[Python-Dev] caching in the stdlib? (original) (raw)

Stefan Behnel stefan_ml at behnel.de
Wed Jul 28 16:47:48 CEST 2010

I think this is better suited for python-ideas, so moving it there.

Guido van Rossum, 28.07.2010 16:31:

On Tue, Jul 27, 2010 at 10:29 PM, Stefan Behnel wrote:

What about actually putting it visibly into the stdlib? Except for files, I didn't see much about caching there, which seems like a missing battery to me. Why not do it as with the collections module and add stuff as it comes in? Caching is a rather large topic to focus on in a single stdlib module or package. It means radically different things to different people.

Sure. All I would like to see in the stdlib is a dict based cache with a bounded size and a set of different policies that keep it at that size.

Maybe a BoundedDict would match that need.

The pattern we're talking about there is probably more something like memoization, so 'memo' or 'memoization' could b a reasonable module name.

That would be a second interface to it, I'd say. The normal interface would just be the regular mapping interface, maybe even just a .get() method instead of a KeyError raising lookup.

Maybe it could provide a decorator that you configure with things like how many entries max, the expiration policy (or different policies could have different decorators), and how to compute the memo key from the arguments to the function (the default could be the repr() of the argument tuple).

Absolutely.

Stefan

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