The __invoke() magic method gets triggered when the object is being called as a function. The method accepts an optional number of parameters and is is able to return various types of data, or no data at all, as per the following synopsis:
mixed __invoke([ $... ])
If an object class implements the __invoke() method, we can call the method by specifying parentheses () right after the object's name. This type of object is known as a functor or function object.
Note
The Wikipedia page (https://en.wikipedia.org/wiki/Functor) provides more information on the functor.
The following block of code illustrates the simple __invoke() implementation:
<?php
class User
{
public function __invoke($name, $age)
{
echo $name . ', ' . $age;
}
}The __invoke() method can be triggered either by using the object instance as a function or by calling call_user_func(),
$user = new User();
$user('John', 34); // outputs: John, 34
call_user_func($user, 'John', 34); // outputs: John, 34Using...