std::mem_fn

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Utilità libreria

Tipo di supporto (basic types, RTTI, type traits)

Gestione della memoria dinamica

La gestione degli errori

Programma di utilità

Funzioni variadic

Data e ora

Funzione oggetti

initializer_list (C++11)

bitset

hash (C++11)

Gli operatori relazionali Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

Coppie e tuple Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Swap, in avanti e spostare Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Funzione oggetti

Funzione wrapper Original: Function wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
function (C++11)
mem_fn (C++11)
bad_function_call (C++11)
Associare Original: Bind The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
bind (C++11)
is_bind_expression (C++11)
is_placeholder (C++11)
_1, _2, _3, ... (C++11)
Wrapper di riferimento Original: Reference wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
reference_wrapper (C++11)
ref cref (C++11) (C++11)
Operatore wrapper Original: Operator wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
plus minus negate multiplies divides modulus logical_and logical_or logical_not	equal_to not_equal_to greater less greater_equal less_equal bit_and bit_or bit_xor
Negatori Original: Negators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
unary_negate binary_negate	not1 not2
Sconsigliata a leganti e adattatori Original: Deprecated binders and adaptors The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
unary_function (deprecato)
binary_function (deprecato)
ptr_fun (deprecato)
pointer_to_unary_function (deprecato)
pointer_to_binary_function (deprecato)
mem_fun (deprecato)
mem_fun_t mem_fun1_t const_mem_fun_t const_mem_fun1_t (deprecato) (deprecato) (deprecato) (deprecato)
mem_fun_ref (deprecato)
mem_fun_ref_t mem_fun1_ref_t const_mem_fun_ref_t const_mem_fun1_ref_t (deprecato) (deprecato) (deprecato) (deprecato)
binder1st binder2nd (deprecato) (deprecato)
bind1st bind2nd (deprecato) (deprecato)

 

Elemento definito nell'header <functional>
template<class R, class T > /*unspecified*/ mem_fn(R T::* pm);	(1)	(dal C++11)
template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)const); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)volatile); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)constvolatile); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)const&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)volatile&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)constvolatile&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)&&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)const&&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)volatile&&); template<class R, class T, class... Args> /*unspecified*/ mem_fn(R (T::* pm)(Args...)constvolatile&&);	(2)	(c + 11, ma difetto)

Modello std::mem_fn funzione genera oggetti wrapper per i puntatori ai membri, in grado di memorizzare, copiare, e richiamare un puntatore a membro. Entrambi i riferimenti e puntatori (compresi i puntatori intelligenti) a un oggetto può essere utilizzato quando si invoca un std::mem_fn.

Original:

Function template std::mem_fn generates wrapper objects for pointers to members, which can store, copy, and invoke a pointer to member. Both references and pointers (including smart pointers) to an object can be used when invoking a std::mem_fn.

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Gli overload (2) sono riportati come difetto.

Original:

The overloads (2) are reported as defect.

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Il resolution, che recentemente è stato votato "Timidamente Ready" si propone di rimuovere tutti i sovraccarichi (2).

Original:

The resolution, which has recently been voted "Tentatively Ready" proposes to remove all the overloads (2).

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Questo si rompe un po 'di codice, vedere Esempio 3.

Original:

This will break some code, see Example 3.

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Parametri

pm

-

puntatore al membro che verrà avvolto Original: pointer to member that will be wrapped The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valore di ritorno

std::mem_fn restituisce una fascia chiamata di tipo non specificato, che ha i seguenti membri:

Original:

std::mem_fn returns an call wrapper of unspecified type that has the following members:

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std :: mem_fn

Original:

std::mem_fn

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Return type

Member types

tipo Original: type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	definition
result_type	il tipo di ritorno di pm se pm è un puntatore a funzione membro, non definito per puntatore a oggetto membro Original: the return type of pm if pm is a pointer to member function, not defined for pointer to member object The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
argument_type	T*, possibilmente cv-qualificata, se pm è un puntatore a funzione membro prendere senza argomenti Original: T*, possibly cv-qualified, if pm is a pointer to member function taking no arguments The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
first_argument_type	T* se pm è un puntatore a funzione membro prendere un argomento Original: T* if pm is a pointer to member function taking one argument The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
second_argument_type	T1 se pm è un puntatore a funzione membro di prendere un argomento di T1 tipo Original: T1 if pm is a pointer to member function taking one argument of type T1 The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Member function

operator()	invoca l'obiettivo su un oggetto specificato, con i parametri opzionali Original: invokes the target on a specified object, with optional parameters The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)

Eccezioni

Nessuno.

Original:

None.

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Esempio 1

Utilizzare mem_fn per memorizzare ed eseguire una funzione di membro e un oggetto membro:

Original:

Use mem_fn to store and execute a member function and a member object:

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#include <functional>#include <iostream>   struct Foo {void display_greeting(){std::cout<<"Hello, world.\n";}void display_number(int i){std::cout<<"number: "<< i <<'\n';}int data =7;};   int main(){ Foo f;   auto greet = std::mem_fn(&Foo::display_greeting); greet(f);   auto print_num = std::mem_fn(&Foo::display_number); print_num(f, 42);   auto access_data = std::mem_fn(&Foo::data);std::cout<<"data: "<< access_data(f)<<'\n';}

Output:

Hello, world. number: 42 data: 7

Esempio 2

Passare una funzione membro per std::transform per creare una sequenza di numeri:

Original:

Pass a member function to std::transform to create a sequence of numbers:

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#include <iostream>#include <functional>#include <iterator>#include <memory>#include <string>#include <vector>#include <algorithm>   int main(){std::vector<std::string> words ={"This", "is", "a", "test"};std::vector<std::unique_ptr<std::string>> words2; words2.emplace_back(new std::string("another")); words2.emplace_back(new std::string("test"));   std::vector<std::size_t> lengths;std::transform(words.begin(), words.end(), std::back_inserter(lengths), std::mem_fn(&std::string::size));// uses references to stringsstd::transform(words2.begin(), words2.end(), std::back_inserter(lengths), std::mem_fn(&std::string::size));// uses unique_ptr to strings   std::cout<<"The string lengths are ";for(auto n : lengths)std::cout<< n <<' ';std::cout<<'\n';}

Output:

The string lengths are 4 2 1 4 7 4

Esempio 3

#include <functional>   struct X {int x;   int& easy(){return x;}int& get(){return x;}constint& get()const{return x;}};     int main(void){auto a = std::mem_fn(&X::easy);// no problem at all// auto b = std::mem_fn<int& >(&X::get ); // no longer works with new specificationauto c = std::mem_fn<int&()>(&X::get);// works with both old and new specificationauto d =[](X& x){return x.get();};// another approach to overload resolution}

Vedi anche

function (C++11)	avvolge oggetto invocabile di qualsiasi tipo con la firma specificato chiamata di funzione Original: wraps callable object of any type with specified function call signature The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe template)
bind (C++11)	lega uno o più argomenti a un oggetto funzione Original: binds one or more arguments to a function object The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)