php static function

Question

I have a question regarding static function in php.

let's assume that I have a class

class test {
    public function sayHi() {
        echo 'hi';
    }
}

if I do test::sayHi(); it works without a problem.

class test {
    public static function sayHi() {
        echo 'hi';
    }
}

test::sayHi(); works as well.

What are the differences between first class and second class?

What is special about a static function?

As of php7 you cannot call non static method statically – sanjay yadav Feb 15 '16 at 04:47 — sanjay yadav, Feb 15 '16 at 04:47

score 157 · Accepted Answer · edited Dec 20 '14 at 03:01

157

In the first class, sayHi() is actually an instance method which you are calling as a static method and you get away with it because sayHi() never refers to $this.

Static functions are associated with the class, not an instance of the class. As such, $this is not available from a static context ($this isn't pointing to any object).

edited Dec 20 '14 at 03:01

Makyen

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answered May 24 '09 at 02:20

Jonathan Fingland

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Now static calling of non-static methods works but is deprecated. Be careful using this syntax for instance methods! – Jet May 24 '09 at 12:52
1

So this why they say it as static function? because there is no multiple instance with dynamic data flow and dynamic output. Just guide me.@chaos – sun Feb 25 '14 at 13:50

score 22 · Answer 2 · edited Oct 12 '18 at 21:13

22

Simply, static functions function independently of the class where they belong.

$this means, this is an object of this class. It does not apply to static functions.

class test {
    public function sayHi($hi = "Hi") {
        $this->hi = $hi;
        return $this->hi;
    }
}
class test1 {
    public static function sayHi($hi) {
        $hi = "Hi";
        return $hi;
    }
}

//  Test
$mytest = new test();
print $mytest->sayHi('hello');  // returns 'hello'
print test1::sayHi('hello');    //  returns 'Hi'

edited Oct 12 '18 at 21:13

Lucas Bustamante

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answered Aug 27 '13 at 15:36

user2132859

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Ok I'm not a PHP wizard, but isn't the variable ('hello') that is passed to the static function, explicitly being overwritten with 'Hi'? Meaning that the line print test1::sayHi('hello'); would not return 'hello', but would return 'hi'? – Fnord23 Nov 12 '15 at 22:27
7

This answer is sloppy (the effect of static functions *can* depend on which class they're in) and the examples don't make the point very clear. – reinierpost May 17 '16 at 22:00
Not a very good example. $hi = 'Hi'; overwrites the given argument, and has nothing to do with static declaration. I would fix this like: self::$hi = $hi; and it would work just like the non-static one. You can access the class variables with self:: instead of $this-> – GotBatteries Apr 07 '20 at 06:51

score 20 · Answer 3 · answered May 24 '09 at 02:15

20

Entire difference is, you don't get $this supplied inside the static function. If you try to use $this, you'll get a Fatal error: Using $this when not in object context.

Well, okay, one other difference: an E_STRICT warning is generated by your first example.

answered May 24 '09 at 02:15

chaos

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i have no warning when i use first and i'm in php7 – TechDogLover OR kiaNasirzadeh Aug 22 '18 at 12:04
Why don't we have $this inside a static function? What's the architectural logic of this? Thanks. – Lucas Bustamante Oct 12 '18 at 21:14
1

@LucasBustamante: `$this` refers to the current object. In a static function, there is no current object; the function exists on the class without need for or reference to an object instance of that class. – chaos Oct 15 '18 at 18:20

score 4 · Answer 4 · answered Sep 02 '14 at 18:40

4

Calling non-static methods statically generates an E_STRICT level warning.

answered Sep 02 '14 at 18:40

score 2 · Answer 5 · answered May 24 '09 at 02:17

2

In a nutshell, you don't have the object as $this in the second case, as the static method is a function/method of the class not the object instance.

answered May 24 '09 at 02:17

Czimi

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is static simply how you define class functions? no other fancy business? So you're saying if it had been called "class_method" rather than "static", it would be more semantic? – ahnbizcad May 10 '15 at 06:31

score 1 · Answer 6 · edited Dec 30 '11 at 08:08

1

After trying examples (PHP 5.3.5), I found that in both cases of defining functions you can't use $this operator to work on class functions. So I couldn't find a difference in them yet. :(

edited Dec 30 '11 at 08:08

Cosmin

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answered Dec 30 '11 at 07:52

yogesh

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php static function

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