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Re: Design thought for callbacks

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On Mon, Feb 23, 2015 at 9:29 AM, Laura Creighton <lac@openend.se> wrote:
> But that is not so surprising.  How many people use WeakSets for
> _anything_?  I've never used them, aside from 'ooh! cool shiny
> new language feature!  Let's kick it around the park!'  That people
> aren't familiar with WeakSets doesn't mean all that much.

I haven't used weak *sets*, but I've used weak *mappings* on occasion.
It's certainly not a common thing, but they have their uses. I have a
MUD which must guarantee that there be no more than one instance of
any given room (identified by a string that looks like a Unix path),
but which will, if it can, flush rooms out of memory when nothing
refers to them. So it has a mapping from the path strings to the
instances, but with weak refs for the instances; if anything else is
referring to that instance (eg a player character in the room), it'll
hang around, and any time anyone else needs that room, they'll get the
same instance back from the mapping; but any time the garbage
collector notices that a room can be disposed of, it will be.

Definitely not common though.

ChrisA

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Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-21 09:07 -0500
  Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-22 04:27 +1100
    Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-22 08:13 -0500
      Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-24 00:31 +1100
    Re: Design thought for callbacks Ethan Furman <ethan@stoneleaf.us> - 2015-02-22 13:02 -0800
    Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-22 16:17 -0500
      Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-22 23:34 +0200
        Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-22 17:09 -0500
        Re: Design thought for callbacks Laura Creighton <lac@openend.se> - 2015-02-22 23:29 +0100
        Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-23 09:41 +1100
        Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-23 06:47 -0500
        Re: Design thought for callbacks "Frank Millman" <frank@chagford.com> - 2015-02-23 14:29 +0200
        Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-24 06:00 -0500

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