 7+9; and have it generate bytecode that is let 'foo' equal 16
or somesuch.
PHP achieves this by having a subset of expression parsing available
only for situations where a folded constant is allowed.
i.e.
class Foo {
var $bar = 1+4; /* this constant is folded */
}
static_scalar: /* compile-time evaluated scalars */
common_scalar | T_STRING | '+' static_scalar |
'-' static_scalar | T_ARRAY '(' static_array_pair_list ')'
;
common_scalar:
/* all numbers, strings-not-containing-variable-interpolation and a
few hacks like __FILE__ and __LINE__ */
;
As you can see from the grammar, there are any number of ways this can break.
i.e.
Parse Error, * isn't allowed:
class Foo { var $bar = 60*60*24; }
Parse Error, neither is anything except + and -:
class Foo { var $bar = 256 18; }
Parse Error, and definately not variables:
$baz = 12;
class Foo { var $bar = $baz*2; }
I compute 60*60*24 every time around the loop:
foreach ($myarray as $value) { $x = 60*60*24*$value; }
Thankful, Former PHP Programmer,
Stephen Thorne.
--
http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Diez B. Roggisch wrote: Would it be a bad solution to make that a list or tuple of ten time.time() calls, you could also restrict what theese prebuilding sequenses could contain, or perhaps try to prebuild them, and then fail if it's impossible. I don't fully understand what you mean. Restricting them would mean to add static declarations that say I return the same whenever you call me - which is even more than the already fragile const declaration of c++ allows. And for your second suggestion - how exactly do you check for failing? Generating 2 elements and checking if they are equal to the first two of the old list? What about overloaded __cmp__/__eq__, or just the last element differing? This problem is too complex to solve automatically - domain knowledge is needed. As the code Antoon presented also suggests the simple solution: lst = list(time.time() for i in xrange(10)) tpl = tuple(lst) I don't see why this is a desirable feature at all. Keep in mind that putting statements or even stackframes between those two statements above utterly complicates things. And we even didn't dig into the dynamic features of python that for example make it possible to alter time.time like this time.time = random.random() so that it behaves totally different - while the syntactically equivalence still holds. No chance of catching that. My thoughts where to let the 'leftmost' section of the expression to be intact so that any of the dynamic things done to this part, i.e. replacing time.time with random.random are taken into consideration. What can be done is to extract the expression into a loopless structure lst = list(time.time() for i in xrange(10)) would be compiled to the bytecode version of: lst = [time.time(), time.time(), time.time(), time.time() ...] Then time.time can do whatever it wants to. It's the (x)range function that we need to enshure returns the same values in every execution. This *IS* a useless feature, but I think it's possible to make it work. ola -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
My thoughts where to let the 'leftmost' section of the expression to be intact so that any of the dynamic things done to this part, i.e. replacing time.time with random.random are taken into consideration. What can be done is to extract the expression into a loopless structure lst = list(time.time() for i in xrange(10)) would be compiled to the bytecode version of: lst = [time.time(), time.time(), time.time(), time.time() ...] Then time.time can do whatever it wants to. It's the (x)range function that we need to enshure returns the same values in every execution. This *IS* a useless feature, but I think it's possible to make it work. What makes the leftmost expression different from the iterable returning expression inside the for? The same arguments apply there. -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Op 2005-01-18, Diez B. Roggisch schreef [EMAIL PROTECTED]: Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. This won't ever happen in python - at least not in python otherwise similar to the one we know... The thing you're after is known as common subexpression elemination and can only be done in purely functional languages. While that certainly is an interesting property of a language, it e.g. forbids functions like time.time() - a too huge paradigm shift for python. I don't see how generating byte code for a = 9; when seeing the expression a = 3 + 6, would be a problem for non-functional languages. I agree that things like [time.time() for i in xrange(10)] shouldn't be pregenerated and that the problem is more complicated as I thought. But during compilation the compilor could do an anlysis of the code do determine whether there are side effects or not. If the compilor then would store a code in the byte code for functions that are guaranteed side-effect free and only pregenerated objects generated by expressions with no side-effect, some common subexpression elimination could be done even in a non-functional language. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
MemoryError with parser.suite and wrong encoding declaration
Hi there !
I've noticed the following problem with python = 2.3 (actually 2.3.4 and
2.4):
[EMAIL PROTECTED]:test$ python
Python 2.3.4 (#2, Sep 24 2004, 08:39:09)
[GCC 3.3.4 (Debian 1:3.3.4-12)] on linux2
Type help, copyright, credits or license for more information.
import parser
parser.suite('# -*- coding: IBO-8859-1 -*-')
Traceback (most recent call last):
File stdin, line 1, in ?
MemoryError
parser.suite('# -*- coding: ISO-8859-1 -*-')
parser.st object at 0xb7e5e060
Shouldn't parser.suite just ignore the wrong encoding declaration, or at
least raise a more appropriate exception. IMHO the first solution
would be better, since that's the behaviour of the (C) python interpreter.
--
Sylvain Thénault LOGILAB, Paris (France).
http://www.logilab.com http://www.logilab.fr http://www.logilab.org
--
http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
What makes the leftmost expression different from the iterable returning expression inside the for? The same arguments apply there. It's not different, but it's a requirement that the iterable returns the same data every time. I know that anyone can type range = fancyRange and make this return a random number of random items. But if that happens the expression cannot be transformed into a static list / tuple. Thats obvious. -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
On Mon, Jan 17, 2005 at 03:20:01PM +, Antoon Pardon wrote: Op 2005-01-17, John Lenton schreef [EMAIL PROTECTED]: knowledgeable and experienced users know when to ignore the rules. Then why seems there to be so few acknowledgement that these rules may indeed be broken by users. My experience is that anyone who suggests so runs the risk of being branded a (python) heretic. First you learn the basics, then you think you're knowledgeable and experienced, then you learn the rules, then you become one with the rules, and then you may break them. Most people suggesting these things haven't gotten past step #3. Using Craig's parallel to C's goto, every and all newbie using gotos should be lambasted: even if the use might be correct for the problem they are trying to solve, the reasons for its correctness are far too complex for them to grasp. But really, in practically any system, the rules are generalizations, and they exist because the particulars are too delicate to trust the unexperienced. The small print is unprintable. He dicho. -- John Lenton ([EMAIL PROTECTED]) -- Random fortune: Yo siempre seré el futuro Nobel. Debe ser una tradición escandinava. -- Jorge Luis Borges. (1899-1986) Escritor argentino. signature.asc Description: Digital signature -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda
Antoon Pardon wrote: Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: [...] But don't use mutable keys is not a general principle. It is a principle introduced by the limitations of the python implementations. Sorry, but it *is* a general principle, adduced from the potential pitfalls available to inexperienced programmers when breaking the principle. I don't like it when a good rule of thumb because of implementation limitations is sold as a general principle. So, since you are so good at nit-picking, perhaps you will explain the difference between rule of thumb and general principle. preferably-in-less-than-three-thousand-words-ly y'rs - steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Stephen Thorne wrote:
On Tue, 18 Jan 2005 07:12:18 -0500, Steve Holden [EMAIL PROTECTED] wrote:
Since it doesn't yet optimize 2+5 to a constant-folded 7 you should
realize that you are suggesting a large increase in the compiler's
analytical powers.
