The document discusses the strategy pattern, which allows selecting algorithms or behaviors at runtime. It defines a family of algorithms, encapsulates each one, and makes them interchangeable. The strategy pattern is useful when wanting to choose algorithms dynamically, like for sorting or file compression. It keeps classes focused on a single purpose by extracting conditional logic into strategy objects. The document provides examples of how the strategy pattern can be implemented and used, such as for a robot identifying different objects or relationships.

1. Strategy Pattern
Shahriar Iqbal Chowdhury
Monjurul Habib
Code Name: Remington
http://www.facebook.com/groups/netter/

2. What is Strategy
A plan of action or policy designed to achieve a major or overall aim.

3. Why Need Pattern for Strategy
• The Strategy pattern is known as a behavioural pattern - it's used to
manage algorithms, relationships and responsibilities between
objects.
• The Strategy pattern is to be used where you want to choose the
algorithm to use at runtime. A good use of the Strategy pattern would
be saving files in different formats, running various sorting
algorithms, or file compression

4. Strategy Pattern Says
• Define a family of algorithms, encapsulate each one, and make them
interchangeable. Strategy lets the algorithm vary independently from
clients that use it
OR

5. Why, When and How?
1. Allow a class to maintain a single purpose.
2. Switch statement
3. Adding a new implementation will cause a class file to be modified
4. Create a class for each strategy
5. Use a common interface for each strategy

6. Class Diagram

7. Pattern less Implementation

8. Context IStrategy

9. Concrete Strategy UPS Concrete Strategy USPS

10. WALL-E & Strategy
Strategy : Capable to Identify Object Strategy : Identify and Recycle
Garbage

11. Strategy : Identify Friend Strategy : Identify Girl Friend 

12. Strategy : Identify New Hope For
Mankind

13. Strategy @.Net Framework
• Array and ArrayList provide the capability to sort. Sort method will
use the IComparable implementation for each element to handle the
comparisons. Leaving the choice of comparison algorithm up to the
user of the class like this is an example of the Strategy pattern.
• The use of a Predicate<T> delegate in the FindAll<T> method lets the
caller use any method as a filter for the List<T> so long as it takes the
appropriate object type and returns a Boolean.

14. That’s It!!