CODEWITHSUNDEEP
phpdesign-patterns
user838531
user838531

Reputation: 488

is this a decorator pattern (PHP)?

I was watching a Lynda.com PHP Design Patterns tutorial when the tutor presented this solution to a challenge:

index.php:

include_once 'decorator.php';

$object = new Decorator();
$object->sentence = "This is a sample sentence that we're going to manipulate in the Decorator.";

// This should output: this is a sample sentence that we're going to manipulate in the decorator.
echo $object->lower();

// This should output: THIS IS A SAMPLE SENTENCE THAT WE'RE GOING TO MANIPULATE IN THE DECORATOR.
echo $object->uppercase();

decorator.php:

class Decorator
{
    public $sentence = '';

    public function lower()
    {
        return strtolower($this->sentence);
    }

    public function uppercase()
    {
        return strtoupper($this->sentence);
    }
}

Why is this a decorator pattern? All I see is the instantiation of an object and accessing two of the objects methods.

Upvotes: 2

Views: 540

Answers (2)

Ziya Vakhobov
Ziya Vakhobov

Reputation: 465

What you did is not a decorator pattern. You just created Utility class for string if you really want to convert your utility class into decorator then just see below:

<?php

interface StringInterface
{
    public function string();
}

class StringDecorator implements StringInterface
{
    private $text;

    public function __construct($text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return  $this->text ;
    }
}


class StringLower implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return strtolower( $this->text );
    }
}
class StringUpper implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return strtoupper( $this->text );
    }
}
class StringTrim implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return trim( $this->text );
    }
}

// For Lowercase
$decorator=new StringLower( new StringDecorator("Text") );
// Output: Lowercase Text to text
$text=$decorator->string();

// For Uppercase
$decorator= new StringUpper( new StringDecorator("text") );
// Output: Uppercase text to Text
$text=$decorator->string();

//TO normalized text from " TeXT " to text.
$decorator= new StringTrim( new StringLower( new StringDecorator(" TeXT ") ) );
// Output: normalized text from " TeXT " to text also extra space removed from left and right.
$text=$decorator->string();

This are your case examples If you need more real world example see here, I gave here good example from real world.

Upvotes: 1

casablanca
casablanca

Reputation: 70701

The example you posted is not a decorator, it simply provides a new interface (lower and uppercase) on top of a string. A decorator adds behaviour without changing the underlying interface.

A typical example of decorators is literally decorating graphical elements. For example:

interface Shape {
  draw();
}

class Rectangle implements Shape { ... }
class Circle implements Shape { ... }

class BorderDecorator implements Shape {
  Shape shape;

  draw() {
    shape.draw();
    drawBorder();
  }
}

All of the classes above have the same interface, so if a function needs a Shape, you can pass in a plain old Rectangle or you can wrap it in a BorderDecorator to get a rectangle with a border.

Upvotes: 2

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