As in interesting aside to this, you might be interested to know that
PHP has constant folding, allowing you to do things like
$foo = 7+9; and have it generate bytecode that is let 'foo' equal 16
or somesuch.
PHP achieves this by having a subset of expression parsing available
only for situations where a folded constant is allowed.
i.e.
class Foo {
var $bar = 1+4; /* this constant is folded */
}
static_scalar: /* compile-time evaluated scalars */
common_scalar | T_STRING | '+' static_scalar |
'-' static_scalar | T_ARRAY '(' static_array_pair_list ')'
;
common_scalar:
/* all numbers, strings-not-containing-variable-interpolation and a
few hacks like __FILE__ and __LINE__ */
;
As you can see from the grammar, there are any number of ways this can break.
i.e.
Parse Error, * isn't allowed:
class Foo { var $bar = 60*60*24; }
Parse Error, neither is anything except + and -:
class Foo { var $bar = 256 18; }
Parse Error, and definately not variables:
$baz = 12;
class Foo { var $bar = $baz*2; }
I compute 60*60*24 every time around the loop:
foreach ($myarray as $value) { $x = 60*60*24*$value; }
Thankful, Former PHP Programmer,
Stephen Thorne.
Yes, well, this just goes to confirm my belief that PHP isn't a
programming language. I am always amazed at what's been achieved with it
(though I sometimes wonder at what cost).
You probably already know that sensible compiled language systems have
used constant folding since time immemorial, but Python has always
eschewed it. That's what comes of being a pragmatist's language: if such
optimizations really are required the programmer is expected to perform
them.
and-ninety-nine-point-nine-nine-percent-of-the-time-they-aren't-ly y'rs
- steve
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/
Holden Web LLC +1 703 861 4237 +1 800 494 3119
--
http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
I don't see how generating byte code for a = 9; when seeing the expression a = 3 + 6, would be a problem for non-functional languages. Most probably. But I don't see much code of that type that it would be worth optimizing for, either. The cost for re-evaluation such an expression doesn't really account for any performance problems you hit - in python, of course. See this: [EMAIL PROTECTED]:/usr/lib/python2.3$ python timeit.py -c [4*5 for i in xrange(1)] 100 loops, best of 3: 5.5e+03 usec per loop [EMAIL PROTECTED]:/usr/lib/python2.3$ python timeit.py -c [20 for i in xrange(1)] 100 loops, best of 3: 4.3e+03 usec per loop Now of course the longer the expressions get, the more time it costs - but how many long arithmetical expression of constant evaluation value do you have? I agree that things like [time.time() for i in xrange(10)] shouldn't be pregenerated and that the problem is more complicated as I thought. But during compilation the compilor could do an anlysis of the code do determine whether there are side effects or not. If the compilor then would store a code in the byte code for functions that are guaranteed side-effect free and only pregenerated objects generated by expressions with no side-effect, some common subexpression elimination could be done even in a non-functional language. This analysis would only be possible for the most primitive of examples, the reason beeing that due to the dynamic features syntactically equivalent expressions can have totally different semantics. So its not really worth the effort. -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Antoon Pardon wrote: Op 2005-01-18, Diez B. Roggisch schreef [EMAIL PROTECTED]: Something else I was thinking about. I think it would be nice if the python compilor could figure out whether a genexp in a list or tuple expression always generates the same list or tuple and then instead of generating code would generate the list or tuple in place. This won't ever happen in python - at least not in python otherwise similar to the one we know... The thing you're after is known as common subexpression elemination and can only be done in purely functional languages. While that certainly is an interesting property of a language, it e.g. forbids functions like time.time() - a too huge paradigm shift for python. I don't see how generating byte code for a = 9; when seeing the expression a = 3 + 6, would be a problem for non-functional languages. I agree that things like [time.time() for i in xrange(10)] shouldn't be pregenerated and that the problem is more complicated as I thought. But during compilation the compilor could do an anlysis of the code do determine whether there are side effects or not. If the compilor then would store a code in the byte code for functions that are guaranteed side-effect free and only pregenerated objects generated by expressions with no side-effect, some common subexpression elimination could be done even in a non-functional language. Indeed, and it has been, which is a matter of well-recorded history. Constant folding has been used since the early Fortran compilers. But you've already stated that the problem is more complicated than you thought. I presume you are already prepared to bail on any function that calls into external modules or extensions, since clearly nothing can be known about their behaviors vis a vis side effects. Python is *designed* as a dynamic language. I wish you would embrace this aspect rather than continually trying to shoehorn it into a static straitjacket. Efficiency is good. Flexibility is better. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050118 keyed list
Xah Lee wrote:
© # in perl, keyed-list is done like this:
Just FYI: those thingies are called hashes. The legacy name would be
associative array.
© %a = ('john',3, 'mary', 4, 'jane', 5, 'vicky',7);
© use Data::Dumper qw(Dumper);
© print Dumper \%a;
Wow, my compliments. The very first time that using Data::Dumper actually
may do something useful (formats the data more nicely). Still, why you are
passing a reference is beyond me.
© # the syntax of keyed list in Perl is too complex
© # to be covered in a short message.
Excuse me? If (using the same examples as for your Python section)
print Mary is $a{mary};
delete $a{vicky}; print %a;
print keys(%a);
exists $a{mary};
is too complex for your to cover, then I strongly suggest you stop posting
your explanations.
© # see perldoc perldata for an unix-styled course.
