Re: [Anygui-devel] And another thing... (signal/kwds)

[Joseph A K. <jk...@ea...>]

Magnus Lie Hetland wrote:
> 
> From: "Patrick K. O'Brien" <po...@or...>
> 
> > I'm a bit confused by this latest change. Wouldn't registering a bound
> > method as a signal handler be the most common case? This is how I picture
> > the previous implementation's most common case:
> [snip]
> 
> Quite a common case, I agree.
> 
> > So shouldn't the common case be the easiest to use?
> 
> Well, it is, isn't it? You can do exactly what you did if you like.
> 
> > And shouldn't it be made to work with weak references?
> 
> As Joe explained, that can't be done, since the method refers to its object
> with a strong reference.
> 
> > And didn't it work with weak references prior to this change?
> 
> It "worked", but the GC problem was there -- and it still is.

There is no GC problem in either case. The "old" way,
if you use a bound method as a handler then the signal code
converts it into a weakref to the object and an unbound
method, and throws away the original bound method object;
so no strong references are retained by the signal code.
The "new" way, you'd have to explicitly pass an object and
an unbound method to get the same effect.

I think Patrick's concern that the common case should be the
simplest is very valid. I'm backing away from the changes
I suggested earlier; I want to look at another alternative
first. I also think (now) that it's probably never a good idea
for the signal code to keep strong references to anything;
if you want to prevent an object from being GC'd it's
simple to keep a global reference to it somewhere.

Sorry to be so fickle, but I think it's important to
get this right.

Cheers,

-- Joe
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