🌐 Mailman 3 September 2006 - Python-list - python.org

Re: Python style: to check or not to check args and data members
by Joel Hedlund Sept. 3, 2006

Sept. 3, 2006

> Short answer: Use Traits. Don't invent your own mini-Traits. Thanks for a quick and informative answer! I'll be sure to read up on the subject. (And also: thanks Bruno for your contributions!) > Types are very frequently exactly the wrong thing you want to check for. I see what you mean. Allowing several data types may generate unwanted side effects (integer division when expecting real division, for example). I understand that Traits can do value checking which is superior to what I presented, and that they can help me move validation away from functional code, which is always desirable. But there is still the problem of setting an approprate level of validation. Should I validate data members only? This is quite easily done using Traits or some other technique and keeps validation bloat localized in the code. This is in line with the DRY principle and makes for smooth extensibility, but the tracebacks will be less useful. Or should I go the whole way and validate at every turn (all data members, every arg in every method, ...)? This makes for very secure code and very useful tracebacks, but does not feel very DRY to me... Are the benefits worth the costs? Do I build myself a fortress of unmaintainability this way? Will people laugh at my modules? Or taken to the other extreme: Should I simply duck-type everything, and only focus my validation efforts to external data (from users, external applications and other forces of evil). This solution makes for extremely clean code, but the thought of potential silent data corruption makes me more than a little queasy. What level do you go for? Thanks! /Joel Robert Kern wrote: > Joel Hedlund wrote: >> Hi! >> >> The question of type checking/enforcing has bothered me for a while, and >> since this newsgroup has a wealth of competence subscribed to it, I >> figured this would be a great way of learning from the experts. I feel >> there's a tradeoff between clear, easily readdable and extensible code >> on one side, and safe code providing early errors and useful tracebacks >> on the other. I want both! How do you guys do it? What's the pythonic >> way? Are there any docs that I should read? All pointers and opinions >> are appreciated! > > Short answer: Use Traits. Don't invent your own mini-Traits. > > (Disclosure: I work for Enthought.) > > http://code.enthought.com/traits/ > > Unfortunately, I think the standalone tarball on that page, uh, doesn't stand > alone right now. We're cleaning up the interdependencies over the next two > weeks. Right now, your best bet is to get the whole enthought package: > > http://code.enthought.com/ets/ > > Talk to us on enthought-dev if you need any help. > > https://mail.enthought.com/mailman/listinfo/enthought-dev > > > Now back to Traits itself: > > Traits does quite a bit more than "type-checking," and I think that is its > least-useful feature that it provides for Python users. Types are very > frequently exactly the wrong thing you want to check for. They allow inputs that > you would like to be invalid and disallow inputs that would have worked just > fine if you had relied on duck-typing. In general terms, Traits does > value-checking; it's just that some of the traits definitions check values by > validating their types. > > You have to be careful with type-checking, because it can introduce fragility > without enhancing safety. But sometimes you are working with other code that > necessarily has type requirements (like extension code), and moving the > requirements forward a bit helps build usable interfaces. > > Your examples would look like this with Traits: > > > from enthought.traits.api import HasTraits, Int, method > > class MyClass(HasTraits): > """My example class. > """ > > int_member = Int(0, desc="I am an integer") > > method(None, Int) > def process_data(self, data): > """Do some data processing. > """ > > self.int_member += 1 > > > a = MyClass(int_member=9) > a = MyClass(int_member='moo') > """ > Traceback (most recent call last): > File "<stdin>", line 1, in ? > File "/Users/kern/svn/enthought-lib/enthought/traits/trait_handlers.py", line > 172, in error > raise TraitError, ( object, name, self.info(), value ) > enthought.traits.trait_errors.TraitError: The 'int_member' trait of a MyClass > instance must be a value of type 'int', but a value of moo was specified. > """ > > # and similar errors for > # a.int_member = 'moo' > # a.process_data('moo') > > > The method() function predates 2.4 and has not yet been converted to a > decorator. We don't actually use it much. >

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regex matching rst code block?
by Edward K. Ream Sept. 3, 2006

