container stuff

[Don]

bearophile wrote:
> Don:
>> When is it better to do it that way, rather than just iterating over all 
>> elements, and then completely empty the container?
>> (Just curious -- I'm having trouble thinking of a use case for this 
>> feature).
> 
> I'm having troubles understanding why two persons have troubles seeing use cases for this feature :-)
> 
> Iterating over the container and then emptying the container is two operations, you have to keep in mind to empty it, while if you pop items out of it progressively you just need to keep in mind to do one thing, and you avoid forgetting the final cleaning.

Yes, but if I understand correctly, the only reason to have removeAny 
_as a primitive_ is for speed. And iterating over the container followed 
by a single removal is almost always going to be much faster.

If, however, speed is not critical, removeAny can be a generic function 
-- call removeFront() if present, else call removeBack().
And your examples would work just fine with that.

I'm having trouble identifying a use case where it needs to be a primitive.