...one of the most highly
regarded and expertly designed C++ library projects in the
world. — Herb Sutter and Andrei
template <class T> struct has_trivial_destructor : public
Inherits: If T is a (possibly cv-qualified) type with a trivial destructor then inherits from true_type, otherwise inherits from false_type.
If a type has a trivial destructor then the destructor has no effect: calls to the destructor can be safely omitted. Note that using meta-programming to omit a call to a single trivial-constructor call is of no benefit whatsoever. However, if loops and/or exception handling code can also be omitted, then some benefit in terms of code size and speed can be obtained.
Compiler Compatibility: Without some (as
yet unspecified) help from the compiler, has_trivial_destructor will never
report that a user-defined class or struct has a trivial destructor; this
is always safe, if possibly sub-optimal. In addition, in order to correctly
handle deleted or private destructors then support for C++11's
decltype is required. Currently (June 2015)
compilers more recent than Visual C++ 8, GCC-4.3, Greenhills 6.0, Intel-11.0,
and Codegear have the necessary compiler intrinsics
to ensure that this trait "just works". You may also test to see
if the necessary intrinsics
are available by checking to see if the macro
C++ Standard Reference: 12.4p3.
has_trivial_destructor<char*>::typeis the type
has_trivial_destructor<int (*)(long)>::valueis an integral constant expression that evaluates to true.
has_trivial_destructor<MyClass>::valueis an integral constant expression that evaluates to false.
has_trivial_destructor<T>::value_typeis the type