Sept. 3, 2006

Here is a little regular expression puzzle. I wish a regex that matches an rst code block, that is, '::' followed by a group of lines all indented by at least as much as the first non-blank line following the '::' My guess is that this is not possible. Can anyone prove me wrong :-) Edward -------------------------------------------------------------------- Edward K. Ream email: edreamleo(a)charter.net Leo: http://webpages.charter.net/edreamleo/front.html --------------------------------------------------------------------

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Re: regex matching rst code block?
by Edward K. Ream Sept. 3, 2006

Sept. 3, 2006

> Why not convert the reStructuredText to XML and parse that? Because the problem arises for the jEdit syntax colorer whose most powerful pattern matcher is a regex. Edward -------------------------------------------------------------------- Edward K. Ream email: edreamleo(a)charter.net Leo: http://webpages.charter.net/edreamleo/front.html --------------------------------------------------------------------

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Re: Help with autotools
by pavel.starek＠gmail.com Sept. 3, 2006

Sept. 3, 2006

Jonh Wendell wrote: > Hi all! I need help with autotools stuff.. > > My directory structure: > > project_name > src > main.py > others.py > data > ui.glade > images.png > po > translations.po > > I'd like to do something like that: > > The files in "src" should be installed at: $prefix/lib/project_name > The files in "data" should be installed at: $prefix/share/project_name > > At $prefix/bin should be create a slink: > $prefix/bin/project_name -> $prefix/lib/project_name/main.py > > The listen (http://listengnome.free.fr/) does this, but it doesn't use > autotools... > > Can anyone help me? > I've tried a lot to make this work, but with no success... > > Thanks, > -- > Jonh Wendell Santana > Analista de Sistemas > > http://www.bani.com.br > MSN: jonhwendell(a)hotmail.com > GTalk/Jabber: jonh.wendell(a)gmail.com > Linux User #114432 Hi, in listen project Makefile is shown how to make this thing. URL for SVN view of Makefile for listen 0.4.3 is: http://svn.sourceforge.net/viewvc/listengnome/releases/0.4.x/0.4.3/Makefile… Cheers, Pavel

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pdf to hhp for boa-constructor help
by Eric_Dexter＠msn.com Sept. 3, 2006

Sept. 3, 2006

Is there a way to convert from .pdf to hhp so that I can add help files to boa constructor.. adding html to it would also be helpfull http://www.dexrow.com

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CONSTRUCT - Module Attributes and Execution Environment
by lazaridis_com Sept. 3, 2006

Sept. 3, 2006

I would like to change the construct: if __name__ == '__main__': to something like: if exec.isMain(): My (OO thought) is to place a class in an separate code module and to instantiate an singleton instance which would keep th something like this: class ExecutionEnv: def isMain(self) if CALLING_MODULE.__name__ == '__main__': return true else return false exec = ExecutionEnv() How to I get access to the CALLING_MODULE ? - Are ther alternative constructs/mechanism available, which could be used to add this functionality possiby directly to a code-module?

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Re: Pmw installation problem
by vedran_dekovic＠yahoo.com Sept. 3, 2006

Sept. 3, 2006

Fredrik Lundh je napisao/la: > vedran_dekovic(a)yahoo.com wrote: > > > When I download Pmw,and .py files copy to lib,then in python shell > > I write: > > where did you copy what files? you're supposed to place the *entire* > Pmw directory somewhere on your path (e.g. under site-packages). see > > http://pmw.sourceforge.net/doc/starting.html > > </F> All files (.py),I was copy in lib

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Python GUI/tk
by Ash.Shuklaa＠googlemail.com Sept. 3, 2006

