Object oriented class based programming Languages

Class-based Object-oriented programming languages support objects defined by their class. Class definitions include member data. Polymorphic functions parameterized by the class of some of their arguments are typically called methods.

In languages with single dispatch, classes typically also include method definitions. In languages with multiple dispatch, methods are defined by generic functions. There are exceptions where single dispatch methods are generic functions (e.g. Bigloo's object system).

• Structure
  A class contains data field descriptions (or properties, fields, data members, or attributes). These are usually field types and names that will be associated with state variables at program run time; these state variables either belong to the class or specific instances of the class.
• Behavior
  The behavior of class or its instances is defined using methods. Methods are subroutines with the ability to operate on objects or classes. These operations may alter the state of an object or simply provide ways of accessing it.[6] Many kinds of methods exist, but support for them varies across languages.
• The concept of class interface
  Every class implements (or realizes) an interface by providing structure and behavior. Structure consists of data and state, and behavior consists of code that specifies how methods are implemented.[9] There is a distinction between the definition of an interface and the implementation of that interface; however, this line is blurred in many programming languages because class declarations both define and implement an interface. Object-oriented programming methodology dictates that the operations of any interface of a class are to be independent of each other. It results in a layered design where clients of an interface use the methods declared in the interface.

Class-based Object-oriented programming languages support objects defined by their class. Class definitions include member data. Message passing is a key concept (if not the key concept) in Object-oriented languages. Polymorphic functions parameterized by the class of some of their arguments are typically called methods. In languages with single dispatch, classes typically also include method definitions. In languages with multiple dispatch, methods are defined by generic functions.