[Python-Dev] RE: [Python-checkins] python/dist/src/Lib weakref.py,1.19,1.20 (original) (raw)

Tim Peters tim_one@email.msn.com
Sun, 25 May 2003 13:17:22 -0400

[Raymond Hettinger]

Arghh. One more example always arises after going to bed.

The original required only equality. The new version requires equality, hashability, and weak referencability.

It always required (and still does) all three for setitem and getitem: key equality and hashability are required for all dicts, and of course key weak referencability is required for a weak-keyed dict: that's why it's called a weak-keyed dict <0.5 wink>.

delitem alone used a bizarre algorithm, and indeed one that broke other normal dict invariants such as that

del d[k]

always deletes the same (key, value) pair that

d[k] = v

would have replaced.