__invoke

Description

The __invoke() magic method is called when an object is used as a function. This allows objects to behave like callable functions while maintaining internal state.

This pattern is useful for creating configurable callbacks, middleware, single-action classes, and strategy patterns. Objects with __invoke() pass is_callable() checks and can be used anywhere a callable is expected.

The method can accept any number of parameters and return any type. It effectively turns a class into a functor, a common pattern in functional programming.

Arguments

Example

class Multiplier {
    public function __construct(private int $factor) {}

    public function __invoke(int $value): int {
        return $value * $this->factor;
    }
}

$double = new Multiplier(2);
echo $double(5);   // 10
echo $double(10);  // 20

$result = array_map($double, [1, 2, 3]);
// [2, 4, 6]

Reference

• Official Documentation