Multiple Inheritance
Stc
Date: 2008-05-22
Time: 12:00
Room: BBL room 471
Speaker: Xiaoyu Cui
Title: Multiple inheritance
Abstract
Inheritance is a key issue in object-oriented programming since it provides a way to refine common attributes out, enabling inheriting data or operations defined in one or more classes. For those characteristics of inheritance, module re-usage in software engineering can be processed easily. Inheritance can be seen as a relationship between classes where one class would share data or operations from one or more other classes. “Without inheritance every class would be a free-standing unit, each developed from the ground-up. Different classes would bear no relationship with one another, since the developer of each provides methods in whatever manner he/she chooses. Any consistency across classes is the result of discipline on the part of the programmers [1]”. Inheritance makes it possible to specialize new classes upon pre-defined classes via adding new features, etc, rather than designing a class from scratch. With inheritance, it provides a possibility for incremental class building. Inheritance glues the concepts of classes together, so the changes on super class will be propagated to all its subclasses. Classes in inheritance is defined as: the class that inherits features from others which is called subclass, and the inherited class which is called super-class. Inheritance is classified into single or multiple inheritance. Single inheritance restricts that a subclass only can inherit from one super-class, which forms a tree hierarchy. On the other hand, multiple inheritance allows that a subclass inherits from more than one super-class which results in an inheritance graph. Comparing with single inheritance, multiple inheritance provides better feature sharing which effectively improves modularity, reusability, and incremental design, etc. As summarized in [2], four important uses of multiple inheritance are known: Multiple independent protocols, Mix and match, Sub-modularity and Separation of Interface and Implementation. Multiple inheritance brings a powerful and convenient way for software development. However, it leads to some complexity and ambiguity, therefore the programming language has to provide mechanisms to solve those problems, such that conflicts can be resolved. As mentioned in [2], those problems could be: Name Collision, Repeated Inheritance, Method combination, Difficult to implement and misuse. This paper give an overview of strategies that implement multiple inheritance, and compares differences among them. [1] B. Cox, Object Oriented Programming, an Evolutionary Approach, 1986[2] G.B.Singh, Single Versus Multiple Inheritance in Object Oriented Programming, 1995