Excuse me? Do you mind explaining where exactly perldata is Unix-styled?
jue
--
http://mail.python.org/mailman/listinfo/python-list
Re: lambda
Op 2005-01-18, Steve Holden schreef [EMAIL PROTECTED]: Antoon Pardon wrote: Op 2005-01-18, Nick Coghlan schreef [EMAIL PROTECTED]: [...] But don't use mutable keys is not a general principle. It is a principle introduced by the limitations of the python implementations. Sorry, but it *is* a general principle, adduced from the potential pitfalls available to inexperienced programmers when breaking the principle. But if these inexperienced programmers would have used dictionaries that were implemented more safely, those pitfalls would have been avoided. So are the pitfalls caused by breaking the principle or by using an unsafe dictionary implementation? I don't like it when a good rule of thumb because of implementation limitations is sold as a general principle. So, since you are so good at nit-picking, perhaps you will explain the difference between rule of thumb and general principle. A rule of thumb is context sensitive. If circumstances change, so do the rules of thumb. Principles have a broader field of application. IMO there is nothing principally wrong with using a mutable object as a dictionary key. But avoiding doing so is a good rule of thumb if you have a python-like implementation of a dictionary. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
bind error!!!!!
hi.. my code was working pretty well until yesterday.suddenly it started giving me bind error: address already in use. but i have logged out and again logged in, but still the problem is not solved can somebody give me solution for this thankx perrin -- http://mail.python.org/mailman/listinfo/python-list
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Re: generator expressions: performance anomaly?
Op 2005-01-18, Steve Holden schreef [EMAIL PROTECTED]: Python is *designed* as a dynamic language. I wish you would embrace this aspect rather than continually trying to shoehorn it into a static straitjacket. Efficiency is good. Flexibility is better. Flexibility is better? IMO flexibilty implies more than one way to do things. But that is a big no no here in c.l.py. I also see a lot of remarks that go: Don't do this! when some of the more dynamic aspects are talked about, because there are security risks involved. One of the results was that I ended up writing a parser for some kind of game instead of just dumping the structure in textual form and doing an eval of the file when reading it in. But if I need a parser I could just as well used a static language. I'm beginning to guess the dynamic aspect of python is overrated. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
RE: bind error!!!!!
Title: RE: bind error! [Perrin Aybara] #- my code was working pretty well until yesterday.suddenly it started #- giving me bind error: address already in use. #- but i have logged out and again logged in, but still the #- problem is not solved #- can somebody give me solution for this Do you really think that somebody could help you with the information that you're giving? You should read this: http://www.catb.org/~esr/faqs/smart-questions.html Regards, . Facundo Bitácora De Vuelo: http://www.taniquetil.com.ar/plog PyAr - Python Argentina: http://pyar.decode.com.ar/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ADVERTENCIA. La información contenida en este mensaje y cualquier archivo anexo al mismo, son para uso exclusivo del destinatario y pueden contener información confidencial o propietaria, cuya divulgación es sancionada por la ley. Si Ud. No es uno de los destinatarios consignados o la persona responsable de hacer llegar este mensaje a los destinatarios consignados, no está autorizado a divulgar, copiar, distribuir o retener información (o parte de ella) contenida en este mensaje. Por favor notifíquenos respondiendo al remitente, borre el mensaje original y borre las copias (impresas o grabadas en cualquier medio magnético) que pueda haber realizado del mismo. Todas las opiniones contenidas en este mail son propias del autor del mensaje y no necesariamente coinciden con las de Telefónica Comunicaciones Personales S.A. o alguna empresa asociada. Los mensajes electrónicos pueden ser alterados, motivo por el cual Telefónica Comunicaciones Personales S.A. no aceptará ninguna obligación cualquiera sea el resultante de este mensaje. Muchas Gracias. -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
Antoon Pardon wrote: Op 2005-01-18, Steve Holden schreef [EMAIL PROTECTED]: Python is *designed* as a dynamic language. I wish you would embrace this aspect rather than continually trying to shoehorn it into a static straitjacket. Efficiency is good. Flexibility is better. Flexibility is better? IMO flexibilty implies more than one way to do things. But that is a big no no here in c.l.py. Become one with the language. I also see a lot of remarks that go: Don't do this! when some of the more dynamic aspects are talked about, because there are security risks involved. One of the results was that I ended up writing a parser for some kind of game instead of just dumping the structure in textual form and doing an eval of the file when reading it in. But if I need a parser I could just as well used a static language. Wow, you mean you actually *took* some advice? :-) Perhaps this whole thing has arisen because you feel you were badly advised. It looks as though your programming skill level might have been underestimated. Your ability to wring an argument to a merciless death could never be. I'm beginning to guess the dynamic aspect of python is overrated. You shouldn't have to guess, and it isn't. Certain of its dynamic aspects do demand a certain care rather than casual usage, however, which leads to rules of thumb like don't use mutables as dictionary keys. Yes, of course you can, but to a newbie your behavior (it seems to me) is a bit like this: Me (to newbie): ... And, of course, you want to be careful not to shoot yourself in the foot. You: :Well, actually, if you use a .22 and aim very carefully between the big toe and its neighbor there's a 96% chance that you will only suffer serious burns. So, please understand, I'm not trying to say that (most of) your utterances are untrue, or question your knowledge of the Python environment. I'm just trying to bring the day closer when you will be able to watch me write something that's only 99% true and happily walk away without writing a thousand-word essay on the remaining 1% case. This anal behavior is unlikely to win friends and influence people. Anyway, I've just about had my say on this topic now. I'm left with the uncomfortable feeling that having led you patiently (or at least as patiently as I can) down to the water, I will now have to watch you die of thirst rather than take a well-deserved drink. Life's too short. I'm going to stop disagreeing with you now, even if this means stopping communicating with you. I'm sure you won't miss my crotchety ramblings anyway. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: bind error!!!!!
