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Extending Object Oriented Programming concepts further with abstraction and interfaces


Few days back I wrote for Solid and Grasp principles for oops

http://www.developerscloud.org/2014/08/oops-beyond-four-pillars-solid-and-grasp.html.

Now I am again extending it to make it more matured way to write code.

Let start with coupling and cohesion.

Loose/Low Coupling
  • low dependency between classes;
  • low impact in a class of changes in other classes
  • high reuse potential


High Cohesion
  • measure of how strongly-related or focused the responsibilities of a single module are
  • If methods of a class tend to be similar in many aspects, then the class have high cohesion
  • In highly-cohesive system, code readability and the likelihood of reuse is increased, while complexity is kept manageable.


Also check
  • Encapsulate what varies
  • Favor Composition over Inheritance
  • Program to interface not implementation
  • Strive for loosely coupled design between objects that interact


For Interfaces
  • Like an abstract base class: any non-abstract type inheriting the interface must implement all its members.
  • Cannot be instantiated directly.
  • Can contain events, indexers, methods and properties.
  • Contain no implementation of methods.
  • Classes and structs can inherit from more than one interface.
  • An interface can itself inherit from multiple interfaces.

·          
Difference between Interface and abstract base class

  • Abstract class can have non abstract methods, methods of an interface are effectively abstract since they contain only the signature
  • A class can implement any no of interfaces, but can subclass at most one abstract class.
  • An abstract class can declare and use variables, an interface cannot.
  • An abstract class can have methods whose access is public, internal, protected, protected internal and private. Interface members implicitly have public access.
  • An abstract class can declare constructor, an interface cannot.
  • An abstract class can have delegate, an interface cannot
In my next post i'll give you an example on how to implement implicit, explicit and generic interface in and enterprise level application.



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