Wednesday, August 25, 2010

Design Patterns by Metaphors - Part I (Creational Patterns)

From today, I am starting blog series on Design Patterns. There are numerous technical posts, material on this subject out there awaiting just googling to get discovered. So I don't want to repeat same here. What I will be trying to do is explain them using metaphors, in layman terms, so that newbies can understand easily and can adapt them with ease.

I will start with Creational Patterns.

Creational Patters:

Are patterns which guides you in tackling object creation challenges in certain scenarios.

Abstract Factory:




Simpson lives in world of SONY. Every electronic appliance in his world is of SONY. But he wants agility to move to other electronic worlds as well, may be Samsung in future. In order for him to able to move to different worlds without much effort, he uses remote covers over top of particular remote to access functionality. All remotes in electronics will support that cover. Tomorrow even if he changes to Samsung, he will still be able to use them with his cover.
Due to this common cover fitting all remotes to access only common minimum features, he will not be able to access any special button which might be specific to a particular remote. He trades this for flexibility to be able to move to different worlds.

Builder Pattern




Result is so varied that we do not have common interface for end result. In case of Abstract Factory we had common interface for end result.
User Will provide which builder to use to Director.

Factory Method




Whenever Simpson requests for car to Car Factory, he will always get latest car available at that time, wrapped under Car prototype cover. As time evolves, as new models gets added, he still gets latest models but wrapped in car prototype. He will get latest engine performance, latest ABS, latest electronics working under hood.
But all cars are wrapped under car prototype, which has only minimum control points. Though he can experience latest engine performance with car prototypes accelerator, he cannot access to car GenX’s latest Blue Me feature as that is wrapped under car prototype.

Abstract vs Factory


Thanks to David Hayden for making it so clear in his post at here.

Singleton

4 comments:

vijay said...

hey excellent.thanku.but i would like to get other patterns also please help me.

vijay said...

please ..........

Kiran Kumar G said...

Appreciate your feedback.
Due to my recent move to Microsoft in my day job, I am not able to manage time to write blogs. But I promise you I will come with rest of patterns soon. Sorry for delay!!

Luiz Gustavo S. de Souza said...

Excelent!