On Fri, May 21, 2010 at 05:57:00PM +0200, Alessandro Dentella wrote:
> Hi,
>
> I'm trying to figure out the correct way to delete a class that builds
> GUI.
>
> I was not able to delete the object from a callback in a clean way.
>
> The following code should demostrate what I mean::
>
> import weakref
> import gtk
> import gobject
>
> class A(object): pass
>
>
> class G(object):
> def __init__(self):
> self.a = A()
> self.w = gtk.Window()
> self.w.show()
> self.w.connect_after('delete-event', self.delete_event_cb)
>
> def delete_event_cb(self, win, ev):
> print 'killed'
> del self
> print "s", s() # I'd like to see this to become None
> gtk.main_quit()
>
> g = G()
>
> s = weakref.ref(g.a)
>
> gtk.main()
>
> My goal is to create a class 'G' that will destroy itself completely
> when the window it holds receives a "delete_event".
>
> As written in the comment, I'd like to see that the weakref to an element
> inside the instance 'g' should be None after deletion of 'g'. But it's not!
>
> Deleteing the object prints:
>
> san...@bluff: $ python test_mem.py
> killed
> s <__main__.A object at 0x8329eec>
>
> If I get rid of 'self'in the callback, everithing works but that makes
> it impossible to put the function inside the class.
>
> If I use a delete_event_cb as a separate function I manage to destroy it if
> I don't pass the g object as argument to the callbac (ie: making it global)
> but clearly that's a far less usefull setup.
>
> What's the best practice to delete compound widgets?
Further tests on this showed me that if I set data on a widget
(e.g. using set_data) that contitues a strong reference that will not let
the gc to delete the object::
import gc
import sys
import weakref
import gtk
class G(object):
def __init__(self):
self.w = gtk.Window()
self.w.show()
self.w.set_data('obj', self) # this reference keeps 's' "alive"
self.w.connect_after('delete-event', self.delete_event_cb)
self.w.connect('enter-notify-event', self.enter_event_cb)
def delete_event_cb(self, win, ev):
print 'killed'
def enter_event_cb(self, win, ev):
global s
print 'enter', s()
s = weakref.ref(G())
print s()
try:
gtk.main()
except KeyboardInterrupt:
print s()
sys.exit(1)
I'd say this is a bug, am I wrong? is this a known problem?
That clearly leads to memory leaks.
Any hints?
sandro
*:-)
--
Sandro Dentella *:-)
http://sqlkit.argolinux.org SQLkit home page - PyGTK/python/sqlalchemy
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