. PHP Design Patterns . PHP Design Patterns PHP OO This and Parent Basics

PHP Design Patterns PHP OO This and Parent Basics

PHP This and Parent Basics

Here are examples of using this and parent to call functions in a class. Using $this-> a class calls functions in itself, using parent:: a class calls functions in it's parent class.

If you are used to Java or other OO languages you might expect parent:: to be $super->, but with PHP it is not. Maybe super wasn't used to avoid confusion with superglobals. I don't know why :: is used instead of -> for non static calls.

OOPHPParentClass.php

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


  //OOPHPParentClass - a simple OO PHP Class which is extended by OOPHPChildClass
  
  class OOPHPParentClass {  
    
    public function getColor() {
      return 'RED';
    }


  }

download source, use right-click and "Save Target As..." to save with a .php extension.

OOPHPChildClass.php

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


  //OOPHPClass - a simple OO PHP Class which extends OOPHPParentClass


  include_once('OOPHPParentClass.php');


  class OOPHPChildClass extends OOPHPParentClass {      


    public function getColor() {
      return 'BLUE';
    }  
    
    public function getParentColor() {
      return parent::getColor();
    }


  }

download source, use right-click and "Save Target As..." to save with a .php extension.

testOOPHPThisParent.php

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


  include_once('OOPHPChildClass.php');


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


  echo 'TESTING OOPHPThisParent'.BR;
  echo BR;
  
  $childClass = new OOPHPChildClass();
  
  echo 'test 1 - show the child color'.BR;
  echo $childClass->getColor();
  echo BR.BR;


  echo 'test 1 - show the parent color'.BR;
  echo $childClass->getParentColor();
  echo BR.BR;


  echo 'END TESTING OOPHPThisParent'.BR;

download source, use right-click and "Save Target As..." to save with a .php extension.

output of testOOPHPThisParent.php

TESTING OOPHPThisParent


test 1 - show the child color
BLUE


test 2 - show the parent color
RED


END TESTING OOPHPThisParent

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

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