Best way to give a variable a default value (simulate Perl ||, ||= )

Question

I love doing this sort of thing in Perl: $foo = $bar || $baz to assign $baz to $foo if $bar is empty or undefined. You al

Answer 1

Thanks for all the great answers!

For anyone else coming here for a possible alternative, here are some functions that help take the tedium out of this sort of thing.

function set_if_defined(&$var, $test){
    if (isset($test)){
        $var = $test;
        return true;
    } else {
        return false;
    }
}

function set_unless_defined(&$var, $default_var){
    if (! isset($var)){
        $var = $default_var;
        return true;
    } else {
        return false;
    }
}

function select_defined(){
    $l = func_num_args();
    $a = func_get_args();
    for ($i=0; $i<$l; $i++){
        if ($a[$i]) return $a[$i];
    }
}

Examples:

// $foo ||= $bar;
set_unless_defined($foo, $bar);

//$foo = $baz || $bletch
$foo = select_defined($baz, $bletch);

I'm sure these can be improved upon.