Closures

What it is

Closures are anonymous functions that can capture outer values.

When to use it

Pass callbacks or encapsulate a short local operation.

Syntax

$apply = function (int $value) use ($fee): int { return $value + $fee; };

Example

$fee = 50;
$apply = function (int $value) use ($fee): int {
    return $value + $fee;
};
echo $apply(1250);

Common mistakes

use captures by value unless & is specified; references can introduce unintended mutation.

Related topics