关闭重载：是否可以检查PHP闭包的参数数量而不执行它？

Question

What I want to do

I want to inspect a closure (passed as a variable) to determine how many arguments it expects. Essentially, I want to overload a closure in the traditional sense, only by treating it differently.

function someMethod(Closure $callback) {
    $varA;
    $varB;
    $varC;
    if($callback->getNumArgs() == 3) {
        $callback($varA, $varB, $varC);
    }
    else {
        $callback($varC, $varA);
    }
}

If this could be explained better, please let me know so it can be edited.

Background information

Depending on how many arguments the closure takes, I will adjust the way in which it's called. I need to do this to save expensive iterations through a loop.

Please note

• I am using PHP5.3
• As a reminder, I do not want to execute the function and thus cannot use func_num_args

Answer 1

With Reflection :

$ref = new ReflectionFunction(function($foo, $bar) {});
echo $ref->getNumberOfParameters(); // 2