Sept. 3, 2006

Hi, I am making a GUI with the help of python.In the program, when "ADD" button is pressed new frames build up and when you press "delete" button those frames will be destroyed . My problem is that these frames only get destroyed in Tk but the data structure associated with it (in Python) doesn't change. #!/usr/bin/python from Tkinter import* class Frame_1(LabelFrame): def __init__(self,master): LabelFrame.__init__(self,master) self.configure(text="Frame1") self.grid() def control_buttons(self,frame): Button( self, text = "Add", command = frame.add_button ).grid( ) Button( self, text = "Read", command = frame.read_button ).grid() class Frame_2(LabelFrame): def __init__(self,master): LabelFrame.__init__(self,master) self.configure(text ="Frame2") self.grid() self.sub_frame = [] def add_button(self): new_frame = Frame_2_1(self) # new_frame.grid() new_frame.populate() self.sub_frame.append(new_frame) # print self.sub_frame def read_button(self): print "#"*10 for sub_frame in self.sub_frame : print "-"*30 print "band:"+ sub_frame.band.get() print "channel:" + sub_frame.channel.get() class Frame_2_1(LabelFrame): def __init__(self,tkmaster): LabelFrame.__init__(self,tkmaster) self.configure(text ="DEFAULT") self.grid() def populate(self): self.band = StringVar() self.band.set("900") option = OptionMenu(self, self.band,"900","1800","1900" ).grid() self.channel = StringVar() self.channel.set("CS 1") option = OptionMenu(self,self.channel,"CS 1","CS 2","CS 3","CS 4").grid( ) global temp temp= temp+1 Button(self,text = "Remove"+ str(temp),command= self.delete_frame).grid() def delete_frame(self): self.destroy() root = Tk() temp=-1 # Create frame 1 frame_1 = Frame_1(root) # Create frame 2 frame_2 = Frame_2(root) frame_1.control_buttons(frame_2) root.mainloop() --------------------------------------------------------------------------

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Re: FYI: getting data from an OpenOffice.org spreadsheet
by alf Sept. 3, 2006

Sept. 3, 2006

Sybren Stuvel wrote: > Hi folks, > > Sometimes I have to feed data from an OpenOffice.org spreadsheet into > some Python program. To make that really easy, I've written a small > example program that connects to a running OpenOffice.org instance and > reads the data from the currently opened spreadsheet. > > Check out http://www.stuvel.eu/archive/28/ to see the source and > requirements. It took a lot of digging in the rather complex OOo API > documentation, but the end result is just as I like it: clean and > simple. I hope this helps people out! > > Sybren thx for sharing the experience. Do you know how to save a OO doc into M$ Excel format - I have a Python based server running on Linux box and need to produce Excel files. -- alf

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Re: Python-list Digest, Vol 36, Issue 33
by David J Birnbaum Sept. 3, 2006

Sept. 3, 2006

Dear John (cc python-list), >> You may find (1) that the file has formfeeds in >> it or (2) it has r"\f" in in it and you were mistaken about the >> interpretation or (3) something else. >> > ... > >> Thank you for the quick response. Ultimately I need to remap the "f" in >> "\f" to something else, so I worked around the problem by doing the >> remapping first, and I'm now getting the desired result. >> > > Please reply on-list. > > How could you read the file to remap an "f" if you were getting '\0x0C' > when you tried to read it? Are we to assume that it was case (2) i.e. > not a Python problem? > Possibly more than anyone else on-list cares to see, but it was case (3): I had misdiagnosed the input. The match was failing because I was reading the line improperly (when I remapped the "f" I was ... er ... inexplicably surprised when I couldn't find it, although it turned out to be there when I looked for the remapped value instead of for the original "f"). When I tried to troubleshoot it in an interpreter window, I misread the results, which is what prompted my inquiry on the list. Here's the intepreter diagnosis: >>> string1 = "blah \fR40\fC blah" >>> string1 'blah \x0cR40\x0cC blah' >>> string2 = "blah \\fR40\\fC blah" >>> string2 'blah \\fR40\\fC blah' If I create a file that consists of: <?xml version="1.0" encoding="UTF-8"?> <test> <line>Hi, there</line> <line>blah \fR40\fC blah</line> <line>Hi, there</line> </test> And then a python script that reads: import codecs import re file = open("test1.xml", "r") nePat = re.compile("\\\\f.") for line in file: print line print nePat.sub("TEST", line) the relevant line comes out as: <line>blah TEST40TEST blah</line> which is what I want. That is, the script was, indeed, reading the character string correctly, as you suggested, and the substitution that I ran into during my test in the interpreter window was a red herring. Thanks again for the advice to look more closely. Best, David

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