[boost] Re: How much should I care about allocators?

From: Tom Widmer (tom_usenet_at_[hidden])
Date: 2005-03-23 09:57:42

Michael Stevens wrote:

> GCC is correct. There is a get out clause in the library standard. Look at 
> section 20.1.5 "Allocator requirements" paragraph 4:
> 
> Implementations of containers described in this International Standard are 
> permitted to assume that their Allocator template parameter meets the 
> following two additional requirements beyond those in Table 32.   All 
> instances of a given allocator type are required to be interchangeable and 
> always compare equal to each other.   The typedef members pointer, 
> const_pointer, size_type, and difference_type are required to be T*, T 
> const*, size_t, and ptrdiff_t, respectively.
> 
> I suspect many implementation (including those not in the standard) have this 
> requirement!

Dinkumware's library doesn't. It is certainly something to strive for 
when writing a container, since otherwise your container cannot be used 
with certain useful allocators.

Tom