How to access variable from scope of parent function?

Question

I want my function to access an outside variable—from its parent function specifically. However, using the global keyword sets too broad a scope; I need to limit it. How do I get this code to spit out 'Level 2' instead of 'Level 1'? Do I have to make a class?

<?php
$a = "Level 1";

function first() {
    $a = "Level 2";

    function second() {
        global $a;
        echo $a.'<br />';
    }

    second();
}

first();
//outputs 'Level 1'
?>

Answer 1

Just for the sake of example, if I understand what you're trying to do, you could use a closure (PHP 5.3+), as "Closures may also inherit variables from the parent scope" with the use keyword.

$a = "Level 1";

function first() {
    $a = "Level 2";

    $func = function () use ($a) {
        echo $a.'<br />';
    };

    $func();
}

first();
// prints 'Level 2<br />'

Closures are most commonly used for callback functions. This may not be the best scenario to use one, however. As others have suggested, just because you can do something doesn't mean it's the best idea.