One hour tour
Welcome to Object Orientated Design and the COSC427 wiki. This page will assume a basic knowledge of programming and computer science. On this page, we will not discuss the price of cheese, but hopefully you should gain a stronger understanding of object orientated design - have a read of each of the links presented.
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What is OO Programming & OO Design?
Object Orientated Programming is presently the most widely used software development paradigm in the world. In this methodology, sections of code are comprised into separate sections known as classes. At runtime, objects are created as instances of that class. The prevalent school of thought suggests that, as OO designers, our job is to model the real world. This means that the objects that are creating have boundaries that reflect what we would expect of similar objects in the real world. The term "Separation of concerns" is used to describe this idea.
What are the underlying concepts in OO programming?
OO programming is a generic term for programming in an OO fashion. In order to achieve this, certain programming languages are designed to fulfil this paradigm. Java, C++ and C# are currently the most popular OO languages; however a vast range of others exist. These include, to name a few, Smalltalk, Eiffel, JavaScript, Action Script 3, and Visual Basic. It is important to note that the classification of languages into the OO paradigm is not clear cut and may be strongly debated among practitioners.
These languages tend to contain the same types of features (as well as the unique features that define them). As mentioned above, this centres around the concepts of classes and objects. Classes, as blueprints for objects, consist of fields to define data within the class, constructors to provide the initial behaviour of objects and methods to provide the behaviour of the class. On a higher level of abstraction, classes are grouped into some kind of namespace (in Java, this is called a package). A key concept these languages address is that of encapsulation, that is where information is visible. It may be visible within globally, within a namespace, class, object, method or even smaller code block.
In addition, an important concept is inheritance. This allows classes/objects to be specialisations of a more general type. Some languages allow for the related concepts of multiple inheritance and interfaces.
What are the most important ideas in OO design?
What ideas/maxims are good to follow?
Design maxims, Riel's heuristics
How do we follow these ideas?
Extra for Experts!
If you want further information, there are whole range of further material available. The best place to start looking is the Resources page which provides information about known texts on the subject area and important papers and websites on the field. For full sets of the ideas provided above and much more information, check out the OO wisdom page. If you are interested in the story behind this material, OO culture can provide further details.
