C++ named requirements: EmplaceConstructible (od C++11)
Specifies that an object of the type can be constructed from a given set of arguments in uninitialized storage by a given allocator.
Requirements
The type T is MoveInsertable into the container X whose value_type is identical to T from the arguments args if given
A
an allocator typem
an lvalue of typeA
p
the pointer of typeT*
prepared by the containerargs
zero or more arguments
where X::allocator_type is identical to std::allocator_traits<A>::rebind_alloc<T>
,
the following expression is well-formed:
std::allocator_traits<A>::construct(m, p, args);
If X is not allocator-aware or is a std::basic_string specialization, the term is defined as if A were std::allocator<T>, except that no allocator object needs to be created, and user-defined specializations of std::allocator are not instantiated.
Notes
Although it is required that customized construct is used when constructing elements of std::basic_string until C++23, all implementations only used the default mechanism. The requirement is corrected by P1072R10 to match existing practice.