The document discusses several object-oriented (OO) design principles including the single responsibility principle (SRP), open-closed principle (OCP), Liskov substitution principle (LSP), interface segregation principle (ISP), and dependency inversion principle (DIP). It also discusses design patterns, refactoring, and design by contract (DBC) as ways to prevent software decay over time and improve design quality. The key OO principles guide developers to create flexible, maintainable and reusable software designs.

1. The OO Design Principles Steve Zhang

3. The presentation comes from two books Author: Robert C. Martin Nick Name: Uncle Bob Agile Software Development, principles, patterns and practices

4. The pragmatic Programmer – from journeyman to master Andy Hunt Dave Thomas

7. The cost of change curve

8. Developers productivity vs. time Question: does our project manager consider this curve when doing estimations?

25. OCP – Abstraction is the key Example: Strategy pattern Client is both open and closed

33. A DIP example DIP violation DIP

39. An violation of ISP example ISP violation

40. An ISP Violation example: solution Segregated interface

43. LoD

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