boost::proto::is_callable< T > Struct Template Reference

Boolean metafunction which detects whether a type is a callable function object type or not. More...

#include <traits.hpp>

Inheritance diagram for boost::proto::is_callable< T >:

Collaboration diagram for boost::proto::is_callable< T >:

Detailed Description

template<typename T>
struct boost::proto::is_callable< T >

Boolean metafunction which detects whether a type is a callable function object type or not.

is_callable<> is used by the when<> transform to determine whether a function type R(A1,A2,...AN) is a callable transform or an object transform. (The former are evaluated using call<> and the later with make<>.) If is_callable<R>value is true, the function type is a callable transform; otherwise, it is an object transform.

Unless specialized for a type T, is_callable<T>value is computed as follows:

• If T is a template type X<Y0,Y1,...YN>, where all Yx are types for x in [0,N], is_callable<T>value is is_same<YN, proto::callable>value.
• If T has a nested type proto_is_callable_ that is a typedef for void, is_callable<T>value is true. (Note: this is the case for any type that derives from proto::callable.)
• Otherwise, is_callable<T>value is false.

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

• boost_1_57_0/boost/proto/proto_fwd.hpp