What is StrategyA plan of action or policy designed to achieve a major or overall aim.
Why Need Pattern for Strategy• The Strategy pattern is known as a behavioural pattern - its 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
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
Why, When and How?1. Allow a class to maintain a single purpose.2. Switch statement3. Adding a new implementation will cause a class file to be modified4. Create a class for each strategy5. Use a common interface for each strategy
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.