Comments on: Learn this: Strategy pattern vs Decorator pattern

By: Mohit Jethva

Mohit Jethva — Mon, 19 Dec 2011 12:02:21 +0000

Very good example keep it up……………

By: Rahul

Rahul — Thu, 15 Sep 2011 06:16:45 +0000

Strategy : Use when u have a choose from multiple standalone approaches (algorithms to address certain issue)

Decorator : Use when u have to choose from multiple approaches where each approach (may or may not) need to fabricated using certain thing in certain order.

It will help to overcome the need to specialise various combinations using inheritance methodology.

By: Blaenk

Blaenk — Sun, 29 Aug 2010 02:09:42 +0000

@Jose Noheda: awesome, that really boils it down.

Thanks Marcel. I’m new to these patterns and although they may not be too similar to the experienced, I was pretty confused at first. This cleared it up

By: Cellux

Cellux — Mon, 03 May 2010 08:01:21 +0000

I wouldn’t ask about specific patterns on an interview. Knowing a pattern in itself doesn’t give real value to a developer because it’s just a part of the story of modeling. I’ve come across a lot of developers who know most patterns of the Gang of Four if specifically asked but they simply don’t or can’t use them in practice.

I think it’s better to do a “real” OO modeling excercise where using some patterns is advantageous to address the problem. Then you test the skill that’s most relevant to your business and you still have the option to talk about relevant patterns.

What do you think?

By: John P

John P — Wed, 16 Dec 2009 22:00:35 +0000

A funny analogy in GoF is Decorator changes the skin, while Strategy changes the guts. I think this is a pretty relevant distinction.

By: Marcel

Marcel — Mon, 11 May 2009 17:19:26 +0000

@Roger 90% of the time, I will ask about the Singleton pattern (the curve ball for this is to how to "properly" do it in actionscript). Decorators and Strategy patterns will usually get mentioned. More so on strategy since they deal with interfaces and I can easily roll into questions about that. There are a few others that might get mentioned, but they definitely get mentioned more so than the others. A really good book (despite its silly cover) is Head First Design Patterns They definitely hit on most of the popular patterns and do a great job at explaining them and providing examples. Hope that helps! Marcel

By: KL

KL — Mon, 11 May 2009 16:42:33 +0000

Great article! One thing that I’d add (while subtle) is the different “type” of design patterns that Strategy and Decorator are, which may shed light on how and when to use design patterns, in general.

Stategy is a behavioral design pattern, meaning, you use it to describe or design how software components/layers interact with each other. This is usually the high level interfaces/abstract classes/object hierarchy.
Decorator, on the other hand, is more of a structural design pattern. This deals more with concrete object implementation.

In the article, it seems you are saying you have to choose to use one or the other, which I don’t think is necessarily correct. Since they happen at different levels of the architecture, they can be used together or separately.

Just my 2 cents.

By: Jose Noheda

Jose Noheda — Mon, 11 May 2009 13:46:13 +0000

Strategy allows you to replace something with an alternative implementation. Decorator transparently enhances objects. There are several patterns in GoF that look pretty similar to each other but IMO these two are not among those.

By: Roger

Roger — Mon, 11 May 2009 13:34:41 +0000

Hello,

Which design patterns would you say are common enough to be asked during an interview? everytime i hit the books i get overwhelmed with all of the GO4 design patterns, i know you should know all of them, but, it’s hard to keep track of all of them, so it should be nice to just focus on those that are “essential” or common, that is, the ones that you must know or at least be familiar with.

By: Marcel

Marcel — Mon, 11 May 2009 13:04:11 +0000

noted good point.

Thanks!