[PyKDE] QObject.insertChild problems

[Phil Thompson]

On Saturday 05 July 2003 10:39 am, Austin Clements wrote:
> 'Lo.  I am implementing a widget that has to layout child widgets in a
> particular way (similar to a QVBox, but not quite), so I tried
> overriding the insertChild method, but found that the objects passed
> to it were always the underlying QObject objects instead of the actual
> widgets I added to it.  Here's a simplification of my code and
> its output:
>
>
> import sys
> from qt import *
>
> class ComponentStack(QWidget):
>     def __init__(self, parent, name="Component stack"):
>         QWidget.__init__(self, parent, name)
>         self.__vbox = QVBoxLayout(self)
>
>     def insertChild(self, obj):
>         print "insertChild(%s)" % `obj`
>         QWidget.insertChild(self, obj)
>         try:
>             self.__vbox.add(obj)
>         except AttributeError: pass
>
> app = QApplication(sys.argv)
> cs = ComponentStack(None)
> app.setMainWidget(cs)
> QPushButton("Button", cs)
> cs.show()
> app.connect(app, SIGNAL('lastWindowClosed()'), app, SLOT('quit()'))
> app.exec_loop()
>
>
> Output:
> insertChild(<qt.QObject instance at 0x81e39ac>)
> insertChild(<qt.QObject instance at 0x81e49b4>)
> Traceback (most recent call last):
>   File "bug.py", line 13, in insertChild
>     self.vbox.add(obj)
> TypeError: Argument 1 of QLayout.add() has an invalid type
>
>
> The first call occurs in the QWidget constructor, before I've created
> the vbox, but the next one, when I add the QPushButton, is the
> problem.  Am I doing something wrong, or is there a better way to do
> this?

I think the problem is that the QPushButton is not fully formed (ie. it's ctor 
hasn't yet completed) by the time it is being passed to its parent's 
insertChild().

A better approach should be to detect the new child by looking for 
QChildEvents which won't be received until the child is fully formed.

Phil