🌐 Mailman 3 March 2003 - Python-list - python.org

Trying to use boa-constructor
by Doug Farrell March 2, 2003

March 2, 2003

Hi all, I have a couple of questions. I'd like to use boa-constructor to build some GUI forms for a wxPython program we are working on at work. This would ease the problem of building forms by hand. Does anyone have any good tutorial information on using boa-constructor? I find the built in help not much help. :) Second, I'm having problem at home running Boa.py (the main entry point for the program. It tells me the global name "string" is not defined and bombs out. Any clues as to what is going on? I have python 2.2.1 running with the latest rpm file from wxPython. Thanks in advance, Doug Farrell

2 1

Formatting Traceback info in the Python/C API
by ngopalas＠yahoo.com March 1, 2003

March 1, 2003

Hi everyone, I have a question. I want to format and print traceback information using the C API. The reason I do not want to use PyErr_Print() is because on Windows I want to capture the text formatted traceback and put it up as a dialog box. I have looked over the entire C API but cannot find a way to do it. I want to do a if (PyErr_Occurred()) { PyObject *exception, *value, *traceback; PyErr_Fetch(&exception,&value,&traceback); /* Now I want to do something like what the traceback module does */ string = PyErr_FormatTraceback(traceback); GuiDisplay(string); } Any help would be appreciated. I thought of importing the traceback module in the C API and then do a PyCallObject(...) etc but that seems like a very roundabout way of doing things. Thanks, NG

2 1

XML - attributes query
by Newt March 1, 2003

March 1, 2003

Hi all, I'm trying to use the following code fragment tp pick up some attributes from an XML element. doc = xml.dom.minidom.parse("gard_skills_ele.xml") for s in doc.getElementsByTagName("skill"): print s.childNodes.length for c in s.childNodes: print "--> " + c.nodeName print "--> Has " + str(s.attributes.length) + " attributes" print str(s.attributes.getNamedItem("name")) The xml input file looks like: <xml> <skill name="Art" points="1" /> <skill name="Calligraphy" points="1" /> <skill name="Ettiquette" points="1" /> </xml> When I run the code, I get the following error: Traceback (most recent call last): File "D:\py_stuff\test_xml.py", line 22, in ? print str(s.attributes.getNamedItem("name")) AttributeError: NamedNodeMap instance has no attribute 'getNamedItem' The book I'm using (Python and XML) says that NamedNodeMap does support getNamedItem. Has anyone tried to use this? Newt

2 2

Re: My CTO is learning Python....
by laotseu March 1, 2003

March 1, 2003

Bjorn Pettersen wrote: > ....time to run screeming from the building <wink>. His problem, is that > "There doesn't seem to be any good books on Python". Pressed a little > more, it was refined to "either the documentation assumes you've never > programmed before, and spends volumes of text introducing loop > constructs etc." (that was the commentary on the Tutorial <sigh>), "or, > the author seems to be in love with the language purely for its advanced > and obscure features" (he'd hoped 'Thinking in Python' would be like the > C++/Java equivalent...). Pressed a little bit further, he commented: > "what I'm really looking for is a quick introduction for someone that > allready knows C++ or Java". > > So on the positive side, our CTO is voluntarily learning Python -- on > the other hand, every time I show him the pydiomatic way of doing > something, his eyes get really big and he comments "you can do that? Why > isn't that in the documentation?" Followed by me pointing out where in > the docs it is, followed by "well, that's not very obvious..." (snip) > What I've been looking for, and not found, is examples of how dynamic > typing and interface polymorphism make your code shorter, simpler, and > easier. I think this is the whole point : this guy has static typing habits and so he does thinks that way... Not being a C++ expert (thanks God, if He exists !-), it took me some time to realize the benefits of dynamic typing and how to use it. In fact, I had to start learning a bit of Lisp and Smalltalk to start thinking pythonic... I agree that some strength of Python may not be obvious for static-languages-folks reading the doc. but-i'm-not-sure-this-will-help-you !-) Laotseu

