[IronPython] Issues with methods as event handlers?

[Dino Viehland]

Another option that should work is:

class ClickListener:
	def trigger(self, source, args):
		print "..."

a = ClickListener()
b = a.trigger

triggerButton.Click += b

triggerButton.Click -= b


What you're experiencing is the fact that trigger is actually just a callable object.  When you do a.trigger you get a new bound method object that is different from the bound method object you get back when you do the -=.

We should see if there's a way for us to fix this to match expecations so I'll go ahead and make sure we get the bug filed.


-----Original Message-----
From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Giles Thomas
Sent: Wednesday, February 01, 2006 11:10 AM
To: Discussion of IronPython
Subject: [IronPython] Issues with methods as event handlers?

Hi all,

When we use bound methods as Windows Forms event handlers, we can't 
detach them.  Functions work OK.

To see the problem, run up the attached button_method.py using 
IronPythonConsole; if you click on the "Trigger" button, you'll see a 
log message in the console saying that the trigger method has been 
called.  Click on the "Remove" button to remove the event handler, and 
then click on the "Trigger" button again - you'll still get the log 
message.  So the event handler was not detached correctly.

By contrast, if you do the same thing using button_function.py, you will 
see that once you have clicked on "Remove", the "Trigger" button's 
handler will be correctly detached, so further clicks on that button 
will not generate log messages.

We've tested against beta 2, beta 1, and 0.9.5 (which latter doesn't 
display the button labels but otherwise behaves as described above).

Hope this helps someone :-)


Cheers,

Giles
-- 
Giles Thomas
Resolver Systems
giles.thomas at resolversystems.com
We're hiring! http://www.resolversystems.com/jobs/