Better Understand the 'Strategy' Design Pattern

Posted by Imran Omar Bukhsh on Programmers See other posts from Programmers or by Imran Omar Bukhsh
Published on 2011-01-30T08:11:55Z Indexed on 2011/01/30 15:32 UTC
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Greetings

Hope you all are doing great. I have been interested in design patterns for a while and started reading 'Head First Design Patterns'. I started with the first pattern called the 'Strategy' pattern. I went through the problem outlined in the images below and first tried to propose a solution myself so I could really grasp the importance of the pattern. So my question is that why is my solution ( below ) to the problem outlined in the images below not good enough. What are the good / bad points of my solution vs the pattern? What makes the pattern clearly the only viable solution ? Thanks for you input, hope it will help me better understand the pattern.

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MY SOLUTION

Parent Class: DUCK

<?php
class Duck
{
 public  $swimmable;
 public  $quackable;
 public  $flyable;

 function display()
 {
  echo "A Duck Looks Like This<BR/>";
 }

 function  quack()
 {
  if($this->quackable==1)
  {
   echo("Quack<BR/>");
  }
 }

 function swim()
 {
  if($this->swimmable==1)
  {
   echo("Swim<BR/>");
  }
 }

 function  fly()
 {
  if($this->flyable==1)
  {
   echo("Fly<BR/>");
  }
 }


}
?>

INHERITING CLASS: MallardDuck

<?php
class MallardDuck extends Duck
{
 function MallardDuck()
 {
  $this->quackable = 1;
  $this->swimmable = 1;
 }

 function display()
 {
  echo "A Mallard Duck Looks Like This<BR/>";
 }
}
?>

INHERITING CLASS: WoddenDecoyDuck

<?php
class WoddenDecoyDuck extends Duck
{
 function woddendecoyduck()
 {
  $this->quackable = 0;
  $this->swimmable = 0;
 }

 function display()
 {
  echo "A Wooden Decoy Duck Looks Like This<BR/>";
 }
}

Thanking you for your input.

Imran

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