2 1

Re: My CTO is learning Python....
by Nick Vargish March 1, 2003

March 1, 2003

Have you tried showing him the Cookbook, the printed version? That book induces lightbulbs over peoples' heads faster than any other Python resource I can think of. It's especially cool because it lets people learn "pydiomatic" approaches to problem domains they are especially interested in, without going through a lot of "this is a loop, this is a class" material. For example, If he's interested in XML, the XML chapter is excellent for demonstrating the power of Python's libraries and object oriented features. Nick -- #include<stdio.h> /* SigMask 0.3 (sig.c) 19990429 PUBLIC DOMAIN "Compile Me" */ int main(c,v)char *v;{return !c?putchar(*v-1)&&main(0,v+ /* Tweaks welcomed. */ 1):main(0,"Ojdl!Wbshjti!=obwAqbusjpu/ofu?\v\1");} /* build: cc -o sig sig.c */

2 1

Re: Hard to find bugs, misleading exceptions
by alex_nanou＠pochtamt.ru March 1, 2003

March 1, 2003

I think the most logical thing to do if you are told of a problem that seems not to exist, is to find exactly what the speaker suggests is the problem, *before* you start the debugger... (and you do have more than enough information to so here) in your case python suggests we find a tuple call... ")[\n\s]*([^)]*)" -- a typical regexp pattern to use. NOTE: the pattern above might differ slightly with different editors or libs.. (here written for vim) P.S. might be a good idea to write an automatic error output parser and code highlighter to do this job for us... (written in my ToDo list.. though I can't say when will I get to it ;) ) Best Regards...

1 0

RE: My CTO is learning Python....
by Bjorn Pettersen March 1, 2003

March 1, 2003

> From: laotseu [mailto:bdesth@removethis.free.fr] [...] > I think this is the whole point : this guy has static typing > habits and so he does thinks that way... Not being a C++ > expert (thanks God, if He exists !-), [...] Just in case you were wondering, I was in no way trying to say that anyone shouldn't program in C++. C++ excels in some areas where Python does not, so I think they're perfect complements to each other (and with Boost.Python they interoperate almost seamlessly). Of course, I've been programming in C++ for 14 years, so I'm probably not completely unbiased <grin>. -- bjorn

1 0

RE: My CTO is learning Python....
by Bjorn Pettersen March 1, 2003

March 1, 2003

> From: Nick Vargish [mailto:nav@adams.patriot.net] > > Have you tried showing him the Cookbook, the printed version? [...] Yup. Bought him a copy myself. It was "too clever", "not structured like a tutorial", and generally "not quite what I'm looking for" (*sigh*). I got half of those comments for the effbot's guide to the Standard Library also. Both of which I consider indispensable for any Pythonista... -- bjorn

1 0

RE: My CTO is learning Python....
by Bjorn Pettersen March 1, 2003

March 1, 2003

> From: Alex Martelli [mailto:aleax@aleax.it] > > Bjorn Pettersen wrote: > ... > > what I don't understand is why a bound method is special > > and can be used as a staticmethod, while regular functions > > (def/lambda) cannot? Anyone? > > ANY callable except a "regular function" can be "used as a > staticmethod" (and it can ONLY be used that way) -- because > looking up an attribute in a class's dictionary morphs > functions into methods (bound or unbound as appropriate), > but it morphs no other types of attribute whatsoever. [...] Thanks Alex! I can't even remember reading most of the stuff in 3.2 (RefMan)... guess what I'll be doing today :-) Btw., when is the Nutshell book coming out? I need more good books with proper attention to detail <wink>. -- bjorn

2 1

Re: Why does 2.3a2 change "slots" in complex?
by Greg Chapman March 1, 2003

March 1, 2003

On Fri, 28 Feb 2003 22:03:45 -0500, mertz(a)gnosis.cx (David Mertz) wrote: >One of the unit tests involves adding extra attributes to descendents of >standard data types. It turns out, that test breaks with Python 2.3a2, >because of a change in the implementation of complex. > >Here is a brief test case that shows the behavior. I am interested in >why this change was made. Is it a bug or a feature? If a feature, what >benefit does this have? If a bug... well, I guess that's the point of >an alpha version. If you check the type of c in your example, you'll find that it is complex under 2.3a2 (rather than __main__.Complex). I believe this is definitely a bug. It appears this problem was introduced by a change which causes the complex constructor (complex_new) to return its argument if it is of the exact type complex (rather than creating a new complex instance). Instead, I believe complex_new should also check to see if the type being constructed (i.e., the type parameter) is in fact exactly complex; if not, then it should try to create the new instance no matter what arguments it gets. I believe the correct fix would be to change this test: if (PyComplex_CheckExact(r) && i == NULL) to this: if (PyComplex_CheckExact(r) && i == NULL && PyComplex_CheckExact(type)) I'll file a bug report. --- Greg Chapman

1 1