NAME¶

std::move_only_function::operatorbool - std::move_only_function::operatorbool

Synopsis¶

explicit operator bool() const noexcept; (since C++23)

Checks whether *this stores a callable target, i.e. is not empty.

Parameters¶

(none)

Return value¶

true if *this stores a callable target, false otherwise.

Example¶

// Run this code

#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);
}

Output:¶

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

See also¶

operator== compares a std::move_only_function with nullptr
(C++23) (function)
operator bool checks if a target is contained
(public member function of std::function<R(Args...)>)