When PHP tries to imitate C

Gibou · 11-27-2007, 08:38 AM

Hi !

I have been impressed by this topic where Wildhoney gives a fantastic use of the __call magic method and it gave me the idea to propose mine. Don't hesitate to criticize :)

If someone here knows the C development, you have certainly heard about va_list. it's this kind of functions which can take as many parameters as you want.

For instance, in C, the first function you learn (printf) is a va_list. Indeed, you can give to it a string and after, as many parameters you have defined in the first string.

The prototype of a such function is : "int printf (const char *format, ...);"

The goal is to do the same in PHP with __call

For instance, an easy example, you want to do this kind of operation :

PHP Code:


			
$op->add(1,2,3);

// but too :

$op->add(1,2,3,4,5,6);

To do that, you have to declare two differents method or to give an array of values in parameter and it's not very easy to read.

I propose this (in a class "Operation")

PHP Code:


			
public function __call($method, $args = null)

{

    if($args)

    {

        // Initiation of the allowed methods

        $possibleOps = Array(

        "add" =>

        Array("method" => "addition", "init" => 0),

        "sub" =>

        Array("method" => "substract", "init" => $args[0]*2),

        "mul" =>

        Array("method" => "multiplicate", "init" => 1),

        "div" =>

        Array("method" => "divide", "init" => pow($args[0],2))

        );



        // If the called method is allowed...

        if(in_array($method,$possibleOps) && sizeof($args) >= 2)

        {

            // Selection of the method

            $tools = $possibleOps($method);

            // Initiation of the temporary value

            $tmp = $tools["init"];

            // Operations

            foreach($args as $val)

                $tmp = $this->$tools["method"]($tmp,$val);

            unset($tools);

            unset($possibleOps);

            return($tmp);

        }

        else

            return "Method not allowed";

    }

}



// Tests

$op = new Operation();

echo $op->add(1,2,3,4,5)."<br />";

echo $op->sub(5,4)."<br />";

echo $op->mul(2,5,3)."<br />";

echo $op->div(40,4,5);

Perhaps a little too heavy.
I confess I haven't tested it yet. Like we say in french, "à vue de nez, c'est bon" :D

What do you think of the concept ? I ask myself if the regulars accesses to the private methods don't burden the code in ram.

sjaq · 11-27-2007, 03:26 PM

func_get_args(); would also solve this problem and looks a lot less messy. (My first post by the way! :) )

Gibou · 11-27-2007, 03:34 PM

Indeed, thank you, I didn't know this function :)

Wildhoney · 11-27-2007, 03:50 PM

It's an interesting class. Incidentally, welcome to the community Sjag! However, func_get_args wouldn't cut it here because I think Gibou intended it to be so he can call the function for what it is. Instead of:

php Code:

$pObject->maths('add', 5, 10);

You could do:

php Code:

$pObject->add(5, 10);

I've come with a much more condensed function - still using the unsurpassed power of the magic method, __call! Here it is - based on Gibou's function:

php Code:

class Maths
{
    public function __call($szMethod, $aArgs)
    {
        $iTotal = $aArgs[0];
        unset($aArgs[0]);
        
        switch($szMethod)
        {
            case('add'): foreach($aArgs as $iValue) $iTotal += $iValue; break;
            case('minus'): foreach($aArgs as $iValue) $iTotal -= $iValue; break;
            case('divide'): foreach($aArgs as $iValue) $iTotal /= $iValue; break;
            case('multiply'): foreach($aArgs as $iValue) $iTotal *= $iValue; break;
        }
        
        return $iTotal;
    }
}

You can then use it like so:

php Code:

$pM = new Maths();
var_dump($pM->add(7, 10, 5, 2));

Which would add 10 to 7, 5 to 17, and 2 to 22, totalling 24. You can also do more complex things such as:

php Code:

var_dump($pM->multiply(5, 10, 2));

Which multiplies 10 by 5, to give us 50, then 50 by 2 to give us 100! I'm quite proud of this as I've never been any good at maths :( !

sketchMedia · 11-27-2007, 05:43 PM

another interesting topic containing __call().
Welcome to talkphp guys.

Gibou · 11-27-2007, 11:19 PM

Wildhoney > Indeed, that was the aim of this method : a clear way to do some similar operations.

sketchMedia > Thank you for the welcome. I have already read this topic but I think it won't be useless for me to re-read it.