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|wxALL, 15)
  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         win = evt.GetEventObject()
  63         if win is None:
  64             self.log.write("***** OOPS! None returned...\n")
  65             return
  66         if win is self.btn2:
  67             self.log.write("The objects are the same! <grin>\n")
  68         else:
  69             self.log.write("The objects are NOT the same! <frown>\n")
  70
  71
  72 #----------------------------------------------------------------------
  73
  74 def runTest(frame, nb, log):
  75     win = TestPanel(nb, log)
  76     return win
  77
  78 #----------------------------------------------------------------------
  79
  80
  81 overview = """\
  82 <html><body>
  83 <h2>Original Object Return</h2>
  84
  85 <p>Several methods in wxWindows return pointers to base class objects,
  86 when in fact the actual object pointed to is of a derived type.  Since
  87 SWIG isn't able to tell the actual type it just creates a new Python
  88 shadow object of the base type to wrap around the base type pointer
  89 and returns it.
  90
  91 <p>In wxPython prior to 2.3.0 this could cause annoying issues.  For
  92 example if you called:
  93
  94 <pre>
  95
  96         myText = someWindow.FindWindowById(txtID)
  97 </pre>
  98
  99 expecting to get a wxTextCtrl you would actually get a wxWindow object
 100 instead.  If you then try to call SetValue on that object you'll get
 101 an exception since there is no such method.  This is the reason for
 102 the wxPyTypeCast hack that has been in wxPython for so long.
 103
 104 <p>Even with wxPyTypeCast there was the issue that the object returned
 105 was not the same one that was created in Python originally, but a new
 106 object of the same type that wraps the same C++ pointer.  If the
 107 programmer has set additional attributes of that original object they
 108 will not exist in the new object.
 109
 110 <p>For a long time now I have wanted to do away with wxPyTypeCast and
 111 also find a way to return the original Python object from methods like
 112 FindWindowById.  This project naturally divides into two phases:
 113
 114 <p><ol>
 115
 116 <li>Teach the wrapper methods how to return objects of the right type,
 117 and be able to then turn wxPyTypeCast in to a no-op.
 118
 119 <li>Be able to return the original Python shadow object if it still exists.
 120
 121 </ol>
 122
 123 <p>The first button below shows the first of these phases (<i>working</i>)
 124 and the second will show #2 (<i>working as of 2.3.2</i>)
 125
 126 </body></html>
 127 """