[PyKDE] Exceptions in callbacks

[Bruce Sass]

Hi,

On 2 Feb 2001, Pete Ware wrote:

> I'm still wondering how to catch an exception that occurs in a slot.
> Supposed I wanted the following exception to print in a dialog box
> instead of to the console.  How?
>
> Thanks,
> --pete
> ----------------------------------------------------------------------
> #! /bin/env python
> #				-*- Python -*-
> import sys
> import qt
>
> class Test (qt.QFrame):
> 	def __init__ (self, parent = None, name = ''):
> 		qt.QFrame.__init__ (self, parent, name)
> 		top = qt.QPushButton ('Exception', self)
> 		top.setMinimumSize (top.sizeHint ())
> 		top.connect (top, qt.SIGNAL ('clicked()'), self.raise_exception)
>
> 	def raise_exception (self):
> 		raise 'An exception.  How can I catch this?'

Hmmm, I'm not sure what you're getting at.  All the program does is
raise an exception when a button is pressed... you're not raising the
exception within the context of anything so you can't trap it before
it causes Qt to abort.  (I'm going from memory 'cause I don't have
PyQt installed right now)

> w = None
> def test ():
> 	global w
> 	app = qt.QApplication (sys.argv)
>
> 	w = Test (None, 'Table')
> 	app.setMainWidget (w)
> 	w.show ()
>
> 	return app
>
> if __name__ == '__main__':
> 	print 'starting app...',
> 	app = test ()
> 	print 'done'

To catch it before it gets to the native os, you should...

try:
> 	app.exec_loop ()
except:
	# handle your exception

...but I don't think it is what you want.

how about...

	def raise_exception(self):
		"""'Exception' button pressed, handle it"""
		try:
			# whatever may cause an exception
		except:
			# what to do if there was an exception
		else:
			# what to do if there was no exception

You should check out the PyQt examples, maybe even compare them to the
Qt tutorials.

HTH


- Bruce