That's similar to my use case. Big mutable object (right now a state in a multi-agent simulation) with lots of methods that I want to cache.
"Given that it's not really hard to write your own caching decorator, I don't feel like this needs to change the API of lru_cache." Well, given that it's not really hard to write your own caching decorator, why is lru_cache in the standard library to begin with? ;) On Fri, Oct 16, 2020 at 7:31 AM Carl Meyer <c...@oddbird.net> wrote: > On Thu, Oct 15, 2020 at 3:33 PM David Mertz <me...@gnosis.cx> wrote: > > So the use case needs to be: > > > > * Function operates on large objects > > * Function operates on large, immutable objects > > * Function never takes literal or computed arguments (i.e. not > `fun(big1+big2)`) > > * Large immutable objects are deleted selectively (OK, this is plausible) > > * The performance hit of clearing entire cache is not suitable > > One real-world use case I've seen personally that meets all these > criteria is per-request memoization of expensive work in a server > application (using an `lru_cache`-like decorator on functions taking > the request as an argument.) The request object plus things hanging > off it can be quite large, it's often effectively immutable (at least > inasmuch as the functions so decorated care), it's desirable for all > cached data for a request to expire as soon as handling for the > request is finished, but you wouldn't want to fully clear the caches > (e.g. the application may handle multiple requests concurrently, so > other requests may still be in-flight.) > > > Given that it's not really hard to write your own caching decorator, I > don't feel like this needs to change the API of lru_cache. > > But I don't disagree with this conclusion. There are often other > specific needs that would mandate a custom decorator anyway. > > Carl >
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