Specifying not-yet-defined arguments to dynamic calls in PHP

Question

I'm using PHP and the call_user_func_array function to make dynamic calls. I create an array of function names with their corresponding arguments which then get executed in a loop. e.g.:

$methods = [
    [ 'myfunction1', [$arg1, $arg2] ],
    [ 'myfunction2', [$arg3, $arg4] ],
];

foreach ($methods as $method) {
    call_user_func_array($method[0],$method[1]);
}

Whilst this works fine, the problem I'm facing is that at the moment I define the $methods array, some of the arguments have not been defined yet (e.g. $arg1,$arg4 have, $arg2 and $arg3 haven't) BUT they are defined by the time the function is called.

Therefore I'm looking for a way to tell the function where to find the value for that argument. So far what I've come up with is to replace the variable with a string representing the name of the variable:

$methods = [
     [ 'myfunction1', [$arg1, 'ARG2'] ],
     [ 'myfunction2', ['ARG3', $arg4] ],
];

Then in the foreach loop, I go through each argument, check if it is a string and it that string matches a variable I replace the string with the value of that variable:

foreach ($methods as $method) {
    foreach ($method[1] as $k => $arg) {
        if (is_string($arg)) {
            $name = strtolower($arg);
            if (isset(${$name})) {
                $method[1][$k] = ${$name};
            }
        }
    }
    call_user_func_array($method[0], $method[1]);
}

While this works, I'm wondering whether there are other known approaches used in PHP, as it might help me improve my code.

Do you know of any other way I could define dynamical calls with some of the arguments not being set at the time of definition?

Answer 1

You could use an anonymous function as the unknown argument that returns the value of the argument when called. This is working code:

function myfunction($arg1, $arg2)
{
    echo "\nARGS: $arg1, $arg2";
}

$arg2func = function() {
    return 'foo';
};

$arg3func = function() {
    return 'bar';
};

$arg1 = 'baz';
$arg4 = 'chopchop';

$methods = [
    [ 'myfunction', [$arg1, $arg2func] ],
    [ 'myfunction', [$arg3func, $arg4] ],
];
foreach ($methods as $method) {
    foreach ($method[1] as $k => $arg) {
        if (is_callable($arg)) {
            $method[1][$k] = $arg();
        }
    }
    call_user_func_array($method[0], $method[1]);
}