Question

I have this code:

function cmp_asc($a, $b){
    $ta = date_create_from_format('Y/m/d', $a['props']['t']); //  Y/n/j  si no tienen 0 inicial
    $tb = date_create_from_format('Y/m/d', $b['props']['t']);
    $interval = date_diff($ta, $tb);

    if($interval->days != 0){
        if($interval->invert == 1){
            return 1;
        }else{
            return -1;
        }
    }else{
        return 0;
    }
}

$arr1 = array(
    'props' => array('t' => '2012/05/20')
);

$arr2 = array(
    'props' => array('t' => '2012/05/21')
);

$arr3 = array(
    'props' => array('t' => '2012/04/14')
);

$arr = array($arr1, $arr2, $arr3);

uasort($arr, 'cmp_asc');

and I’d like to know if I can pass the ['props']['t'] via arguments.
So, it will end up like:

function cmp_asc($a, $b, $key){
    $ta = date_create_from_format('Y/m/d', $a <-- $key -->);
    ...
...

I’m thinking about variable variables, but I’m not too sure this is the right way to do it.
Any other ideas?

Answer 1

Not really as argument, because you’re not calling the function yourself, but you can use closures to pass other variables into the function:

$key1 = 'props';
$key2 = 't';

uasort($arr, function ($a, $b) use ($key1, $key2) {
    $ta = date_create_from_format('Y/m/d', $a[$key1][$key2]);
    ...
});

That’s just a simple example. If you need dynamic key depths, this’ll need a bit more code, along these lines:

function getValue(array $value, $key) {
    $keys = explode('.', $key);
    foreach ($keys as $k) {
        $value = $value[$k];
    }
    return $value;
}

$arr = array('foo' => array('bar' => 'baz'));
echo getValue($arr, 'foo.bar');

Another idea would be using a class, usage of which would look like this:

$cmp = new ComparisonClass;
$cmp->key = 'props.t';

uasort($arr, array($cmp, 'compare'));

I’ll let you figure out the implementation of ComparisonClass.

A nicer solution may be to simply standardize the format of the array you’re going to sort.