1. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Basic OO Technology Technology determines the effectiveness of the approach

2. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Concepts Encapsulation Data hiding Inheritance Polymorphism

3. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Encapsulation An object contains data and methods It provides a boundary: to the world outside to its ‘children’

4. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Information hiding Reduces complexity Allows you to defer implementations Remember: Ignorance is bliss Helps in decoupling components

5. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Inheritance A mechanism for code-sharing Supports incremental development Organize by classification Allows for abstract interfaces

6. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Polymorphism An object may have multiple types An abstract type: when it is used A concrete type: when it is created An object’s type is determined by its behavior An object’s type is determined by the messages it allows

7. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie

8. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Design by Contract formal basis -- pre and post conditions refinement -- by inheritance or polymorphism runtime checks -- division of responsibility see Ch. 3, Contracts

9. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Design by Contract Abstract Data Types ADT = state + behavior Object-Oriented Modeling data oriented

10. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Responsibilities what rather than how to specify behavior Client client/server model makes request to perform a service Server provides service upon request

11. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie object = information + responsibilities Contracts a set of services Behavioral refinement improving contracts

12. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Conformance -- behavioral refinement if B refines A then B may be used wherever A is allowed

13. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Attributes refine more information Services better services Contracts more and better services A better service fewer restrictions for the client more obligations for the server

14. vrije Universiteit amsterdamPostacademische Cursus Informatie Technologie Object-Oriented Modeling prototyping, specification, refinement, interactions OOP = Contracts + Refinements