[wxPython-users] a couple of scary moments in wxpython under win32 under py2exe with a ridiculous deadline thrown in...

[Brian Martin]

Thanks for the typical mailing list punch-in-the-face.

On 8/14/07, Chris Mellon <arkanes at gmail.com> wrote:
>
> On 8/14/07, Brian Martin <thebrianmartin at gmail.com> wrote:
> > Just some weird things that happened during my project that I wanted to
> > share....
> >
> > 1) For simplicity sake (and because my installer knowledge was minimal),
> > I was just putting icons and logos for my application in the root
> directory
> > of the source folder. When I would refer
> > to them when creating an image for example i could just exclude any path
> > information (ie. 'foo.img' vs 'c:\Program Files\proj\foo.img')   and
> > wxpython (or python) would know how to get them. Then, when adding a
> feature
> > to allow someone to add a custom graphic to the application I make a
> call to
> > shutil.copy to move the image from a user location into the source tree.
> As
> > soon as I do this, wxpython could not find any of my images or icons. I
> had
> > to explicitly point to them or it would barf. Now this is probably the
> best
> > way to do it and I just made a global constant which used sys.path[0].
> > Regardless, it was interesting. Mid-application, references to these
> images
> > were broken when i called the shutil.copy command.
> >
>
> Your problem here is lack of knowledge. All common OSes have a concept
> known as the "current working directory". Relative paths are so called
> because they are relative to this directory.
>
> You probably used wx.FileDialog to allow the user to select the file
> to move. wx.FileDialog changes the current working directory, because
> windows is bizarre. Clear the wx.FD_CHANGE_DIR style flag to prevent
> this behavior.
>
> There's actually lots of different ways this can fail and you've run
> into only one of them. Because of this, relying on the current working
> directory to find your data files is heavily discouraged.
>
> > 2) This is related to #1 and was extremely stressful at the time. I
> packaged
> > this project up for my boss to take to a presentation using py2exe. The
> > killer here is that *while running under py2exe* the sys.path contains a
> > single entry which is the "library.zip" file. So my application was no
> > searching for the icons and images here: "C:\Program
> > Files\proj\library.zip\hello
> >  .gif"  where sys.path[0] contained: C:\Program
> > Files\proj\library.zip
> >
>
> sys.path isn't intended to be used to find your data files. It's a
> mechanism used by Python to find imports. wxPython, in the interests
> of platform compatability, provides the wx.StandardPaths class which
> can help you find well-defined file locations.
>
> > 3) Keyboard events between win32 and Linux are a not compatible. You
> cannot
> > depend on it working remotely the same if you, for example, spend part
> of an
> > evening in Ubuntu working on a project and then try it on XP the next
> > morning at work.
>
> You should always test on platforms that you are going to deploy on.
> There are some platform differences but by far a larger category of
> problems is incorrect code that happens to work on one platform
> failing on another. Giving details about your problem will help more
> than broad statements of incompatibility.





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