Closure

Closures are anonymous functions: functions without a name. They are also supported by the eponymous Closure class.

They are close to the arrow-functions. They are also created with the ... operator, also known as the first class callable.

<?php

    $closure = function ($a) use ($b) {
        return $a + $b + 1;
    };
    print get_class($closure); // Closure

    $closure2 = strtolower(...);
    print get_class($closure2); // Closure

    $closure3 = fn($a, $b) => $a + $b;
    print get_class($closure3); // Closure

?>

Documentation

See also Closure Optimisation (8.6).

Related : static, Arrow Functions, Anonymous Function, First Class Callable, Callables, Callbacks, Anonymous Class, Closure Binding, Functions, Return, Sort, Use, Callable Arrays, Array Callback, Bind, Inherited Variable, Closure Class, Custom Function, Lexical Variable, Currying, Homoiconicity, Meta-object Protocol (MOP), Recursion