PROGRAMMING
Php
Closures
Allow the creation of functions which have no specified name. Also known as closures.
preg_match("/-([a-z])/", "Hello-world", $match);
echo $match[1]; // output w
echo preg_replace_callback('/-([a-z])/', function($match) {
return " " . strtoupper($match[1]);
}, 'Hello-world'); // outputs: Hello World
Declaration
Be aware of the ; after function declaration. Without it, the following code will output a Notice (Parse error syntax)
$a = function($var) {
$b = "Hello $var";
return $b;
}; // ; at the end
echo $a('World'); // outputs: Hello World
Callbacks
Anonymous functions are useful when using callback functions. Functions like array_filter or array_map do:
$data = array(0, 3, 10);
$data = array_filter ($data, function($x) {
return $x % 2 == 0; // even
});
var_dump($data); // 0 => 0 / 2 => 10
$data = array(0, 3, 10);
$data = array_map(function ($x) {
return $x*$x;
}, $data); // square
var_dump($data); // [0, 9, 100]
➥ Questions
