Proposal for std::vector.

[Matt Austern]

On Feb 9, 2004, at 6:20 PM, Gabriel Dos Reis wrote:

> Matt Austern <austern@apple.com> writes:
>
> | I'm afraid you're right too.  Fortunately, I really do only mean "a
> | bit" more
> | complicated.  The solution is pretty simple: instead of inheriting
> | directly
> | from the allocator, instead inherit from a thin wrapper class that
> | provides
> | nothing but the allocator functions we care about.
>
>
> Just to make sure I understand your suggestion.  In doing so, how do
> we prevent the "virtual function is a sin you inherit from your
> descendents" syndrom and benefit at the same time from the empty base
> optimization?
>
> The solution I'm thinking of would be:
>
>   template<class Allocator>
>     WrapAllocator {
>        Allocator allocator;
>        // standard allocator interface goes here
>        // as forwarding functions to Allocator
>        // ...
>     };
>
>   template<class T, class Allocator = allocator<T> >
>     struct vector : private WrapAllocator<Allocator> {
>       // ...
>     };
>
> Is that what you're alluding to?

Basically, yes.  The two ways in which this isn't *exactly* what I
have in mind:
  (1) It won't be the full standard allocator interface, only the
      useful part.  (i.e. "allocate" and "deallocate".)
  (2) Two template parameters, not one.  As long as we have to
      introduce this wrapper class anyway, may as well make it
      do double duty by having it take care of the icky rebind
      stuff.

			--Matt