English_topic_1_kurs / Object-Oriented Programming

Object-Oriented Programming

Object-Oriented Programming (OOP), in computer science, type of high-level computer language that uses self-contained, modular instruction sets for defining and manipulating aspects of a computer program. These discrete, predefined instruction sets are called objects and they may be used to define variables, data structures, and procedures for executing data operations. In OOP, objects have built-in rules for communicating with one another. By using objects as stable, preexisting building blocks, programmers can pursue their main objectives and specify tasks from the top down, manipulating or combining objects to modify existing programs and to create entirely new ones.

One especially powerful feature of OOP languages is a property known as inheritance. Inheritance allows an object to take on the characteristics and functions of other objects to which it is functionally connected. Programmers connect objects by grouping them together in different classes and by grouping the classes into hierarchies. These classes and hierarchies allow programmers to define the characteristics and functions of objects without needing to repeat source code, the coded instructions in a program. Thus, using OOP languages can greatly reduce the time it takes for a programmer to write an application, and also can reduce the size of the program. OOP languages are flexible and adaptable, so programs or parts of programs can be used for more than one task. Programs written with OOP languages are generally shorter in length and contain fewer bugs, or mistakes, than those written with non-OOP languages.

Object-oriented programming began with Simula, a programming language developed from 1962 to 1967 by Ole-Johan Dahl and Kristen Nygaard at the Norwegian Computing Center in Oslo, Norway. Simula introduced definitive features of OOP, including objects and inheritance. In the early 1970s Alan Kay developed Smalltalk, another early OOP language, at the Palo Alto Research Center of the Xerox Corporation. Smalltalk made revolutionary use of a graphical user interface (GUI), a feature that allows the user to select commands using a mouse. GUIs became a central feature of operating systems such as Macintosh OS and Windows.

The most popular OOP language is C++, developed by Bjarne Stroustrup at Bell Laboratories in the early 1980s. In 1995 Sun Microsystems, Inc., released Java, an OOP language that can run on most types of computers regardless of platform. In some ways Java represents a simplified version of C++ but adds other features and capabilities as well, and it is particularly well suited for writing interactive applications to be used on the World Wide Web.