std::uses_allocator
| Defined in header
<memory>
|
||
| template< class T, class Alloc >
struct uses_allocator |
(since C++11) | |
If T has a member typedef allocator_type which is convertible from Alloc, provides the member constant value equal to true. Otherwise value is false.
Contents |
Inherited from std::integral_constant
Member constants
| value
[static]
|
true if T uses allocator Alloc, false otherwise (public static member constant) |
Member functions
| operator bool |
converts the object to bool, returns value (public member function) |
| operator()
(C++14)
|
returns value (public member function) |
Member types
| Type | Definition |
value_type
|
bool
|
type
|
std::integral_constant<bool, value> |
[edit] Specializations
Custom specializations of the type trait std::uses_allocator are allowed for types that do not have the member typedef allocator_type but satisfy one of the following two requirements:
1) T has a constructor which takes std::allocator_arg_t as the first argument, and Alloc as the second argument.
2) T has a constructor which takes Alloc as the last argument.
The following specializations are already provided by the standard library:
| (C++11)
|
specializes the std::uses_allocator type trait (class template specialization) |
| (C++11)
|
specializes the std::uses_allocator type trait (function template) |
| specializes the std::uses_allocator type trait (function template) |
|
| (C++11)
|
specializes the std::uses_allocator type trait (function template) |
| specializes the std::uses_allocator type trait (class template specialization) |
|
| specializes the std::uses_allocator type trait (class template specialization) |
|
| specializes the std::uses_allocator type trait (class template specialization) |
[edit] Notes
This type trait is used by std::scoped_allocator_adaptor and may be used by custom allocators to determine whether the object being constructed is itself capable of using an allocator (e.g. is a container), in which case an allocator should be passed to its constructor.
[edit] See also
| (C++11)
|
an object of type std::allocator_arg_t used to select allocator-aware constructors (constant) |
| (C++11)
|
tag type used to select allocator-aware constructor overloads (class) |
| (C++11)
|
implements multi-level allocator for multi-level containers (class template) |