Is static method faster than non-static?

Question

EDIT::oh i forgot

class Test1{
    public static function test(){
        for($i=0; $i<=1000; $i++)
            $j += $i;       
    }   
}

class Test2{
    public function test() {
        for ($i=0; $i<=1000; $i++){
            $j += $i;
        }
    }

}

for this algorithm

$time_start = microtime();
$test1 = new Test2();
for($i=0; $i<=100;$i++)
    $test1->test();
$time_end = microtime();

$time1 = $time_end - $time_start;

$time_start = microtime();
for($i=0; $i<=100;$i++)
    Test1::test();
$time_end = microtime();    

$time2 = $time_end - $time_start;
$time = $time1 - $time2;
echo "Difference: $time";

i have results

Difference: 0.007561 

and these days, i am trying to make my methods static as possible. But is it really true, .. atleast for php

Answer 1

You should always use static when you don't need an object around you method, and use dynamic when you need an object. In the example you provides, you don't need an object, because the method doesn't interact with any properties or fields in your class.

This one should be static, because it doesn't need an object:

class Person {
    public static function GetPersonByID($id) {
        //run SQL query here
        $res = new Person();
        $res->name = $sql["name"];
        //fill in the object
        return $res;
    }
}

This one should be dynamic, because it uses the object it is in:

class Person {
    public $Name;
    public $Age;
    public function HaveBirthday() {
        $Age++;
    }
}

The speed diffirence is minimal, but you have to create an object to run dynamic methods, and that object is saved in memory, so dynamic methods use more memory and a little more time.

Answer 2

Short Answer since I don't want to go on a rant to much:

It doesn't matter if it's faster. If you need something where performance is THAT important that you think about shaving of 0.02 nanoseconds per function call than you're not going to do it in PHP anyways.

Static methods make for untestable, unmaintainable, "global everything" code that is going to hurt you much more than anything else.

If you don't want to use proper OOP (and thats totally fine if you know what and why you are doing it) then please do so. Just don't do it because you want to save cpu time.

http://misko.hevery.com/2008/12/15/static-methods-are-death-to-testability/

http://sebastian-bergmann.de/archives/885-Stubbing-Hard-Coded-Dependencies.html

http://en.wikipedia.org/wiki/Class-based_programming

If you only click one link: http://www.scribd.com/doc/20893084/Advanced-OOP-and-Design-Patterns#scribd

Premature optimization is the root of all evil. Build code that is easy to maintain and if it's getting slow take a profile and it will most likely tell you that the filesystem oder the database is problem, one you got all that sorted out there will be some very specific pieces of php to optimize. If you got clean, changeable code you can speed those up.