[wxpython-dev] Possible to derive from GC?

[Robin Dunn]

Nitro wrote:
> Hello,
> 
> I've send this message yesterday, but it seems it did not get through, 
> trying to sending it again.
> 
> 1) Is it possible to derive my own class from wx.GraphicsContext or 
> should I rather create a GC by itself and then delegate to it?

I expect that either would be ok, but past experience I would guess that 
the typical approach in this case would be delegation.


> 
> 2) wx.lib.pubsub seems to have a bug. If I change the code at line 860 
> class Foo2: to class Foo2(object): then the test breaks, because 
> _paramMinCount does not work anymore. Is there any reason to use if 
> tests in the _paramMinCount function? This is the code:
> 
>     if type(callableObject) is InstanceType:
>         min, d = _paramMinCountFunc(callableObject.__call__.im_func)
>         return min-1, d
>     elif ismethod(callableObject):
>         min, d = _paramMinCountFunc(callableObject.im_func)
>         return min-1, d
>     elif isfunction(callableObject):
>         return _paramMinCountFunc(callableObject)
>     else:
>         raise 'Cannot determine type of callable: '+repr(callableObject)
> 
> I've rewritten it to the following code which passes the tests, also 
> with new-style classes.
> 
>     try:
>         func = callableObject.__call__.im_func
>     except AttributeError:
>         try:
>             func = callableObject.im_func
>         except AttributeError:
>             try:
>                 return _paramMinCountFunc(callableObject)
>             except exc:
>                 raise 'Cannot determine type of callable: %s' % 
> repr(callableObject)
>         else:
>             min, d = _paramMinCountFunc(func)
>             return min-1, d
>     else:
>         min, d = _paramMinCountFunc(func)
>         return min-1, d
> 
> This code looks a bit clumsier than the original one. I don't see a much 
> better way right now though.

It would be nice to not have to duplicate the two else clauses at the end.


> 
> 3) The pubsub question leads me to another question: How to you want to 
> handle SVN access? Should I create a branch which will be merged at the 
> end of the project?

Yes.  I think you'll need it anyway so you can easily extract out the 
changes you've made so you can turn them in to google at the end of the 
summer.


> And how should I deal with patches/fixes which are not related to 
> FloatCanvas (like the one to pubsub above)? Send in a patch on this 
> mailing list and somebody reviews and accepts it?

Yes, or submit a ticket at trac.wxwidgets.org.

-- 
Robin Dunn
Software Craftsman
http://wxPython.org  Java give you jitters?  Relax with wxPython!