If the values are cached, and the structure implementing the cache has the
same lifetime (or longer? Unsure on that...) as the map then I'd expect it
to work.  For generated/retrieved, non-cached values I don't believe it
would work.
On 2013-09-25 7:54 PM, "Daniel Micay" <[email protected]> wrote:

> On Wed, Sep 25, 2013 at 10:36 PM, David Brown <[email protected]> wrote:
>
>> Let's say I'm implementing some type of map-like structure that I'd
>> like to be able to implement the Map trait on.
>>
>> However, my map doesn't actually store the 'V' directly, but they are
>> computed/retrieve/cached in some manner.
>>
>> Is this possible with the existing map trait?  Given that:
>>
>>  fn find<'a>(&'a self, key: &K) -> Option<&'a V>;
>>
>> doesn't the V need to be a pointer to something with the same lifetime
>> as self?
>>
>> Is there a way of dealing with this, or should I just implement my own
>> similar find function, not implementing Map, and return an Option<V>
>> instead?
>>
>
> The Map trait represents a map storing the values, so it can't be used for
> that use case.
>
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