Difference between revisions of "cpp/named req/MoveInsertable"
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===Requirements=== | ===Requirements=== | ||
Revision as of 20:18, 2 October 2015
Template:cpp/concept/title Template:cpp/concept/navbar
Specifies that a rvalue of the type can be copied into uninitialized storage.
Requirements
The type T is Template:concept into the Template:concept X if, given
A
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the allocator type defined as X::allocator_type
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m
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the lvalue of type A obtained from X::get_allocator()
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p
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the pointer of type T* prepared by the container
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rv
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rvalue expression of type T, provided as the argument to push_back(), etc
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the following expression is well-formed:
std::allocator_traits<A>::construct(m, p, rv);
And after evaluation, the value of *p is equivalent to the value formerly held by rv (rv remains valid, but unspecified)
Notes
If A is std::allocator<T>, then this will call placement-new, as by ::new((void*)p) T(rv).
If std::allocator<T> or a similar allocator is used, a class does not have to implement a move constructor to satisfy this type requirement: a copy constructor that takes a const T& argument can bind rvalue expressions. If a MoveInsertable class implements a move constructor, it may also implement move semantics to take advantage of the fact that the value of rv after construction is unspecified.
See Also
| Template:concept |
