Editing Function object (section)

== In PHP ==

[[PHP]] 5.3+ has [[first-class function]]s that can be used e.g. as parameter to the {{Code|usort()}} function:

<syntaxhighlight lang="php">
$a = array(3, 1, 4);
usort($a, function ($x, $y) { return $x - $y; });
</syntaxhighlight>

[[PHP]] 5.3+, supports also lambda functions and closures.

<syntaxhighlight lang="php">
function Accumulator($start)
{
    $current = $start;
    return function($x) use(&$current)
    {
        return $current += $x;
    };
}
</syntaxhighlight>

An example of this in use:

<syntaxhighlight lang="php">
$a = Accumulator(4);
$x = $a(5);
echo "x = $x<br/>";	// x = 9
$x = $a(2);
echo "x = $x<br/>";	// x = 11
</syntaxhighlight>

It is also possible in PHP 5.3+ to make objects invokable by adding a magic {{Code|__invoke()}} method to their class:<ref name="phpinvoke">[http://php.net/manual/en/language.oop5.magic.php#object.invoke PHP Documentation on Magic Methods]</ref>

<syntaxhighlight lang="php">
class Minus
{
    public function __invoke($x, $y)
    {
        return $x - $y;
    }
}

$a = array(3, 1, 4);
usort($a, new Minus());
</syntaxhighlight>