[Python-Dev] Add a frozendict builtin type (original) (raw)

Victor Stinner victor.stinner at haypocalc.com
Tue Feb 28 13:17:47 CET 2012

A frozendict can be used as a member of a set or as a key in a dictionary.

For example, frozendict is indirectly needed when you want to use an object as a key of a dict, whereas one attribute of this object is a dict. It isn't. You just have to define hash correctly.

Define hash on a mutable object can be surprising.

Or do you mean that you deny somehow the modification of the dict attribute, and convert the dict to a immutable object before hashing it?

frozendict helps also in threading and multiprocessing. How so?

For example, you don't need a lock to read the frozendict content, because you cannot modify the content.

Victor

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