instance references?

Alex Martelli aleax at
Sun Jan 29 23:44:56 EST 2006

bytecolor <bytecolor at> wrote:

> Thanks Alex, the weak references *seem* to be doing what I want for
> now.
> In each __init__() I use:
> aptbase.drawables.append(weakref.ref(self))
> Then in show():
> for d in aptbase.drawables:
>     o = d()
>     if o is not None:
>         # render it

Looks good, so apparently you didn't particularly care about assignment
to variables vs assignment to other "labels" -- great!

My favourite way to use weakref is slightly different: I would have

aptbase.drawables = weakref.WeakValueDictionary

then in each __init__

aptbase.drawables[len(aptbase.drawables)] = self

then in show:

for o in aptbase.drawables.values():
  # render it

Not a vastly different idiom from yours, mind you, but I like not having
to check whether an object has gone away -- a WeakValueDictionary's
entries just disappear when the value object goes away, so that at any
time looping on its .values() is safe as brick houses!-)


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