[Python-Dev] Add a frozendict builtin type

[Nick Coghlan]

On Thu, Mar 1, 2012 at 7:29 PM, André Malo <nd at perlig.de> wrote:
> - Caching. My data container objects (say, resultsets from a db or something)
>  usually inherit from list or dict (sometimes also set) and are cached
>  heavily. In order to ensure that they are not modified (accidentially), I
>  have to choices: deepcopy or immutability. deepcopy is so expensive, that
>  it's often cheaper to just leave out the cache. So I use immutability. (oh
>  well, the objects are further restricted with __slots__)

Speaking of caching - functools.lru_cache currently has to do a fair
bit of work in order to correctly cache keyword arguments. It's
obviously a *solvable* problem even without frozendict in the
collections module (it just stores the dict contents as a sorted tuple
of 2-tuples), but it would still be interesting to compare the
readability, speed and memory consumption differences of a version of
lru_cache that used frozendict to cache the keyword arguments instead.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia