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copied!<p>As others have already said Decorators are good for adding "options" to things... The benefits come in the way you can chain methods etc. through the decorators.</p> <p>Imagine I buy a car with options for leather interior, metallic paint and awesome spoiler... </p> <p>There are 8 different combinations of the three options but with decorators you only need three extra classes.</p> <p>The interesting thing though is the way the decorator pattern works. As a brief example:</p> <pre><code>public class MetallicPaint : Car { private Car car; public MetallicPaint(Car wrappedCar) { car = wrappedCar; } public decimal Cost() { return car.Cost() + 500; } public string Description() { return car.Description() + ", Metallic Paint"; } public string Speed() { return car.Speed(); } [... {pass through other methods and properties to the car object}] } </code></pre> <p>This isn't a complete example but highlights how the decorator can interact with the object it is decorating. And of course because it implements car it can be used just like a car in every other way (and passes through anything the decorator doesn't effect to the inner car object).</p> <p>Of course if you had multiple of these decorators with a car nested inside each would in turn add their cost, their part of the description and maybe the spoiler would alter the speed whereas the others didn't...</p> <p>In essence it allows you to modify an object in a much more modular and less fundamental way than inheritance would. Decorators should always be used as if they were the base object (in this case <code>Car</code>) so they should never expose any new methods or properties, just slightly change the effect of existing ones.</p>

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