Perrin Aybara wrote: hi.. my code was working pretty well until yesterday.suddenly it started giving me bind error: address already in use. but i have logged out and again logged in, but still the problem is not solved can somebody give me solution for this thankx perrin Next time, please ask a slightly smarter question: www.catb.org/~esr/faqs/smart-questions.html I presume you are talking about a socket-based server program? There's a timeout period during which your server port will be left unusable (according to the TCP standards). You can avoid this by setting the socket.SO_REUSEADDR option when you open your server socket. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
script to automate GUI application (newbie)
Dear Python experts, I have a GUI application (Windows; apparently written in Java) which I want to use through a script (without a mouse or keyboard). First, one of several buttons needs to be clicked (no keyboard shortcuts available, but I can measure the coordinates in pixels from the top left corner of the window to the center of the button to be clicked). Then, a window with a few drop-down lists pops up - I have to make some choices and click OK (it's possible to navigate from one drop-down to the next with Tab, and hit Enter for OK). I want to run the script above from code (if this then click ... and OK) and perhaps by means of several desktop shortcuts (one shortcut for each set of GUI inputs). Is such a script possible? If yes, how do I get there? I searched comp.lang.python but didn't find something directly applicable (or so it seemed to me - I'm a beginner). Directions (and sample code, if possible) will be warmly appreciated. Thank you, b. __ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250 -- http://mail.python.org/mailman/listinfo/python-list
Re: Integration with java (Jpype vs. JPE)
Steve Menard wrote: To asnwer your question more fully, the jpype-specific cide is only for looking up the Classes and startting/stopping the environment. For everything else, Java objects and classes are used as regular Python objects. Thanks for the response. Currently I don't need to use java but in the past when I explored such a possibility I looked at jpype and I was unable to understand from the documentation what it actually does. There is a lot of text there, but it is all concerning catching errors or other subtleties. For a new visitor the most important question is about how it works, what does it do, and how can it be applied for the given problem. everything else, Java objects and classes are used as regular Python objects. This is too generic. My question was a little more specific, how would I pass a python list as an argument of a java class/method or transform a java list into a python one? You don't have to answer it here, I'm just pointing out the kind of questions that I was unable to get an answer for on the jpype website. best, Istvan. -- http://mail.python.org/mailman/listinfo/python-list
Re: bind error!!!!!
Perrin Aybara wrote: my code was working pretty well until yesterday.suddenly it started giving me bind error: address already in use. google has the details: http://hea-www.harvard.edu/~fine/Tech/addrinuse.html but i have logged out and again logged in, but still the problem is not solved can somebody give me solution for this and you're sure that nobody else on this computer is running a process that's using the same port? on most platforms, you can use netstat to list all active connections and ports. /F -- http://mail.python.org/mailman/listinfo/python-list
RE: script to automate GUI application (newbie)
[bogdan romocea] | I have a GUI application (Windows; apparently written in Java) which I | want to use through a script (without a mouse or keyboard). First, one | of several buttons needs to be clicked (no keyboard shortcuts | available, but I can measure the coordinates in pixels from the top | left corner of the window to the center of the button to be clicked). | Then, a window with a few drop-down lists pops up - I have to | make some | choices and click OK (it's possible to navigate from one drop-down to | the next with Tab, and hit Enter for OK). | | I want to run the script above from code (if this then click ... and | OK) and perhaps by means of several desktop shortcuts (one shortcut | for each set of GUI inputs). | | Is such a script possible? If yes, how do I get there? I searched | comp.lang.python but didn't find something directly applicable (or so | it seemed to me - I'm a beginner). Directions (and sample code, if | possible) will be warmly appreciated. Have a look at WATSUP. I think it's the kind of thing you're after. http://www.tizmoi.net/watsup/intro.html TJG This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk -- http://mail.python.org/mailman/listinfo/python-list
Re: how to find site-packages path
Michael Hoffman wrote: Philippe C. Martin wrote: I am using my own install script for my software and am looking for a flawless way to figure out where python, and more specifically site-packages is installed. The flawless way would be to use distutils. In fact you shouldn't even need your own install script--it should do most of the work for you. can distutils install in any directory? for example, an application which has its own modules should be completely isolated from the general Python module namespace. how would you make distutils install in a completely separate directory hierarchy and not touch any of the site-packages directories or files? it looked like that was impossible from the documentation which is why I wrote my own installer. ---eric -- http://mail.python.org/mailman/listinfo/python-list
Re: Integration with java (Jpype vs. JPE)
Thanks for the info. I understand now the background and possibilities, but would like to refine my query: As I see it, writing a hybrid Java/Python application faces approximately three possibilities: (i) write the core in Java and do some scripting with Jython, (ii) write independent code in Java and in Python, and integrate using JPype (or similar), using Python also as a glue layer, (iii) write independent code in Java and in Python, and integrate using a neutral technology. Since much of the code in my project is already written, I am considering options ii and iii. This is how I perceive the work required in each case: Option ii would enable writing independent packages in Python and Java, and will require a glue layer in Python consisting of general administration and wrappers around Java packages written using JPype. I don't yet have a clear perception of how difficult it would be to make such wrappers, or to put my faith in JPype at this stage. Option iii would also enable writing independent packages in Python and Java, but its glue layer will be distributed between Python and Java using Jython and Pyro (I chose Pyro because it works in both CPython and Jython, and can be used to communicate between them). This would (to the best of my understanding) enable a smoother interface between Java and Python, but will probably complicate somewhat the glue layer, both because it would use networking to communicate, and because it would probably involve taking special measures to overcome the differences between CPython and Jython (since the glue layer will need to run on both of them). Joe. --- Cameron Laird [EMAIL PROTECTED] wrote: In article [EMAIL PROTECTED], Jon Perez [EMAIL PROTECTED] wrote: Can someone summarize in a nutshell what is the difference between JPype and JPE? JPE's the original. It provided more functionality than JPype has achieved so far, I believe (though that could change any day). I think no one now maintains JPE. Someone really ought to include a couple of sentences to that effect on the front page of URL: http://jpype.sf.net/ . -- http://mail.python.org/mailman/listinfo/python-list __ Do you Yahoo!? The all-new My Yahoo! - What will yours do? http://my.yahoo.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Advice to a Junior in High School?
collegebabe2004 wrote: I would suggest taking Japanese because you will have to work with them eventually if you do decide to choose compsci as your proffesion. Over what time frame should I expect this requirement to become critical? I'd like to know so I can reserve a spot in the next Japanese course in the area, if you think it's really urgent. Also, should I plan on adopting various aspects of the Japanese culture as well, or will a mastery of the language be sufficient? -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: MemoryError with parser.suite and wrong encoding declaration
On Tue, 18 Jan 2005 16:16:32 +0100, Thomas Heller wrote:
Sylvain Thenault [EMAIL PROTECTED] writes:
Hi there !
I've noticed the following problem with python = 2.3 (actually 2.3.4
and 2.4):
[EMAIL PROTECTED]:test$ python
Python 2.3.4 (#2, Sep 24 2004, 08:39:09) [GCC 3.3.4 (Debian 1:3.3.4-12)]
on linux2 Type help, copyright, credits or license for more
information.
import parser
parser.suite('# -*- coding: IBO-8859-1 -*-')
Traceback (most recent call last):
File stdin, line 1, in ?
MemoryError
parser.suite('# -*- coding: ISO-8859-1 -*-')
parser.st object at 0xb7e5e060
Shouldn't parser.suite just ignore the wrong encoding declaration, or at
least raise a more appropriate exception. IMHO the first solution would
be better, since that's the behaviour of the (C) python interpreter.
