php - Why is my getter method to get a static value inside a function not working?

Question

I'm new to php, so I'm not sure if I can do this. I've a class which has a static variable which I'm periodically changing with the help of a static function like below. I'm reading the static variable through a getter method in another static function.

infi_file.php

class infi_file {
    private static $value = 1;

    static function run_infinite ($interval) {
        while (true) {
            print date("H:i:s") . " - " . infi_file::$value . "\n";
            sleep ($interval);
            infi_file::$value = infi_file::$value ^ 1;
        }
    }

    static function getMode () {
        return infi_file::$value;
    }
}

run_infi_file.php

require_once "infi_file.php";

infi_file::run_infinite (5);

get_value.php

require_once "infi_file.php";

print infi_file::getMode () . "\n";

So I'm running both run_infi_file.php and get_value.php files simultaeously on 2 different terminal tabs.

While the output for run_infi_file is something like this :

15:11:51 - 1
15:11:56 - 0
15:12:01 - 1
15:12:06 - 0
...

the output of get_value always seems to be 1, even when the value is changed by run_infinite function. I thought that since $value is a static variable the entire class has just one copy which's used by all functions in that class. Why is this not happening?

are you sure that `infi_file::$value = infi_file::$value ^ 1;` is correct syntax? `$var = $var ^ 1` works like `$var++`? — Patrick Manser, Mar 21 '17 at 10:12
yea, i guess it's bitwise xor, which is what i'm looking for — user3248186, Mar 21 '17 at 10:14
Create a singleton-patter for your infi_file-class. http://stackoverflow.com/questions/203336/creating-the-singleton-design-pattern-in-php5 — Oliver, Mar 21 '17 at 10:17
created a singleton pattern as you mentioned, still no change. — user3248186, Mar 21 '17 at 11:12
as per @PatrickManser 's comment, if bitwise xor is what you are looking for, you are getting what you are looking for. 1^1 => 0, and 0^1 => 1. This is not about 'static variable access'. Change your ^ to a + — YvesLeBorg, Mar 21 '17 at 12:19
yea, the problem is with the 2nd output - get_value.php - it's always printing 1, irrespective of the values printed by run_infi_file.php — user3248186, Mar 21 '17 at 12:22

score 0 · Answer 1 · answered Mar 21 '17 at 10:09

0

You should use self for referring to static vars inside the class

    static function getMode () {
    return self::$value;
}

answered Mar 21 '17 at 10:09

ScaisEdge

131,976
10
91
107

I changed it to self, still no change – user3248186 Mar 21 '17 at 10:16
You would have to change `infi_file::$value;` also in your `run_infinite` method! – Patrick Manser Mar 21 '17 at 10:38
yes .. in .run_infinite too .. .if you refer to an internal var in a class inside a function you should use self. – ScaisEdge Mar 21 '17 at 10:40
changed to self in all references inside the class – user3248186 Mar 21 '17 at 10:50

score 0 · Answer 2 · answered Mar 21 '17 at 10:25

0

A static function will not know of the other static methods and how they have affected variables AFAIK.

answered Mar 21 '17 at 10:25

Ryan Hipkiss

648
1
7
20

php - Why is my getter method to get a static value inside a function not working?

2 Answers2