PHP pass function name as param then call the function?

In php this is very simple.

<?php

function here() {
  print 'here';
}


function dynamo($name) {
 $name();
}

//Will work
dynamo('here');
//Will fail
dynamo('not_here');

I know the original question asked about PHP 4.3, but now it's a few years later and I just wanted to advocate for my preferred way to do this in PHP 5.3 or higher.

PHP 5.3+ now includes support for anonymous functions (closures), so you can use some standard functional programming techniques, as in languages like JavaScript and Ruby (with a few caveats). Rewriting the call_user_func example above in "closure style" would look like this, which I find more elegant:

$barber = function($type) {
    echo "You wanted a $type haircut, no problem\n";
};

$barber('mushroom');
$barber('shave');

Obviously, this doesn't buy you much in this example - the power and flexibility comes when you pass these anonymous functions to other functions (as in the original question). So you can do something like:

$barber_cost = function($quantity) {
    return $quantity * 15;
};

$candy_shop_cost = function($quantity) {
    return $quantity * 4.50;   // It's Moonstruck chocolate, ok?
};

function get_cost($cost_fn, $quantity) {
    return $cost_fn($quantity);
}

echo '3 haircuts cost $' . get_cost($barber_cost, 3) . "\n";
echo '6 candies cost $' . get_cost($candy_shop_cost, 6) . "\n";

This could be done with call_user_func, of course, but I find this syntax much clearer, especially once namespaces and member variables get involved.

One caveat: I'll be the first to admit I don't know exactly what's going on here, but you can't always call a closure contained in a member or static variable, and possibly in some other cases. But reassigning it to a local variable will allow it to be invoked. So, for example, this will give you an error:

$some_value = \SomeNamespace\SomeClass::$closure($arg1, $arg2);

But this simple workaround fixes the issue:

$the_closure = \SomeNamespace\SomeClass::$closure;
$some_value = $the_closure($arg1, $arg2);

function foo($function) {
  $function(" World");
}
function bar($params) {
  echo "Hello".$params;
}

$variable = 'bar';
foo($variable);

Additionally, you can do it this way. See variable functions.

I think you are looking for call_user_func.

An example from the PHP Manual:

<?php
function barber($type) {
    echo "You wanted a $type haircut, no problem";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
?>