std::function - cppreference.com

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Elemento definito nell'header `<functional>`

`template< class > class function; /* undefined */`		(dal C++11)

`template< class R, class... Args > class function<R(Args...)>`		(dal C++11)

Modello std::function classe è un general-purpose wrapper di funzione polimorfa. Le istanze di std::function in grado di memorizzare, copiare, e richiamare qualsiasi callable bersaglio - funzioni, lambda espressioni, bind espressioni, o altri oggetti funzione.

Original:

Class template std::function is a general-purpose polymorphic function wrapper. Instances of std::function can store, copy, and invoke any callable target -- functions, lambda espressioni, bind espressioni, or other function objects.

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Membri tipi


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`	`R`

`argument_type`	`T` se `sizeof...(Args)==1` e `T` è il primo tipo e solo in `Args...` Original: `T` if `sizeof...(Args)==1` and `T` is the first and only type in `Args...` 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`	`T1` se `sizeof...(Args)==2` `T1` ed è il primo dei due tipi di `Args...` Original: `T1` if `sizeof...(Args)==2` and `T1` is the first of the two types in `Args...` 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`	`T2` se `sizeof...(Args)==2` e `T2` è il secondo dei due tipi di `Args...` Original: `T2` if `sizeof...(Args)==2` and `T2` is the second of the two types in `Args...` The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Membri funzioni


(costruttore)	costruisce una nuova istanza std::function Original: constructs a new std::function instance The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

(destructor)	distrugge un'istanza std::function Original: destroys a std::function instance The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

operator=	assegna il contenuto Original: assigns the contents The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

swap	swap il contenuto Original: swaps the contents The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

assign	assegna un nuovo obiettivo Original: assigns a new target The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

operator bool	Verifica se un bersaglio valido è contenuto Original: checks if a valid target is contained The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

operator()	invoca il bersaglio Original: invokes the target The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]
Mirate accesso Original: Target access The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

target_type	ottiene il `typeid` del target memorizzato di un std::function Original: obtains the `typeid` of the stored target of a std::function The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

target	ottiene un puntatore al target memorizzato di un std::function Original: obtains a pointer to the stored target of a std::function The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) [modifica]

Non membri funzioni


	specializzata l'algoritmo std::swap Original: specializes the std::swap algorithm 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) [modifica]

	confronta con un std::function `std::nullptr` Original: compares an std::function with `std::nullptr` 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)

Helper classi


	specializzata il tratto tipo std::uses_allocator Original: specializes the std::uses_allocator type trait The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe modello di specializzazione) [modifica]

Esempio

#include <functional>
#include <iostream>

struct Foo {
    Foo(int num) : num_(num) {}
    void print_add(int i) const { std::cout << num_+i << '\n'; }
    int num_;
};

void print_num(int i)
{
    std::cout << i << '\n';
}

int main()
{
    // store a free function
    std::function<void(int)> f_display = print_num;
    f_display(-9);

    // store a lambda
    std::function<void()> f_display_42 = []() { print_num(42); };
    f_display_42();

    // store the result of a call to std::bind
    std::function<void()> f_display_31337 = std::bind(print_num, 31337);
    f_display_31337();

    // store a call to a member function
    std::function<void(const Foo&, int)> f_add_display = &Foo::print_add;
    Foo foo(314159);
    f_add_display(foo, 1);
}

Output:

Vedi anche


	l'eccezione generata quando si invoca un std::function vuoto Original: the exception thrown when invoking an empty std::function The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe) [modifica]

	crea un oggetto funzione di un puntatore a un membro Original: creates a function object out of a pointer to a member 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) [modifica]