Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards



template <class T>
struct has_trivial_move_assign : public true_type-or-false_type {};

Inherits: If T is a (possibly cv-qualified) type with a trivial move assignment-operator then inherits from true_type, otherwise inherits from false_type.

If a type has a trivial move assignment-operator then the operator has the same effect as copying the bits of one object to the other: calls to the operator can be safely replaced with a call to memcpy.

Compiler Compatibility: Without some (as yet unspecified) help from the compiler, has_trivial_move_assign will never report that a user-defined class or struct has a trivial move assign; this is always safe, if possibly sub-optimal. In addition, in order to correctly handle private or deleted move assignment operators then c++11's decltype is required. Currently (June 2015) compilers that have the necessary intrinsics to ensure that this trait "just works" include Clang, GCC-5.1 and MSVC-12.0. You may also test to see if the necessary intrinsics are available by checking to see if the macro BOOST_HAS_TRIVIAL_MOVE_ASSIGN is defined.

Header: #include <boost/type_traits/has_trivial_move_assign.hpp> or #include <boost/type_traits.hpp>


has_trivial_move_assign<int> inherits from true_type.

has_trivial_move_assign<char*>::type is the type true_type.

has_trivial_move_assign<int (*)(long)>::value is an integral constant expression that evaluates to true.

has_trivial_move_assign<MyClass>::value is an integral constant expression that evaluates to false.

has_trivial_move_assign<T>::value_type is the type bool.