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VMS Help CXXLSTD, Adaptors, mem_fun *Conan The Librarian |
Standard C++ Library
Copyright 1996, Rogue Wave Software, Inc.
NAME
mem_fun, mem_fun1, mem_fun_ref, mem_fun_ref1 - Function objects
that adapt a pointer to a member function to work where a
global function is called for.
SYNOPSIS
#include <functional>
template <class S, class T> class mem_fun_t;
template <class S, class T, class A> class mem_fun1_t;
template <class S, class T> class mem_fun_ref_t;
template <class S, class T, class A> class mem_fun1_ref_t;
template<class S, class T> mem_fun_t<S,T>
mem_fun(S, (T::*f)());
template<class S, class T, class A> mem_fun1_t<S,T,A>
mem_fun1(S, (T::*f)(A));
template<class S, class T> mem_fun_ref_t<S,T>
mem_fun_ref(S, (T::*f)());
template<class S, class T, class A> mem_fun1_ref_t<S,T,A>
mem_fun1_ref(S, (T::*f)(A));
DESCRIPTION
The mem_fun group of templates each encapsulates a pointer to a
member function. Each category of template (i.e. mem_fun, mem_fun1,
mem_fun_ref, or mem_fun1_ref) provides both a class template and a
function template, where the class is distinguished by the addition
of _t on the end of the name to identify it as a type.
The class's constructor takes a pointer to a member function, and
provides an operator() that forwards the call to that member
function. In this way the resulting object serves as a global
function object for that member function.
The accompanying function template simplifies the use of this
facility by constructing an instance of the class on the fly.
The library provides zero and one argument adaptors for containers
of pointers and containers of references (_ref). This
technique can be easily extended to include adaptors for two
argument functions, and so on.
INTERFACE
template <class S, class T> class mem_fun_t
: public unary_function<T*, S> {
public:
explicit mem_fun_t(S (T::*p)());
S operator()(T* p);
};
template <class S, class T, class A> class mem_fun1_t
: public binary_function<T*, A, S> {
public:
explicit mem_fun1_t(S (T::*p)(A));
S operator()(T* p, A x);
};
template<class S, class T> mem_fun_t<S,T>
mem_fun(S, (T::*f)());
template<class S, class T, class A> mem_fun1_t<S,T,A>
mem_fun1(S, (T::*f)(A));
template <class S, class T> class mem_fun_ref_t
: public unary_function<T, S> {
public:
explicit mem_fun_ref_t(S (T::*p)());
S operator()(T* p);
};
template <class S, class T, class A> class mem_fun1_ref_t
: public binary_function<T, A, S> {
public:
explicit mem_fun1_ref_t(S (T::*p)(A));
S operator()(T* p, A x);
};
template<class S, class T> mem_fun_ref_t<S,T>
mem_fun_ref(S, (T::*f)());
template<class S, class T, class A> mem_fun1_ref_t<S,T,A>
mem_fun1_ref(S, (T::*f)(A));
EXAMPLE
//
// mem_fun example
//
#include <functional>
#include <list>
int main(void)
{
int a1[] = {2,1,5,6,4};
int a2[] = {11,4,67,3,14};
list<int> s1(a1,a1+5);
list<int> s2(a2,a2+5);
// Build a list of lists
list<list<int>* > l;
l.insert(l.begin(),s1);
l.insert(l.begin(),s2);
// Sort each list in the list
for_each(l.begin(),l.end(),mem_fun(&list<int>::sort));
}
SEE ALSO
binary_function, function_objects, pointer_to_unary_function,
ptr_fun
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee
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