wxPython and multiple inheritance

Question

I know that Python, unlike Java, supports inheritance. But does a user class can inherits from several wxPython class without any problem ? (Does the wxPython design allows this ?)

Thank you in advance

I'm coding under Xubuntu 11.04 with wxPython 2.8 binding

P.S : This is my attempt.

#!/usr/bin/python
# -*- coding: iso-8859-15 -*-

import wx

class Square(wx.Panel, wx.Control):

    def __init__(self, parent):
        wx.Panel.__init__(self, parent, wx.ID_ANY, size=(60,60), pos=(80,50))
        wx.Control.__init__(self, parent)
        self.SetBackgroundColour(wx.Colour(0,0,255))

class MainFrame(wx.Frame):

    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Reactive square application",
            size = (300,200))
        panel = wx.Panel(self, wx.ID_ANY)
        square1 = Square(panel)
        square2 = Square(panel)
        square1.Bind(wx.EVT_BUTTON, self.OnSquareClick)

    def OnSquareClick(self, event):
        dialog = wx.MessageDialog(self, "You clicked on square !!!",
            "Hit has been done", wx.OK)
        dialog.Show(True)


if __name__ == "__main__":
    app = wx.PySimpleApp()
    frame = MainFrame()
    frame.Show(True)
    app.MainLoop()

And this is the stack trace :

swig/python detected a memory leak of type 'wxControl *', no destructor found. Traceback (most recent call last): File "/home/laurent/Documents/Programmation/Projets/Python/SourcesDeTest/ReactiveSquare.py", line 31, in frame = MainFrame() File "/home/laurent/Documents/Programmation/Projets/Python/SourcesDeTest/ReactiveSquare.py", line 19, in init square1 = Square(panel) File "/home/laurent/Documents/Programmation/Projets/Python/SourcesDeTest/ReactiveSquare.py", line 10, in init wx.Control.init(self, parent) File "/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py", line 11718, in init self._setOORInfo(self) File "/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py", line 3887, in _setOORInfo args[0].this.own(False) File "/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py", line 14606, in getattr raise PyDeadObjectError(self.attrStr % self._name) wx._core.PyDeadObjectError: The C++ part of the Square object has been deleted, attribute access no longer allowed. Script terminated.

Mike Driscoll · Accepted Answer · 2011-10-06 19:13:50Z

1

You don't really want to do multiple inheritance with wxPython classes UNLESS they're a normal wx class plus a mixin (see g.d.d.c's answer). Or a wxPython class and a user-defined class. Otherwise, you will probably have issues.

answered Oct 6, 2011 at 19:13

Mike Driscoll

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1 Comment

loloof64 Over a year ago

Ok, i didn't know about mixin classes. I'm going to search for a good introduction on Google. Because I think that the second solution (wxPython sub + my own class) will also be difficult to make it work

g.d.d.c · Accepted Answer · 2011-10-06 18:48:52Z

1

Inheritance from multiple parent classes is definitely possible, yes.

http://docs.python.org/tutorial/classes.html#multiple-inheritance

I don't seem to run into any trouble using multiple base classes, wx classes included:

class VirtualList(ListCtrl):
  def __init__(self,
               parent,
               colref = None,
               style = LC_REPORT | LC_VIRTUAL | LC_HRULES | LC_VRULES):

    ListCtrl.__init__(self, parent, style = style)

class TransformList(VirtualList, CheckListCtrlMixin):
  def __init__(self, parent, refid):
    VirtualList.__init__(self, parent, colref = 'transform_columns')

    CheckListCtrlMixin.__init__(self)

    # This facilitates drag / drop re-ordering.
    self.Bind(wx.EVT_LIST_BEGIN_DRAG, self._startDrag)

    dt = ListDrop(self._reorder)

    self.SetDropTarget(dt)

edited Oct 6, 2011 at 18:48

answered Oct 6, 2011 at 18:02

g.d.d.c

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2 Comments

loloof64 Over a year ago

yes, I did know it, as I said in my first post. But it seems that I run into problems trying to applying inheritance with wxPython classes

g.d.d.c Over a year ago

@LaurentBERNABE - It would allow us to help you more if you demonstrated code of yours that does not seem to work well with multiple inheritance.

joaquin · Accepted Answer · 2011-10-08 12:36:48Z

1

It is my experience that wxPython does not encourage multiple inheritance of wxPython classes.

Doing something like this will either cause errors or unexpected consequences with your new class:

class MyControl(wxButton, wxComboBox):
    pass

However, you can use multiple inheritence to inherit a wxPython class and your own class in order to extend it in a more OO kind of way.

 class ControlActions(object):
     def MoveHere(self):
          pass

 class MyControl(wxButton, DoActions):
     pass

edited Oct 8, 2011 at 12:36

joaquin

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answered Oct 6, 2011 at 18:11

viper34j

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1 Comment

loloof64 Over a year ago

Hmm, that won't solve my problem. But thank you. In fact, i want to inherit both from wxPanel and wxControl => that way I hope to draw multiple blue squares that reacts to wxEVT_BUTTON event. But I ran into a serious exception. I also tried to use PlateButton, but I did not manage to give it the simple box apperance i wanted.

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