Re: [Pyobjc-dev] NSUndoManager.prepareWithInvocationTarget_

[<bb...@ma...>]

On Monday, Dec 30, 2002, at 15:06 US/Eastern, Ronald Oussoren wrote:
> I expected that this would work, but it clearly doesn't. This seems to 
> be caused by a misunderstanding on my part of the semantics of 
> 'NSObject.respondsToSelector:'. I expected that this returns true 
> whenever 'NSObject.methodSignatureForSelector:' returns a non-nil 
> value, but it doesn't.

This is frequently not the case in the context of forwarded invocations 
and other proxy-like behavior.  A class may return true to 
respondsToSelector: but not actually provide a signature for the 
selector.

NSUndoManager is just a big proxy that keeps invocations in a stack-- 
it isn't surprising that the behavior of respondsToSelector: in the 
context of undo is a bit odd.