WeakKeyIdDict implementation (keeping WeakKeyDict)

[mauro3]

Procrastinating this morning I coded up an implementation of both WeakKeyDict and WeakKeyIdDict.

TODO:

• go through stdlib/ and check whether the Id version should be used (note WeakKeyDict is not used in base/): occurrence 1 (According to Jeff this is needs a WeakKeyDict), occurrence 2 (According to Jeff this is needs a WeakKeyDict), occurrence 3
• Someone needs to check that the constructors are ok.
• ponder whether WeakRefs should compare as Refs do, see WeakKeyDict based on object ids #3002 (comment) (which could be done trivially within this PR)

x-refs: #3002, #24941, #28161

[mauro3]

The build failures are because of a mistake in the collections.md making the doc-generation fail. To preserve CI time, I'll only push a fix if this PR is deemed useful.

[mauro3]

If this is something to consider for 1.x, please add the milestone. Otherwise close.

[HechtiDerLachs]

Hello everyone!

I was wondering: Can this still be used? I mean: I see that there are conflicts for this to be merged straight away, but maybe one can still take the code and build a working WeakKeyIdDict from it which is compatible with the current version of julia?

I am asking because this would really be helpful for what I am doing in the Oscar.jl project right now. Thanks for any assessment or suggestions!

[mauro3]

Not sure this will ever get merged (and that is probably good, considering it does not get too much interest ;-). If you need this, you probably should use it via JuliaCollections/DataStructures.jl#402, which does not get merged either ;-)