Which brings up another point; your current
implementation is not thread-safe.  Which is
fine, but you should probably mention that
explicitly in your readme.

>My first implementation of the memory pool
>indeed was using C++11 perfect forwarding to
>call the ctor/dtor of type T when the item was
>pulled out the pool or was returning to it.
>I later removed such feature because I realized
>that calling the ctor of the items to recycle
>produced issues with classes having multiple inheritance IIRC.
>I don't think it's safe and sane to call the
>ctor of the same instance multiple times...Â

Calls must be paired -- you allocate aligned
uninitialised storage (aligned_storage), then
placement-new to call the constructor on that
storage, then eventually call the destructor, and
then later you can placement-new again.

You must never call the constructor twice in a
row or the destructor twice in a row (unless it's
trivial), but alternating is fine.

Again, this is how things like optional and
variant work internally -- and since they do that
part for you, it can be useful to re-use it
rather than re-implementing it.