PHP Functional Programming Anonymous function
Example
An anonymous function is just a function that doesn't have a name.
// Anonymous function
function() {
return "Hello World!";
};
In PHP, an anonymous function is treated like an expression and for this reason, it should be ended with a semicolon ;.
An anonymous function should be assigned to a variable.
// Anonymous function assigned to a variable
$sayHello = function($name) {
return "Hello $name!";
};
print $sayHello('John'); // Hello John
Or it should be passed as parameter of another function.
$users = [
['name' => 'Alice', 'age' => 20],
['name' => 'Bobby', 'age' => 22],
['name' => 'Carol', 'age' => 17]
];
// Map function applying anonymous function
$userName = array_map(function($user) {
return $user['name'];
}, $users);
print_r($usersName); // ['Alice', 'Bobby', 'Carol']
Or even been returned from another function.
Self-executing anonymous functions:
// For PHP 7.x
(function () {
echo "Hello world!";
})();
// For PHP 5.x
call_user_func(function () {
echo "Hello world!";
});
Passing an argument into self-executing anonymous functions:
// For PHP 7.x
(function ($name) {
echo "Hello $name!";
})('John');
// For PHP 5.x
call_user_func(function ($name) {
echo "Hello $name!";
}, 'John');
