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Design patterns 101

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This presentation provide introduction to design pattern in software development and design principles behind it.

Example source code is available at
https://github.com/RiteshAgrawal/design-pattern-101

Published in: Software
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Design patterns 101

  1. 1. Design Patterns 101
  2. 2. $ whoami Ritesh Agrawal udr.ritesh@gmail.com Software Engineer at Cyware Labs https://www.linkedin.com/in/riteshagrawal18/
  3. 3. Considerations during Software Design ● Changing requirement/Feature Extension ● Technology changes ● Reusability ● Reduce Impact of code change
  4. 4. What is Design Pattern? ● Solution for the common software design problem ● It is a concept not implementation ● Technology independent
  5. 5. How?
  6. 6. Basics of OOP ● Abstraction ● Encapsulation ● Inheritance ● Polymorphism
  7. 7. Design Principles
  8. 8. Do Not Repeat Yourself (DRY) ● Aimed at reducing repetition of code ● Use of helper classes and utilities
  9. 9. Single Responsibility Principle ● Class, module or function should have single responsibility ● High Cohesiveness ● Single Reason of change
  10. 10. Open-Close Principle ● Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification. ● Classes allow to subclass and alter the behaviour but not allowed to change the existing code
  11. 11. Program to Interfaces, not Implementations ● Focus on what to be done rather than how ● Interact at more abstract level ● Helps in changing the details without affecting the client or caller
  12. 12. Encapsulate What Varies ● Change is the only constant ● Isolate the implementation details which changes frequently ● Can be business logic, library, interface, etc. ● Legacy code handling
  13. 13. Design Patterns
  14. 14. Strategic Pattern ● This pattern allows usage of different strategies by encapsulating the algorithm ● Algorithm can vary independent of the client ● Client knows about the interface but not implementation
  15. 15. Adapter ● Joins functionality of incompatible interface ● Generalize interface of other functionality which can be helpful to change it in future ● Using different product, libraries
  16. 16. Factory ● Abstracts process of creational of new objects ● Reduces code coupling by abstracting details of concrete classes
  17. 17. Singleton ● Restricts creation of one object per class ● Helpful in creating db connection objects
  18. 18. Question/Feedback ?
  19. 19. Thanks

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