PHP Design Patterns PHP OO Static Basics

PHP Static Basics

Here are examples of creating and using static variables and function in a class.

The static variable $red is called by the function getStaticVarRed() and the static function staticGetStaticVarRed(), as well as directly by testOOPHPStatic.

Note that within it's own class a static variable or funtion should be referenced by self::variable or self::function(), instead of using this->. In an other class a static should be referenced byt the full name of the class with a double colon and the name of the variable or function, such as classname::$varname or classname::functioname().

OOPHPStatic.php

//copyright Lawrence Truett and FluffyCat.com 2007, all rights reserved


  //OOPHPStatic - a simple OO PHP Class with 
  //                         a static variable and function
  
  class OOPHPStatic {
    
    //a static variable, 
    static $red = 'RED';  
    
    public function getStaticVarRed() {
      return self::$red;
    }  


    public static function staticGetStaticVarRed() {
      return self::$red;
    }    
  
  }

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testOOPHPStatic.php

//copyright Lawrence Truett and FluffyCat.com 2007, all rights reserved


  include_once('OOPHPStatic.php');


  define('BR', '<'.'BR'.'>');


  echo 'TESTING OOPHPStatic'.BR;
  echo BR;
  
  echo 'test 1 - show the static var directly'.BR;
  echo 'red: '.OOPHPStatic::$red;
  echo BR.BR;


  echo 'test 2 - show the static var using a class instance'.BR;
  $classOne = new OOPHPStatic();
  echo 'red: '.$classOne->getStaticVarRed();
  echo BR.BR;


  echo 'test 3 - show the static var using a static function'.BR;
  echo 'red: '.OOPHPStatic::staticGetStaticVarRed();
  echo BR.BR;


  echo 'END TESTING OOPHPStatic'.BR;

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output of testOOPHPStatic.php

TESTING OOPHPStatic


test 1 - show the static var directly
red: RED


test 2 - show the static var using a class instance
red: RED


test 3 - show the static var using a static function
red: RED


END TESTING OOPHPStatic

References

Design Patterns
Design Patterns by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides

PHP 5
The Official PHP web site
Core PHP Programming, 3rd Edition by Leon Atkinson and Zeev Suraski