I know that it deprecated and removed only in std::allocator. And I can implement it on my own allocators. But why it is deprecated?
CodePudding user response:
rebind
was a clunky, pre-C 11 way of taking an allocator type for T
and converting it into an allocator type for U
. I say "pre-C 11" because C 11 gave us a much more convenient way to do it: template aliases.
allocator_traits
template has a member template alias rebind<U>
that computes Allocator<U>
for the allocator it is a trait for. It can use the rebind
member of the allocator if it is available, otherwise, it just yields Allocator<U>
.
allocator_traits
effectively defines a lot of functionality that std::allocator
used to provide. This made a lot of members of std::allocator
redundant, so they have been deprecated and removed in favor of the traits
-based defaults.