[wxPython-dev] 20070802 test build uploaded

[Robin Dunn]

Mike Rooney wrote:
> R'bot wrote:
>> Hi,
>>
>> A new test build of wxPython has been uploaded. 
>>    Version: 2.8.4.2.20070802
>>    URL:     http://wxPython.wxcommunity.com/preview/20070802
>>    Changes: http://wxPython.wxcommunity.com/preview/20070802/CHANGES.html
>>   
> 
> 
> "Added some SWIG magic that allows wx C++ lists to be exposed to 
> wxPython as sequence-like wrappers around the real list, instead of 
> making a Python list that is a copy of the real list as was done before. 
> These sequence-like objects support indexing, iteration and containment 
> tests ("obj in seq") but not anything that would modify the sequence. If 
> you need to have a real list object like before you can pass the 
> sequence to Python's list() function to convert it."
> 
> Nice, I like where this is going! The containment tests are a step up to 
> be sure, but there doesn't appear to be a way to get the index. Is this 
> possible? ( I realize of course that I can loop over it manually and 
> discover it this way).

Adding index() is on my ToDo list.  I'll give it a try today or 
tomorrow.  The problem is that while it is probably easy to implement 
for the typical use of seq.index(obj), there isn't a direct corellation 
in the C++ list class to be able to do seq.index(obj, start, stop) so it 
would take a bit of work to make that happen correctly...


> 
>  >>> children = sizer.GetChildren()
>  >>> sizerItem in children #good!
> True
>  >>> children.index(sizerItem) #oh no, I guess it has to be a list
> Traceback (most recent call last):
> ...
> AttributeError: 'SizerItemList' object has no attribute 'index'
>  >>> sizerItem in list(children) #but then containment fails
> False
>  >>> list(children).index(sizerItem) #and this as well
> Traceback (most recent call last):
> ...
> ValueError: list.index(x): x not in list
> 
> As you see I can turn it into a Python list to get the index method but 
> then the containment test fails as well as the index then.

This is actually a different problem related to wx.SizerItems, if you do 
it with one of the window lists it should work as expected.  For example:

  >>> import wx
  >>>
  >>> for x in range(5):
  ...     f = wx.Frame(shell, title=str(x))
  ...     f.Show()
  ...
  True
  True
  True
  True
  True
  >>> seq = wx.GetTopLevelWindows()
  >>> seq
  wxWindowList: [<wx.py.shell.ShellFrame; proxy of <Swig Object of type 
'wxFrame *' at 0x877ae28> >, <wx._windows.Frame; proxy of <Swig Object 
of type 'wxFrame *' at 0x8b7ed00> >, <wx._windows.Frame; proxy of <Swig 
Object of type 'wxFrame *' at 0x888d348> >, <wx._windows.Frame; proxy of 
  <Swig Object of type 'wxFrame *' at 0x8b80cd0> >, <wx._windows.Frame; 
  proxy of <Swig Object of type 'wxFrame *' at 0x8b82ce0> >, 
<wx._windows.Frame; proxy of <Swig Object of type 'wxFrame *' at 
0x8b83fe8> >]
  >>> f
  <wx._windows.Frame; proxy of <Swig Object of type 'wxFrame *' at 
0x8b83fe8> >
  >>> f in seq
  True
  >>> f in list(seq)
  True
  >>> list(seq).index(f)
  5
  >>>

I think the problem with wx.SizerItem is that it is not OOR sensitive. 
In other words I'm not saving a reference to the Python proxy object in 
the C++ object, so when SWIG needs to give you a proxy for the C++ 
object it creates a new one.  So doing Python-level compares results in 
comparing two different Python objects that happen to be proxies for the 
same C++ object, and since there is no __cmp__ magic methods it just 
checks if you are looking at the same object and then fails.  I'll give 
this some more thought and see if there's an easy way to make this work 
better.

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