object-oriented programming

programming (OOP) The use of a class of programming

languages and techniques based on the concept of an "object"

which is a data structure (abstract data type) encapsulated

with a set of routines, called "methods", which operate on

the data. Operations on the data can _only_ be performed via

these methods, which are common to all objects that are

instances of a particular "class". Thus the interface to

objects is well defined, and allows the code implementing the

methods to be changed so long as the interface remains the

same.

Each class is a separate module and has a position in a

"class hierarchy". Methods or code in one class can be

passed down the hierarchy to a subclass or inherited from a

superclass. This is called "inheritance".

A procedure call is described as invoking a method on an

object (which effectively becomes the procedure's first

argument), and may optionally include other arguments. The

method name is looked up in the object's class to find out how

to perform that operation on the given object. If the method

is not defined for the object's class, it is looked for in its

superclass and so on up the class hierarchy until it is found

or there is no higher superclass.

OOP started with SIMULA-67 around 1970 and became

all-pervasive with the advent of C++, and later Java.

Another popular object-oriented programming language (OOPL) is

Smalltalk, a seminal example from Xerox's Palo AltoResearch Center (PARC). Others include Ada, ObjectPascal, Objective C, DRAGOON, BETA, Emerald, POOL,

Eiffel, Self, Oblog, ESP, Loops, POLKA, and

Python. Other languages, such as Perl and VB, permit,

but do not enforce OOP.

FAQ .

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Usenet newsgroup: news:comp.object.

(2001-10-11)