peek_lru method for custom eviction policies

[g2p]

I'd like to be able to wrap the LRU and implement a custom eviction policy, that will protect certain elements from removal but still make them part of the LRU ordering.
For that I need something like a peek_lru method, that behaves like a peek for the least-recently used element (consistent with existing peek and pop_lru methods).
Then I can implement updates to the LRU by checking if we are at capacity, if so peek if the key is not in the LRU cache and check if the LRU element is protected, if so error out, otherwise proceed with setting.

[jeromefroe]

If I understand correctly, the proposed method would be similar to pop_lru except it wouldn't remove the element from the cache?

[g2p]

Yes, that is correct

[jeromefroe]

That seems pretty reasonable to me, I should be able to put up a diff in the next couple of weeks.

[jeromefroe]

@g2p I just put up PR #16 which adds a peek_lru method to the cache with what I think is the desired behavior, namely returning the key and value of the least recently used item in the cache if it exists. Mind taking a look and letting me know what you think when you get some cycles?

[g2p]

@jeromefroe The PR is exactly what I need, thank you. Apologies for the delay.

[jeromefroe]

Just released 0.1.10 which contains the peek_lru method.