Class templates for type decomposition

result_type

template<typename F>
struct result_type;

Header

#include <boost/function_types/result_type.hpp>

F: Type to analyze
result_type<F>::type: Result type of F

Extracts the result type of a callable, builtin type.

If F is no callable, builtin type, any attempt to access the type member results in a compile error.

parameter_types

template<typename F, class ClassTransform = add_reference<_> >
struct parameter_types;

Header

#include <boost/function_types/parameter_types.hpp>

F: Type to analyze
ClassTransform: MPL - Lambda Expression to transform the class type if F is a member function pointer
parameter_types<F,ClassTransform>: MPL - Front / Back Extensible Random Access Sequence of parameter types

Extracts the parameter types of a callable, builtin type.

If F is no callable, builtin type, any attempt to access the sequence results in a compile error.

function_arity

template<typename F>
struct function_arity;

Header

#include <boost/function_types/function_arity.hpp>

F: Callable builtin type
function_arity<F>: Function arity as MPL - Integral Constant
function_arity<F>::value: Constant value of the function arity

Extracts the function arity, that is the number of parameters. The hidden this of member function pointers counts, in other words the arity value is always greater than or equal to one if F is a member function pointer.

If F is no callable, builtin type, any attempt to access the value results in a compile error.

components

template<typename T, class ClassTransform = add_reference<_> >
struct components;

Header

#include <boost/function_types/components.hpp>

T: Type to analyze
ClassTransform: MPL - Lambda Expression to transform the class type if T is a member function pointer
components<T,ClassTransform>: MPL - Front / Back Extensible Random Access Sequence of all component types and property tag
components<T,ClassTransform>::types: Decorated MPL Sequence, exposed for optimization

Extracts all properties of a callable builtin type, that is the result type, followed by the parameter types (including the type of this for member function pointers).

If T is no callable builtin type, the component types are an empty sequence and the Tag's meaning is equivalent to the null_tag.

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