Ignore the wrong declaration? All Python's that I have (on windows, at
least) raise a SyntaxError:
File x.py, line 1
SyntaxError: 'unknown encoding: IBO-8859-1'
hum, right (with python = 2.3 which is the first release using those
declaration...). I was sure to have checked this but I've obviously
missed something. Maybe the fact that being able to parse it anyway is
the solution I wish has driven me to write this ;) I would like this
behaviour so that pylint can check a module with a wrong encoding
declaration anyway. But at least, SyntaxError would be better than
MemoryError.
See also:
http://www.python.org/sf/979739
thanks
--
Sylvain Thénault LOGILAB, Paris (France).
http://www.logilab.com http://www.logilab.fr http://www.logilab.org
--
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Re: script to automate GUI application (newbie)
Bogdan, If your app is written in Java, take a look at Marathon (http://marathonman.sourceforge.net/). It uses Jython as its scripting language and it's pretty smart about how it does automation (i.e. it doesn't look at screen coordinates, but at control names). It also offers a capture/replay functionality, and it automatically builds the Jython script that drives your flow of actions. You can then edit and enhance the script manually. Grig bogdan romocea wrote: Dear Python experts, I have a GUI application (Windows; apparently written in Java) which I want to use through a script (without a mouse or keyboard). First, one of several buttons needs to be clicked (no keyboard shortcuts available, but I can measure the coordinates in pixels from the top left corner of the window to the center of the button to be clicked). Then, a window with a few drop-down lists pops up - I have to make some choices and click OK (it's possible to navigate from one drop-down to the next with Tab, and hit Enter for OK). I want to run the script above from code (if this then click ... and OK) and perhaps by means of several desktop shortcuts (one shortcut for each set of GUI inputs). Is such a script possible? If yes, how do I get there? I searched comp.lang.python but didn't find something directly applicable (or so it seemed to me - I'm a beginner). Directions (and sample code, if possible) will be warmly appreciated. Thank you, b. __ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250 -- http://mail.python.org/mailman/listinfo/python-list
simultaneous multiple requests to very simple database
I have an application where I need a very simple database, effectively a very large dictionary. The very large dictionary must be accessed from multiple processes simultaneously. I need to be able to lock records within the very large dictionary when records are written to. Estimated number of records will be in the ballpark of 50,000 to 100,000 in his early phase and 10 times that in the future. Each record will run about 100 to 150 bytes. speed is not a huge concern although I must complete processing in less than 90 seconds. The longer the delay however the greater number of processes must be running parallel in order to keep the throughput up. It's the usual trade-off we have all come to know and love. it is not necessary for the dictionary to persist beyond the life of the parent process although I have another project coming up in which this would be a good idea. at this point, I know they will be some kind souls suggesting various SQL solutions. While I appreciate the idea, unfortunately I do not have time to puzzle out yet another component. Someday I will figure it out because I really liked what I see with SQL lite but unfortunately, today is not that day (unless they will give me their work, home and cell phone numbers so I can call when I am stuck. ;-) So the solutions that come to mind are some form of dictionary in shared memory with locking semaphore scoreboard or a multithreaded process containing a single database (Python native dictionary, metakit, gdbm??) and have all of my processes speak to it using xmlrpc which leaves me with the question of how to make a multithreaded server using stock xmlrpc. so feedback and pointers to information would be most welcome. I'm still exploring the idea so I am open to any and all suggestions (except maybe SQL :-) ---eric -- http://mail.python.org/mailman/listinfo/python-list
Re: Advice to a Junior in High School? [OT]
On Tue, 18 Jan 2005 11:04:01 -0500, rumours say that Peter Hansen [EMAIL PROTECTED] might have written: collegebabe2004 wrote: I would suggest taking Japanese because you will have to work with them eventually if you do decide to choose compsci as your proffesion. [Peter] Over what time frame should I expect this requirement to become critical? I'd like to know so I can reserve a spot in the next Japanese course in the area, if you think it's really urgent. Also, should I plan on adopting various aspects of the Japanese culture as well, or will a mastery of the language be sufficient? I think having a katana next to your keyboard will suffice to give the *impression* you have mastered enough of the japanese culture, Peter :) -- TZOTZIOY, I speak England very best. Be strict when sending and tolerant when receiving. (from RFC1958) I really should keep that in mind when talking with people, actually... -- http://mail.python.org/mailman/listinfo/python-list
makepy crashing
Has anyone sucessfully run makepy and Microsoft Word Object Library (9.0)? Mine crashes under XP Pro and Python 2.4. It only seems to be word that has the problem, though. I get a dialog that says that pythonwin.exe has crashed: AppName: pythonwin.exe AppVer: 0.0.0.0 ModName: ntdll.dll ModVer: 5.1.2600.1217Offset: 96f9 -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050118 keyed list
Also sprach Jürgen Exner:
Xah Lee wrote:
© %a = ('john',3, 'mary', 4, 'jane', 5, 'vicky',7);
© use Data::Dumper qw(Dumper);
© print Dumper \%a;
Wow, my compliments. The very first time that using Data::Dumper actually
may do something useful (formats the data more nicely). Still, why you are
passing a reference is beyond me.
How else would you use 'Dumper' on a hash?
Tassilo
--
$_=q#,}])!JAPH!qq(tsuJ[{@tnirp}3..0}_$;//::niam/s~=)]3[))_$-3(rellac(=_$({
pam{rekcahbus})(rekcah{lrePbus})(lreP{rehtonabus})!JAPH!qq(rehtona{tsuJbus#;
$_=reverse,s+(?=sub).+q#q!'qq.\t$.'!#+sexisexiixesixeseg;y~\n~~;eval
--
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RE: simultaneous multiple requests to very simple database
Eric S. Johansson wrote: I have an application where I need a very simple database, effectively a very large dictionary. The very large dictionary must be accessed from multiple processes simultaneously. I need to be able to lock records within the very large dictionary when records are written to. Just to clarify, you want shared-read until a write, at which point you want to lock just the item being written? Or would page or table locking be acceptable at that point? Robert Brewer MIS Amor Ministries [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
One-Shot Property?
