On Mon, Feb 23, 2015 at 9:29 AM, Laura Creighton <l...@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 -- https://mail.python.org/mailman/listinfo/python-list
