RetroSearch Browse

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://en.cppreference.com/w/cpp/language/../utility/functional/move_only_function/operator().html below:

std::move_only_function::operator() - cppreference.com

R operator()( Args... args ) /*cv*/ /*ref*/ noexcept(/*noex*/);

(since C++23)

Invokes the stored callable target with the parameters args. The /*cv*/, /*ref*/, and /*noex*/ parts of operator() are identical to those of the template parameter of std::move_only_function.

Equivalent to return std::invoke_r<R>(/*cv-ref-cast*/(f), std::forward<Args>(args)...);, where f is a cv-unqualified lvalue that denotes the target object of *this, and /*cv-ref-cast*/(f) is equivalent to:

f if cv ref is either empty or &, or
std::as_const(f) if cv ref is either const or const &, or
std::move(f) if cv ref is &&, or
std::move(std::as_const(f)) if cv ref is const &&.

The behavior is undefined if *this is empty.

[edit] Parameters args - parameters to pass to the stored callable target [edit] Return value

std::invoke_r<R>(/*cv-ref-cast*/(f), std::forward<Args>(args)...).

[edit] Exceptions

Propagates the exception thrown by the underlying function call.

[edit] Example

The following example shows how std::move_only_function can passed to other functions by value. Also, it shows how std::move_only_function can store lambdas.

#include <iostream>
#include <functional>
 
void call(std::move_only_function<int() const> f)  // can be passed by value
{ 
    std::cout << f() << '\n';
}
 
int normal_function() 
{
    return 42;
}
 
int main()
{
    int n = 1;
    auto lambda = [&n](){ return n; };
    std::move_only_function<int() const> f = lambda;
    call(std::move(f));
 
    n = 2;
    call(lambda); 
 
    f = normal_function; 
    call(std::move(f));
}

Output:

[edit] See also invokes the target
(public member function of std::function<R(Args...)>) [edit] calls the stored function
(public member function of std::reference_wrapper<T>) [edit] invokes any Callable object with given arguments and possibility to specify return type(since C++23)
(function template) [edit]

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4