wxPython/demo/OOR.py

   1
   2 from wxPython.wx import *
   3 from wxPython.html import *
   4
   5 #----------------------------------------------------------------------
   6
   7 BTN1 = wxNewId()
   8 BTN2 = wxNewId()
   9
  10
  11 class TestPanel(wxPanel):
  12     def __init__(self, parent, log):
  13         wxPanel.__init__(self, parent, -1)
  14         self.log = log
  15
  16         sizer = wxBoxSizer(wxVERTICAL)
  17         html = wxHtmlWindow(self, -1)
  18         html.SetPage(overview)
  19         sizer.Add(html, 1, wxEXPAND|wxALL, 5)
  20
  21         btns = wxBoxSizer(wxHORIZONTAL)
  22         btns.Add(50, -1, 1, wxEXPAND)
  23         btn1 = wxButton(self, BTN1, "Find My Alter-ego")  # don't save a ref to this one
  24         btns.Add(btn1)
  25         btns.Add(50, -1, 1, wxEXPAND)
  26         self.btn2 = wxButton(self, BTN2, "Find Myself")
  27         btns.Add(self.btn2)
  28         btns.Add(50, -1, 1, wxEXPAND)
  29
  30         sizer.Add(btns, 0, wxEXPAND|wxLEFT|wxRIGHT|wxBOTTOM, 5)
  31
  32         self.SetSizer(sizer)
  33         self.SetAutoLayout(true)
  34
  35         EVT_BUTTON(self, BTN1, self.OnFindButton1)
  36         EVT_BUTTON(self, BTN2, self.OnFindButton2)
  37
  38
  39     def OnFindButton1(self, evt):
  40         win = self.FindWindowById(BTN1)
  41         if win is None:
  42             self.log.write("***** OOPS! None returned...\n")
  43             return
  44         className = win.__class__.__name__
  45         if className in ["wxButton", "wxButtonPtr"]:
  46             self.log.write("The types are the same! <grin>\n")
  47         else:
  48             self.log.write("Got %s, expected wxButton or wxButtonPtr\n" % className)
  49
  50
  51
  52     def OnFindButton2(self, evt):
  53         win = self.FindWindowById(BTN2)
  54         if win is None:
  55             self.log.write("***** OOPS! None returned...\n")
  56             return
  57         if win is self.btn2:
  58             self.log.write("The objects are the same! <grin>\n")
  59         else:
  60             self.log.write("The objects are NOT the same! <frown>\n")
  61
  62
  63 #----------------------------------------------------------------------
  64
  65 def runTest(frame, nb, log):
  66     win = TestPanel(nb, log)
  67     return win
  68
  69 #----------------------------------------------------------------------
  70
  71
  72 overview = """\
  73 <html><body>
  74 <h2>Original Object Return</h2>
  75
  76 <p>Several methods in wxWindows return pointers to base class objects,
  77 when in fact the actual object pointed to is of a derived type.  Since
  78 SWIG isn't able to tell the actual type it just creates a new Python
  79 shadow object of the base type to wrap around the base type pointer
  80 and returns it.
  81
  82 <p>In wxPython this can cause annoying issues.  For example if you
  83 call:
  84
  85 <pre>
  86
  87         myText = someWindow.FindWindowById(txtID)
  88 </pre>
  89
  90 expecting to get a wxTextCtrl you will actually get a wxWindow object
  91 instead.  If you then try to call SetValue on that object you'll get
  92 an exception since there is no such method.  This is the reason for
  93 the wxPyTypeCast hack that has been in wxPython for so long.
  94
  95 <p>Even with wxPyTypeCast there is the issue that the object returned
  96 is not the same one that was created in Python originally, but a new
  97 object of the same type that wraps the same C++ pointer.  If the
  98 programmer has set additional attributes of that original object they
  99 will not exist in the new object.
 100
 101 <p>For a long time now I have wanted to do away with wxPyTypeCast and
 102 also find a way to return the original Python object from methods like
 103 FindWindowById.  This project naturally divides into two phases:
 104
 105 <p><ol>
 106
 107 <li>Teach the wrapper methods how to return objects of the right type,
 108 and be able to then turn wxPyTypeCast in to a no-op.
 109
 110 <li>Be able to return the original Python shadow object if it still exists.
 111
 112 </ol>
 113
 114 <p>The first button below shows the first of these phases (<i>working</i>)
 115 and the second will show #2 (<i>not yet working.</i>)
 116
 117 </body></html>
 118 """