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Lecture # 3Ahmed Safwat
Muhamad HeshamAbdelrahman Al-Ogail
Let’s break the ice….
Agenda
You can solve it yourself! Meet Singleton pattern. Call for a new requirement. First try for implementation. Bad smell code. Who’s our hero?
Agenda (con’t)
Meet today’s pattern.Break!! Second try for implementation. Common uses. What’s next?
What’s a design pattern?
A design pattern is: Set of class(es). Interact together. In UML (class diagram).
Informa
l
Let’s solve it ourselves
How do we ensure that
a class has only one instance and that
the instance is easily accessible?
Unique
Global
Access
Singleton
The Singleton assures that there is one and only one instance of a class, and provides a global point of access to it
Make sure that there can be one and only one instance of a class
Formal
Singleton
Our Current Status
What have we did till now?
Call for New Requirement
Each level can be in one of two styles: Pharonic Aztec
First level is Aztec. Second and third level is
Pharonic.
First Try Implementation
1. We need find where we decide which image we load.
2. Categorize images to 2 sets, Pharonic an Aztec.
Our Code Smells Bad
Each time we add a new
theme we add piles of if-else statements.
Our class do more than
its job (SCSR).
My Restaurant Drinks
My Restaurant Drinks
My Restaurant Drinks
Water Bottle
Coke softOrange
softLemon
soft
Who’s our hero?
So, what we can call it?
Let’s Google it!
Break
Meet Abstract Factory
Meet Abstract Factory
Coke soft
Lemon soft
Second Try for Implementation
Just Code It
Common Uses
What’s Next?
Consequences of Factory Pattern.
Factory Method Pattern.
Implement Factory Pattern using Prototype Pattern.
