SF.net SVN: matplotlib:[8723] branches/v1_0_maint/doc/users/event_handling. rst

[<ef...@us...>]

Revision: 8723
          http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8723&view=rev
Author:   efiring
Date:     2010-10-03 20:45:38 +0000 (Sun, 03 Oct 2010)

Log Message:
-----------
docs: in event_handling, note that weak references to callbacks are used.

Modified Paths:
--------------
    branches/v1_0_maint/doc/users/event_handling.rst

Modified: branches/v1_0_maint/doc/users/event_handling.rst
===================================================================
--- branches/v1_0_maint/doc/users/event_handling.rst	2010-09-27 18:51:05 UTC (rev 8722)
+++ branches/v1_0_maint/doc/users/event_handling.rst	2010-10-03 20:45:38 UTC (rev 8723)
@@ -46,6 +46,13 @@
 
     fig.canvas.mpl_disconnect(cid)
 
+.. note::
+   The canvas retains only weak references to the callbacks.  Therefore
+   if a callback is a method of a class instance, you need to retain
+   a reference to that instance.  Otherwise the instance will be
+   garbage-collected and the callback will vanish.
+
+
 Here are the events that you can connect to, the class instances that
 are sent back to you when the event occurs, and the event descriptions
 


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