I have many cases in my code where I use a property for calculating a value on-demand. Quite a few of these only need to be called once. After that the value is always the same. In these properties, I set a variable in the instance as a cached value and return that value on subsequent calls. It would be nice if there was a descriptor that would do this automatically. Actually, what would be really nice is if I could replace the property altogether and put the calculated value in its place after the first call, but the property itself prevents me from doing that. Is this possible? -- Kevin Smith [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050118 keyed list
Jay Tilton wrote: : # the syntax of keyed list in Perl is too complex : # to be covered in a short message. JFTR: keyed lists are called dictionaries in Python. [1]Message-ID: [EMAIL PROTECTED] This guy's wish-wash is starting to be funny, after all! Reinhold -- http://mail.python.org/mailman/listinfo/python-list
Tkinter in thread hangs on windows but not on Linux
Hi,
I need to pop-up in a modless manner some windows from an existing
Tkinter loop. The following code works OK under Linux: the second window
opens, shows the information, and quits cleanly when destroyed. However,
under windows, I get the second window without the content (so I hang in
run I guess), and both the thread and the calling process hang.
Any clue ?
Thanks
Philippe
#***
class SC_DOCS(threading.Thread):
__m_smg = None
__m_title = None
def __init__(self,p_msg,p_title):
threading.Thread.__init__(self)
self.__m_msg = p_msg
self.__m_title = p_title
#***
def run (self):
l_r = Tk()
l_r.title(self.__m_title)
l_f = Frame(l_r)
l_f.pack(side=TOP, expand=YES, fill=BOTH)
l_st = ScrolledText(l_f)
l_st.pack(side=TOP, expand=YES, fill=BOTH)
l_st.insert(END,self.__m_msg)
l_r.mainloop()
.
.
.
l_d = SC_DOCS('A MESSAGE', 'A TITLE')
l_d.start()
.
.
.
--
***
Philippe C. Martin
SnakeCard LLC
www.snakecard.com
***
--
http://mail.python.org/mailman/listinfo/python-list
Re: [perl-python] 20050118 keyed list
Jürgen Exner wrote: © # see perldoc perldata for an unix-styled course. Excuse me? Do you mind explaining where exactly perldata is Unix-styled? Remember: Perl == Unix == Satan. Reinhold -- http://mail.python.org/mailman/listinfo/python-list
Re: simultaneous multiple requests to very simple database
Robert Brewer wrote: Eric S. Johansson wrote: I have an application where I need a very simple database, effectively a very large dictionary. The very large dictionary must be accessed from multiple processes simultaneously. I need to be able to lock records within the very large dictionary when records are written to. Just to clarify, you want shared-read until a write, at which point you want to lock just the item being written? Or would page or table locking be acceptable at that point? just the item/record. I'm doing arrival rate calculations. each record contains a set of arrival times and I am rewriting the record every time a new entry arrives. complete page or table locking will work in the sense that it will prevent collisions but it will have an increasing impact as load and simultaneous table but not record accesses increase. ---eric -- http://mail.python.org/mailman/listinfo/python-list
Re: One-Shot Property?
Kevin Smith wrote: I have many cases in my code where I use a property for calculating a value on-demand. Quite a few of these only need to be called once. After that the value is always the same. In these properties, I set a variable in the instance as a cached value and return that value on subsequent calls. It would be nice if there was a descriptor that would do this automatically. Actually, what would be really nice is if I could replace the property altogether and put the calculated value in its place after the first call, but the property itself prevents me from doing that. Is this possible? I was going to recommend taking a look at the memoize example on the Python wiki, but it seems to be missing at the moment. In any case, here's the URL: http://www.python.org/moin/PythonDecoratorLibrary There are also a few examples on the Cookbook, like this one: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/325205 It shouldn't be too difficult to adapt this technique so that it can be used to create properties. I wouldn't bother replacing the property with an attribute unless you have a specific reason to do so (performance, perhaps). HTH, Dave -- http://mail.python.org/mailman/listinfo/python-list
Re: script to automate GUI application (newbie)
It sounds like a case for the Expect program, to me. Try Google-ing for Expect. If you are looking for a Python approach, then try googling for Expect Python. Jim -- http://mail.python.org/mailman/listinfo/python-list
Re: One-Shot Property?
Kevin Smith wrote: I have many cases in my code where I use a property for calculating a value on-demand. Quite a few of these only need to be called once. After that the value is always the same. In these properties, I set a variable in the instance as a cached value and return that value on subsequent calls. It would be nice if there was a descriptor that would do this automatically. Actually, what would be really nice is if I could replace the property altogether and put the calculated value in its place after the first call, but the property itself prevents me from doing that. Is this possible? If you use the old-fashioned __getattr__ method instead of properties. __getattr__ gets called only if the value can't be found in the instance dictionary. def __getattr__ (self, attrname): try: method = getattr (self, 'calculate_' + attrname) except AttributeError: raise AttributeError, attrname value = method () setattr (self, attrname, value) return value And probably also through metaclasses. And decorators. Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: generator expressions: performance anomaly?
On Tue, 18 Jan 2005 14:05:15 +, Antoon Pardon wrote: I don't see how generating byte code for a = 9; when seeing the expression a = 3 + 6, would be a problem for non-functional languages. To answer nearly every post you've made to this thread, because Python doesn't have the resources to program to special cases. And as is often the case in this sort of discussion, sure, adding this might be only a little work, but there's thousands of enhancements of the same general work level and performance gain. So remember you're not just espousing this particular enhancement, you're implicitly arguing for the entire class (because there is nothing to discriminate in the argument this is fairly easy between this particular feature on your mind today and the other thousands of such features). To address your point more specifically, you can do this subexpression elimination to the extent that your expression is a purely functional one. a = 3 + 6, while written in an imperative language and setting a variable in an imperative manner, has a functional subexpression 3 + 6, that has no side-effects, etc., so the compiler could reduce it if it knew how. (In Python, that's a function call, but since you can't change __add__ on ints, you could do this, although there's still some special casing you're doing that will ripple unpleasantly through the code.) But as soon as you call any sort of method or function, you're done. Ultimately, the use is fairly limited; I can't imagine the execution time saved would reach the time of implementation for weeks after a release, even aggregating across all Python use in the world, and real time gained (i.e., time useful to a human) would probably never add up to the implementation time. So why bother? That's a horrid trade off when there are so many other real gains to be had. -- http://mail.python.org/mailman/listinfo/python-list
Re: ANNOUNCE: Altova ... blah blah blah
Altova Announcements wrote: Altova Unveils . [spam] Well now, I didn't like their products very much already, but this spam has certainly made them drop another few steps down on my scale. Hmpf. --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: One-Shot Property?
Kevin Smith wrote:
I have many cases in my code where I use a property for calculating a
value on-demand. Quite a few of these only need to be called once.
After that the value is always the same. In these properties, I set a
variable in the instance as a cached value and return that value on
subsequent calls. It would be nice if there was a descriptor that would
do this automatically. Actually, what would be really nice is if I
could replace the property altogether and put the calculated value in
its place after the first call, but the property itself prevents me from
doing that.
