PHP/Class/Inheritance

Basic Inheritance

 
<?
    class Dog {
            public function bark( ) {
                    print "Woof!\n";
            }
    }
    class Poodle extends Dog {
    }
?>

Class Inheritance

 
<?php
     class ParentClass {
          public $parentvar;
          public function parentOne() {
               echo "Called parentOne()\n";
          }
          private function parentTwo() {
               echo "Called parentTwo()!\n";
          }
     }
     class ChildClass extends ParentClass {
          public function childOne() {
               echo "Called childOne()!\n";
          }
     }
     $v = new ChildClass();
     $v->parentOne();
?>

Class Member Binding in PHP

 
<?php
     class ParentClass {
          public function callMe() {
               $this->anotherCall();
          }
          public function anotherCall() {
               echo "Parent called!\n";
          }
     }
     class ChildClass extends ParentClass {
          public function anotherCall() {
               echo "Child called!\n";
          }
     }
     $child = new ChildClass;
     $child->callMe();
?>

Creating a Class That Inherits from Another

 
<?php
class Item {
  var $name;
  function Item( $name="item", $code=0) {
    $this->name = $name;
    $this->code = $code;
  }
  function getName() {
   return $this->name;
  }
 }
 class PriceItem extends Item {
 }
 $item = new PriceItem( "widget", 5442 );
 print $item->getName ();
 ?>

Define an Executive class that inherits Employee

 
<?php
   class Employee {
      private $name;
      function setName($name) {
         if ($name == "") echo "Name cannot be blank!";
         else $this->name = $name;
      }
      function getName() {
         return "My name is ".$this->name."<br />";
      }
   }
   class Executive extends Employee {
      function pillageCompany() {
         echo "I"m selling company assets to finance my yacht!";
      }
   }
   $exec = new Executive();
   $exec->setName("R");
   echo $exec->getName();
   $exec->pillageCompany();
?>

Example of Inheritance

 
<?php
class cd {
    public $artist;
    public $title;
    protected $tracks;
    private $disk_id;
    public function __construct() {
        $this->disk_id = sha1("cd" . time() . rand());
    }
    public function get_disk_id() {
        return $this->disk_id;
    }
}
class cd_album extends cd {
    protected $num_disks;
    public function __construct($disks = 1) {
        $this->num_disks = $disks;
        parent::__construct();
    }
    public function is_multi_cd() {
        return ($this->num_disks > 1) ? true : false;
    }
}
$mydisk = new cd_album(3);
echo "<p>The compact disk ID is: ", $mydisk->get_disk_id(), "</p>";
echo "<p>Is this a multi cd? ",
    ($mydisk->is_multi_cd()) ? "Yes" : "No",
    "</p>";
?>

extends and implement

<?php
   class Employee {
      private $name;
      function setName($name) {
         if ($name == "") 
           echo "Name cannot be blank!";
         else 
           $this->name = $name;
      }
      function getName() {
         return "My name is ".$this->name."<br />";
      }
   }
   interface MyInterface
   {
      function account();
      function doc();
   }
   class Executive extends Employee implements MyInterface
   {
      private $totalStockOptions;
      function account()
      {
         echo "account";
      }
      function doc()
      {
         echo "doc";
      }
   }
   class Assistant extends Employee implements MyInterface
   {
      function takeMemo() {
         echo "memo";
      }
      function account(){
         echo "memo";
      }
      function doc(){
         echo "Start small fire in the trash can.";
      }
   }

?>

inheritance example

 
<?php
class Bird {
  private $name;
  private $breed;
  private $price;
  
  public function __construct($name, $breed, $price = 15) {
    $this->setName ( $name );
    $this->setBreed ( $breed );
    $this->setPrice ( $price );
  }
  public function birdCall() {
    printf ( "<p>%s says: *chirp*</p>\n", $this->getName () );
  }
  public function display() {
    printf ( "<p>%s is a %s and costs \$%.2f.</p>", $this->getName (), $this->getBreed (), $this->getPrice () );
  
  }
}
class Parrot extends Bird {
  public function birdCall() {
    printf ( "<p>%s says: *squawk*</p>\n", $this->getName () );
  }
  public function __construct($name) {
    parent::__construct ( $name, "parrot", 25 );
  }
  public function curse() {
    printf ( "<p>%s</p>\n", $this->getName () );
  }
}
?>

Overriding parent methods

 
class DB {
 public $result;
 function getResult() {
  return $this->result;
 }
 function query($sql) {
  error_log("query() must be overridden by a database-specific child");
  return false;
 }
}
class MySQL extends DB {
 function query($sql) {
  $this->result = mysql_query($sql);
 }
}

subclass and parent class

<?php
   class Employee {
      private $name;
      function setName($name) {
         if ($name == "") 
           echo "Name cannot be blank!";
         else 
           $this->name = $name;
      }
      function getName() {
         return "My name is ".$this->name."<br />";
      }
   }
   class Executive extends Employee {
      function pillageCompany() {
         echo "hi!";
      }
   }
   $exec = new Executive();
   $exec->setName("Joe");
   echo $exec->getName();
   $exec->pillageCompany();
?>

Three levels of inheritance

<?php
   class Employee {
      private $name;
      function setName($name) {
         if ($name == "") echo "Name cannot be blank!";
            else $this->name = $name;
      }
      function getName() {
         return "My name is ".$this->name."<br />";
      }
   }
   
   class Executive extends Employee {
      function methodB() {
         echo " my yacht!";
      }
   }
   
   class CEO extends Executive {
      function methodC() {
            echo "tuck";
      }
   }
   $ceo = new CEO();
   $ceo->setName("Joe");
   $ceo->methodB();
   $ceo->methodC();
?>

Using inheritance to efficiently represent various vehicle types

 
<?
class Vehicle {
     var $model;
     var $current_speed;
     function setSpeed($mph) {
          $this->current_speed = $mph;
     }
     function getSpeed() {
          return $this->current_speed;
     }
}
class Auto extends Vehicle {
    var $fuel_type;
    function setFuelType($fuel) {
          $this->fuel_type = $fuel;
    }
     function getFuelType() {
          return $this->fuel_type;
     }
}
class Airplane extends Vehicle {
     var $wingspan;
     function setWingSpan($wingspan) {
          $this->wingspan = $wingspan;
     }
     function getWingSpan() {
          return $this->wingspan;
     }
}
?>

Using the extends keyword to define a subclass

 
<?php
class Cat {
    var $age;
    function Cat($new_age){
        $this->age = $new_age;
    }
    function Birthday(  ){
        $this->age++;
    }
}
class MyCat extends Cat {
    function MyCat(  ) {
    }
    function sleep(  ) {
        echo("Zzzzzz.<br />");
    }
}
$fluffy=new MyCat(  );
$fluffy->Birthday(  );
$fluffy->sleep(  );
echo "Age is $fluffy->age <br />";
?>

Using the parent construct

 
<?php
class Cat {
    var $age;
    function Cat($new_age){
        $this->age = $new_age;
    }
    function Birthday(  ){
        $this->age++;
    }
    function Eat(  ){
        echo "Chomp chomp.";
    }
    function Meow(  ){
        echo "Meow.";
    }
}
class MyCat extends Cat {
    function MyCat(  ) {
    }
    function eat(  ) {
        parent::eat(  );
        $this->meow(  );
    }
}
?>