CSC/ECE 517 Summer 2008/wiki2 8 jb: Difference between revisions

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===Inheritance===
===Inheritance===
[http://en.wikipedia.org/wiki/Inheritance_(computer_science) Inheritance] is one of the fundamental tenets of [http://en.wikipedia.org/wiki/Object-oriented_programming object oriented programming]. Inheritance refers to the ability to model hierarchies classes that are related to each other through the [http://en.wikipedia.org/wiki/Is-a is-a] relationship.  
[http://en.wikipedia.org/wiki/Inheritance_(computer_science) Inheritance] is one of the fundamental tenets of [http://en.wikipedia.org/wiki/Object-oriented_programming object oriented programming]. Inheritance refers to the ability to model hierarchies classes that are related to each other through the [http://en.wikipedia.org/wiki/Is-a is-a] relationship. It is commonly agreed upon that inheritance done correctly must conform to the [http://en.wikipedia.org/wiki/Liskov_substitution_principle Liskov substitution principle].


===Delegation===
===Delegation===

Revision as of 19:25, 20 June 2008

This wiki will explore the age old debate on inheritance vs. delegation, showing the strengths and weakness of each approach, and where each approach is preferred.

Background

An in-depth description Inheritance and Delegation is out of the scope of this wiki, but a brief description of each subject will be given to get us started.

Inheritance

Inheritance is one of the fundamental tenets of object oriented programming. Inheritance refers to the ability to model hierarchies classes that are related to each other through the is-a relationship. It is commonly agreed upon that inheritance done correctly must conform to the Liskov substitution principle.

Delegation

Delegation, sometimes referred to as [1], is the concept that one class may contain an instance of, or a reference to, another class, and delegate some responsibility to that class.

Aggregation can take on another connotation, specific to data modeling, closely related to composition. Composition refers to one class owning, and therefore being responsible for the memory allocation and deallocation, another class. In this context, aggregation refers to a class simply having a reference to another class, but not taking ownership.

For the purposes of this wiki, we will use the term delegation to mean that one class delegates responsibility to another class that it contains. In this context, the issue of ownership is irrelevant.

Inheritance

What is inheritance good for?

What is inheritance not good for?

Delegation

What is delegation good for?

What is delegation not good for?

Links

Wikipedia: Inheritance
Wikipedia: Delegation
Wikipedia: Composition
Replace Inheritance With Delegation design pattern