const_mem_fun_t Class

Article
01/02/2018

The latest version of this topic can be found at const_mem_fun_t Class.

An adapter class that allows a const member function that takes no arguments to be called as a unary function object when initialized with a reference argument.

Syntax

template <class Result, class Type>
class const_mem_fun_t : public unary_function <Type *, Result>  
{
    explicit const_mem_fun_t(Result (Type::* _Pm)() const);

    Result operator()(
    const Type* _Pleft) const;

 };

Parameters

_Pm
A pointer to the member function of class Type to be converted to a function object.

_Pleft
The object that the _Pm member function is called on.

Return Value

An adaptable unary function.

Remarks

The template class stores a copy of _Pm, which must be a pointer to a member function of class Type, in a private member object. It defines its member function operator() as returning ( _Pleft->* _Pm)() const.

Example

The constructor of const_mem_fun_t is not usually used directly; the helper function mem_fun is used to adapt member functions. See mem_fun for an example of how to use member function adaptors.

Requirements

Header: <functional>

Namespace: std