This should do it:
class CachingProperty(object):
def __init__(self, attr_name, calculate_function):
self._name = attr_name
self._calculate = calculate_function
def __get__(self, obj, type=None):
if obj is None:
return self
else:
value = self._calculate(obj)
setattr(obj, self._name, value)
return value
And example code:
class Foo(object):
... def calculate_value(self):
... print 'Calculating...'
... return 42
... foo = CachingProperty('foo', calculate_value)
...
bar = Foo()
bar.__dict__
{}
bar.foo
Calculating...
42
bar.foo # Notice that the print statement doesn't run this time
42
bar.__dict__
{'foo': 42}
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Re: Integration with java (Jpype vs. JPE)
Joachim Boomberschloss wrote: Option iii would also enable writing independent packages in Python and Java, but its glue layer will be distributed between Python and Java using Jython and Pyro (I chose Pyro because it works in both CPython and Jython, and can be used to communicate between them). Please note that currently it is not possible to use Pyro as a server in Jython. Only as a client. Also; last time I checked there were some bugs in the Jython compiler that were triggered by Pyro's code (parts of it would give a compile error). See http://www.razorvine.net/python/PyroAndJython --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Print to Windows default Printer
I am new to Python and I am having considerable trouble trying to print (using a simple script) to the default printer rather than the screen. Thanks for any help. S -- http://mail.python.org/mailman/listinfo/python-list
Re: Print to Windows default Printer
Samantha wrote: I am new to Python and I am having considerable trouble trying to print (using a simple script) to the default printer rather than the screen. Thanks for any help. Please show some example code, and explain in more detail what you are trying to do. There are perhaps *dozens* of different ways to do printing under Windows, and we can't guess which approach you are trying, nor which might be suitable for your needs. -Peter -- http://mail.python.org/mailman/listinfo/python-list
pickling extension class
Hi all, I have a problem pickling an extension class. As written in the Extending/Embedding Manual, I provided a function __reduce__ that returns the appropreate tuple. This seams to work fine, but I still cannot pickle because of the following error: from model import hyper g = hyper.PeriodicGrid(4,4,1) g.__reduce__() (type 'hyper.PeriodicGrid',(4.,4.,1.)) import pickle pickle.dump(g,file(test,w)) Traceback (most recent call last): File pickle_test.py, line 5, in ? pickle.dump(g,file(test,w)) File /sw/lib/python2.4/pickle.py, line 1382, in dump Pickler(file, protocol, bin).dump(obj) File /sw/lib/python2.4/pickle.py, line 231, in dump self.save(obj) File /sw/lib/python2.4/pickle.py, line 338, in save self.save_reduce(obj=obj, *rv) File /sw/lib/python2.4/pickle.py, line 414, in save_reduce save(func) File /sw/lib/python2.4/pickle.py, line 293, in save f(self, obj) # Call unbound method with explicit self File /sw/lib/python2.4/pickle.py, line 760, in save_global raise PicklingError( pickle.PicklingError: Can't pickle type 'hyper.PeriodicGrid': it's not found as hyper.PeriodicGrid dir(hyper) ['Dir', 'Neighbors', 'PeriodicGrid', 'PeriodicPos', '__doc__', '__file__', '__name__', 'refcount'] hyper.PeriodicGrid type 'hyper.PeriodicGrid' So pickle complains about the class PeriodicGrid not being found in the module hyper, but a dir() proves that python can find it. Has anyone an idea what's going wrong here? Any help appreceated, - harold - -- What is mind? -- Doesn't matter. What is matter? -- Never mind! -- -- http://mail.python.org/mailman/listinfo/python-list
Re: hex notation funtion
tertius wrote: Hi, Is there a builtin function that will enable me to display the hex notation of a given binary string? (example below) Does this help: hello.encode(hex) '68656c6c6f' deadbeef.decode(hex) '\xde\xad\xbe\xef' ? --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: hex notation funtion
Would that do it? for i in my_byte_string: = atoi(binascii.hexlify(i),16) Regards, Philippe On Tue, 18 Jan 2005 20:43:44 +0200, tertius wrote: Hi, Is there a builtin function that will enable me to display the hex notation of a given binary string? (example below) many thanks Tertius () 02 11 00 00 46 5A 1A 82 02 11 00 39 36 39 33 39 FZ.96939 0016(0010) 36 39 33 00 0A 30 33 37 34 34 39 35 38 25 DD 01 693..03744958%.. -- http://mail.python.org/mailman/listinfo/python-list
Re: Print to Windows default Printer
Thanks for he quick response. This is small sample code from a PSP script to get Exit Info of a digital image. I want to print to the printer rather than the screen. --- Info = App.Do( Environment, 'ReturnImageInfo' ) print print 'Input Device Information' for key in InputDeviceKeys: if OnlyExistingData == 0 or Info[key] != '': print key, ': ', Info[key] print print 'Artist Information' for key in ArtistKeys: if OnlyExistingData == 0 or Info[key] != '': print key, ': ', Info[key] print -- Is there an easy way to do it. Right now I copy and paste to a txt file then print the file? S Peter Hansen [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Samantha wrote: I am new to Python and I am having considerable trouble trying to print (using a simple script) to the default printer rather than the screen. Thanks for any help. Please show some example code, and explain in more detail what you are trying to do. There are perhaps *dozens* of different ways to do printing under Windows, and we can't guess which approach you are trying, nor which might be suitable for your needs. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: how to find site-packages path (Michael Hoffman) - use distutils
Philippe C. Martin wrote: Why would you want to copy any *.pyc instead of compiling them on site? I know that sounds terrible to the open source community, but I do not intend to release the source code for my product That's not why I asked. I'll leave the politics up to you. The thing is, that the path info gets cached in the *.pyc file. This may lead to confusing tracebacks - might they occur - when the user does not install to the exact same drive/path as you did. Additionally: if you *do* want to distribute *.pyc only, I personally wouldn't find it terribly neat if you stuck those into the site-packages directory of my Python installation. I - for one - would want to know what kind of source code you place along *my* sys.path. Maybe you should consider using py2exe to distribute - keeping your *.pyc out of the user's Python directory tree, if any, entirely. Also, you may want to consider using Inno Setup as deployment tool (if Windows is your target platform). Using distutils for a *.py-less installer seems pretty pointless. Regards, -- Vincent Wehren - pls go to philippecmartin.com/applications.html for my _small_ contributions :-)) Regards, Philippe -- http://mail.python.org/mailman/listinfo/python-list
