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std::move_only_function:: operator bool

From cppreference.net
Utilities library
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
( until C++20* )
( until C++17* ) ( until C++17* )
( until C++17* ) ( until C++17* )

( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
( until C++20* )
explicit operator bool ( ) const noexcept ;
(desde C++23)

Comprueba si * this almacena un objetivo invocable, es decir, no está vacío.

Contenidos

Parámetros

(ninguno)

Valor de retorno

true si * this almacena un objetivo invocable, false en caso contrario.

Ejemplo

#include <functional>
#include <iostream>
void sampleFunction()
{
    std::cout << "This is the sample function!\n";
}
void checkFunc(std::move_only_function<void() const> const& func)
{
    // Use operator bool to determine if callable target is available.
    if (func)
    {
        std::cout << "Function is not empty! Calling function.\n";
        func();
    }
    else
        std::cout << "Function is empty. Nothing to do.\n";
}
int main()
{
    std::move_only_function<void() const> f1{};
    std::move_only_function<void() const> f2{sampleFunction};
    std::cout << "f1: ";
    checkFunc(f1);
    std::cout << "f2: ";
    checkFunc(f2);
}

Salida:

f1: Function is empty. Nothing to do.
f2: Function is not empty! Calling function.
This is the sample function!

Véase también

(C++23)
compara un std::move_only_function con nullptr
(función)
verifica si contiene un objetivo
(función miembro pública de std::function<R(Args...)> )