enable_if< B, T > Struct Template Reference

#include <elm/meta.h>

Detailed Description

template<bool B, class T = void>
struct elm::meta::enable_if< B, T >

This meta-structure is useful to define a type that depends on a condition, usually #SFINAE function. If the condition B is true, the returned type contains a type named "_" equal to T. Else the returned structure is void.

A typical utilization is a template definition that is configured according to a specific support as in the example below. If the type contains a function "f" (without argument) it is called. Else it is not.

template <class T>
meta::enable_if<meta::is_supported<T, has_f> >::_ void call(T& x) { x.f(); }
 
template <class T>
meta::enable_if<!meta::is_supported<T, has_f> >::_ void call(T& x) { }

Parameters

B	Condition.
T	Type (default to void).

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The documentation for this struct was generated from the following file:

• include/elm/meta.h