Re: how to find site-packages path (Michael Hoffman) - use distutils
I actually target Unix and windows so pyexe won't cut it I'm afraid - same issue with Inno. As far as the site-package target, I don't fully understand your relunctancy. Just as my potential users might not own a compiler, they might not be computer proficient enough to easily understand how to change the sys.path. So until I have found a clean cross platform solution I'm going to have to stick to site-packages. Best regards, Philippe -- *** Philippe C. Martin SnakeCard LLC www.snakecard.com *** -- http://mail.python.org/mailman/listinfo/python-list
Re: How to prevent the script from stopping before it should
Fredrik Lundh wrote: Steve Holden wrote: You will need to import the socket module and then call socket.setdefaulttimeout() to ensure that communication with non-responsive servers results in a socket exception that you can trap. or you can use asynchronous sockets, so your program can keep processing the sites that do respond at once while it's waiting for the ones that don't. for one way to do that, see Using HTTP to Download Files here: http://effbot.org/zone/effnews-1.htm (make sure you read the second and third article as well) Dear Fredrik Lundh, Thank you for the link. I checked it. But I have not found an answer to my question. My problem is that I can not finish( sometimes) to download all pages. Sometimes my script freezes and I can not do nothing but restart the script from the last successfully downloaded web page. There is no error saying that was an error. I do not know why; maybe the server is programed to reduce the numbers of connection or there maybe different reasons.So, my idea was two threads. One master ,suprevising the slave thread that would do downloading and if the slave thread stopped, master thread would start another slave. Is it a good solution? Or is there a better solution? Thanks for help Lad -- http://mail.python.org/mailman/listinfo/python-list
Re: hex notation funtion
This will do it:
int('1000', 2)
128
hex(int('1000', 2))
'0x80'
--
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Re: hex notation funtion
On 2005-01-18, tertius [EMAIL PROTECTED] wrote:
Is there a builtin function that will enable me to display the hex
notation of a given binary string? (example below)
' '.join('%02x' % ord(b) for b in s)
--
Grant Edwards grante Yow! This is a NO-FRILLS
at flight -- hold th' CANADIAN
visi.comBACON!!
--
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Re: pickling extension class
harold fellermann [EMAIL PROTECTED] wrote: File /sw/lib/python2.4/pickle.py, line 760, in save_global raise PicklingError( pickle.PicklingError: Can't pickle type 'hyper.PeriodicGrid': it's not found as hyper.PeriodicGrid dir(hyper) ['Dir', 'Neighbors', 'PeriodicGrid', 'PeriodicPos', '__doc__', '__file__', '__name__', 'refcount'] hyper.PeriodicGrid type 'hyper.PeriodicGrid' So pickle complains about the class PeriodicGrid not being found in the module hyper, but a dir() proves that python can find it. Has anyone an idea what's going wrong here? These symptomps are pretty weird -- let's try to pin things down a bit more. The relevant few lines of pickle.py are: try: __import__(module) mod = sys.modules[module] klass = getattr(mod, name) except (ImportError, KeyError, AttributeError): raise PicklingError( so, could you please edit your pickle.py to provide VASTLY more info, say: try: print 'Here it goes...:' _xx = __import__(module) print ' __import__ says: %r' % (_xx,) mod = sys.modules[module] print ' in sys.modules: %r' % (mod,) klass = getattr(mod, name) print ' klass is: %r' % (klass,) except (ImportError, KeyError, AttributeError), _xx: print ' OOPS, error (%s): %s' % (_xx.__class__, _xx) raise PicklingError( and let us know exactly what his modified pickle.py outputs...? Thanks, Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: pickling extension class
On 18.01.2005, at 20:31, Alex Martelli wrote:
harold fellermann [EMAIL PROTECTED] wrote:
File /sw/lib/python2.4/pickle.py, line 760, in save_global
raise PicklingError(
pickle.PicklingError: Can't pickle type 'hyper.PeriodicGrid': it's
not found as hyper.PeriodicGrid
dir(hyper)
['Dir', 'Neighbors', 'PeriodicGrid', 'PeriodicPos', '__doc__',
'__file__', '__name__', 'refcount']
hyper.PeriodicGrid
type 'hyper.PeriodicGrid'
So pickle complains about the class PeriodicGrid not being found in
the
module hyper, but a dir()
proves that python can find it. Has anyone an idea what's going wrong
here?
These symptomps are pretty weird -- let's try to pin things down a bit
more. The relevant few lines of pickle.py are:
try:
__import__(module)
mod = sys.modules[module]
klass = getattr(mod, name)
except (ImportError, KeyError, AttributeError):
raise PicklingError(
so, could you please edit your pickle.py to provide VASTLY more info,
[...]
and let us know exactly what his modified pickle.py outputs...?
Here it goes...:
OOPS, error (exceptions.ImportError): No module named hyper
Traceback (most recent call last):
File pickle_test.py, line 5, in ?
pickle.dump(g,file(test,w))
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 1387,
in dump
Pickler(file, protocol, bin).dump(obj)
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 231,
in dump
self.save(obj)
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 338,
in save
self.save_reduce(obj=obj, *rv)
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 414,
in save_reduce
save(func)
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 293,
in save
f(self, obj) # Call unbound method with explicit self
File /Volumes/space/Users/harold/uni/pace/ono/pickle.py, line 765,
in save_global
raise PicklingError(
pickle.PicklingError: Can't pickle type 'hyper.PeriodicGrid': it's
not found as hyper.PeriodicGrid
I have noticed that the error does not occur, when the imported module
('hyper') is in the same directory as the script that pickles. When it
is imported from a subpackage (like in the code
I sent you) it goes wrong.
- harold -
--
Reality is for people who lack imagination.
--
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Re: hex notation funtion
On 2005-01-18, Grant Edwards [EMAIL PROTECTED] wrote:
On 2005-01-18, tertius [EMAIL PROTECTED] wrote:
Is there a builtin function that will enable me to display the hex
notation of a given binary string? (example below)
' '.join('%02x' % ord(b) for b in s)
Oops. Should be:
' '.join(['%02x' % ord(b) for b in s])
--
Grant Edwards grante Yow! .. Am I in a SOAP
at OPERA??
visi.com
--
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Re: Fuzzy matching of postal addresses
I think you guys are missing the point. All you would need to add to get a 'probable match' is add another search that goes through the 10% that didnt get matched and do a endswith search on the data. From the example data you showed me, that would match a good 90% of the 10%, leaving you with a 1% that must be hand matched. You would have to combine this idea with Jeff Shannon's idea to make it work more efficiently. -- http://mail.python.org/mailman/listinfo/python-list
