Object-oriented Programming - Fundamental Features and Concepts

Fundamental Features and Concepts

See also: List of object-oriented programming terms

A survey by Deborah J. Armstrong of nearly 40 years of computing literature identified a number of fundamental concepts, found in the strong majority of definitions of OOP.

Not all of these concepts are to be found in all object-oriented programming languages. For example, object-oriented programming that uses classes is sometimes called class-based programming, while prototype-based programming does not typically use classes. As a result, a significantly different yet analogous terminology is used to define the concepts of object and instance.

Benjamin C. Pierce and some other researchers view as futile any attempt to distill OOP to a minimal set of features. He nonetheless identifies fundamental features that support the OOP programming style in most object-oriented languages:

  • Dynamic dispatch – when a method is invoked on an object, the object itself determines what code gets executed by looking up the method at run time in a table associated with the object. This feature distinguishes an object from an abstract data type (or module), which has a fixed (static) implementation of the operations for all instances. It is a programming methodology that gives modular component development while at the same time being very efficient.
  • Encapsulation (or multi-methods, in which case the state is kept separate)
  • Subtype polymorphism
  • Object inheritance (or delegation)
  • Open recursion – a special variable (syntactically it may be a keyword), usually called this or self, that allows a method body to invoke another method body of the same object. This variable is late-bound; it allows a method defined in one class to invoke another method that is defined later, in some subclass thereof.

Similarly, in his 2003 book, Concepts in programming languages, John C. Mitchell identifies four main features: dynamic dispatch, abstraction, subtype polymorphism, and inheritance. Michael Lee Scott in Programming Language Pragmatics considers only encapsulation, inheritance and dynamic dispatch.

Additional concepts used in object-oriented programming include:

  • Classes of objects
  • Instances of classes
  • Methods which act on the attached objects.
  • Message passing
  • Abstraction

Read more about this topic:  Object-oriented Programming

Famous quotes containing the words fundamental, features and/or concepts:

    “One of the fundamental reasons why so many doctors become cynical and disillusioned is precisely because, when the abstract idealism has worn thin, they are uncertain about the value of the actual lives of the patients they are treating. This is not because they are callous or personally inhuman: it is because they live in and accept a society which is incapable of knowing what a human life is worth.”
    —John Berger (b. 1926)

    “These, then, will be some of the features of democracy ... it will be, in all likelihood, an agreeable, lawless, particolored commonwealth, dealing with all alike on a footing of equality, whether they be really equal or not.”
    —Plato (c. 427–347 B.C.)

    “Once one is caught up into the material world not one person in ten thousand finds the time to form literary taste, to examine the validity of philosophic concepts for himself, or to form what, for lack of a better phrase, I might call the wise and tragic sense of life.”
    —F. Scott Fitzgerald (1896–1940)