Static variables in a class

[php_guy]

Hello!

 

How could I have a static member variable inside a class?

// common.php
class my_class 
{
    $flag = true;
}

So that later, I can use it in the following manner:

 

// some other file

require_once("common.php");

if( my_class::flag == true ) {
}

 

Thanks!

 

[per1os]

It depends if you are using php 5 it should look something like this:

 

<?php
class my_class 
{
    public $flag = true;
}

 

or php 4

 

<?php
class my_class 
{
    var $flag;

    function my_class() {
          $this->flag = true; // instantiate the variable
    }
}

[trq]

<?php

  class foo {
    static $bar = true;
  }

  if (foo::$bar) {
    echo "true";
  }

?>

[php_guy]

Thanks guys! 

[roopurt18]

Consider taking it one step further and using a static function in combination with a static variable:

 

<?php
  class foo {
    static $bar = true;

    public static function performTest(){
      return foo::$bar;
    }
  }

  if (foo::performTest()) {
    echo "true";
  }
?>

 

The benefit is not apparent until you decide that a simple flag is not enough to determine the condition.  In the future, you may have to compare $bar with multiple values or perform additional logical operations.  Should that occur, you will have to go through all of your code and update your conditionals that are testing the value foo::$bar.

 

However, if you wrap the test inside of a static method and later decide to change the test, you only have to change it in one place and all of your code will continue to work.