Strategy Design Pattern

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Strategy Pattern

Copyright 2016. Jyaasa Technologies.

http://jyaasa.com

Ganesh Kunwar

Sr. Software Engineer

Jyaasa Technologies


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What is Strategy Pattern?


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Ktm ButwalTaxi Plan Taxi

Ktm. Airport

Bhairahawa Airport

Ktm ButwalTaxi Bus

Kalanki

Ktm ButwalTaxi Bus BusKalanki

Chitwan

Strategy 1

Strategy 2

Strategy 3


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Wikipedia Definition

the strategy pattern (also known as the policy pattern) is a software design pattern that enables an algorithm's behavior to be selected at runtime. The strategy pattern

● defines a family of algorithms,● encapsulates each algorithm, and● makes the algorithms interchangeable within that

family.

https://en.wikipedia.org/wiki/Design_pattern_(computer_science)

https://en.wikipedia.org/wiki/Algorithm


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When to Use?

Shopping Mall Example- Accept customer detail- Calculate bill amount- Apply discount based on the day of week

- Monday - High discount (10%)- Friday - Low discount (5%)


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Where does the discount logic reside?

Inside ShoppingMall class

Or

Outside ShoppingMall class


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Open closed principle

- software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification

- New discount logic may be applied in future

- Not reusable - Same discount strategy can be use in other shopping mall


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Separate discount logic from ShoppingMall class


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Context Strategy


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=> grill = Grill.new(HotDog.new)=> grill.grilling # => "Grilling the hot dogs!"

=> grill.food = Hamburger.new

=> grill.grilling # => "Grilling the hamburgers!"

=> grill.food = VeggiePatty.new

=> grill.grilling # => "Grilling the veggie patties!"


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References

- https://dockyard.com/blog/2013/07/25/design-patterns-strategy-pattern - https://en.wikipedia.org/wiki/Strategy_pattern - https://sourcemaking.com/design_patterns/strategy

https://dockyard.com/blog/2013/07/25/design-patterns-strategy-pattern

https://dockyard.com/blog/2013/07/25/design-patterns-strategy-pattern

https://en.wikipedia.org/wiki/Strategy_pattern

https://en.wikipedia.org/wiki/Strategy_pattern

https://sourcemaking.com/design_patterns/strategy

https://sourcemaking.com/design_patterns/strategy

Thank you!

Lets Discuss

github.com/glunwar@gkunwar1

Copyright 2015. Jyaasa Technologies. Copyright 2016. Jyaasa Technologies.

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Strategy Design Pattern

Software

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