object-oriented programming

A programming language structure wherein the data and their associated processing ("methods") are defined as self-contained entities called "objects." The norm today, object-oriented programming (OOP) languages, such as C++ and Java, provide a formal set of rules for creating and managing objects. The data are stored in a traditional relational database or in an object database if the data have a complex structure. See O-R mapping and object database.

There are three major features in object-oriented programming that makes them different than non-OOP languages: encapsulation, inheritance and polymorphism.

Encapsulation Enforces Modularity
Encapsulation refers to the creation of self-contained modules that bind processing functions to the data. These user-defined data types are called "classes," and one instance of a class is an "object." For example, in a payroll system, a class could be Manager, and Pat and Jan could be two instances (two objects) of the Manager class. Encapsulation ensures good code modularity, which keeps routines separate and less prone to conflict with each other.

Inheritance Passes "Knowledge" Down
Classes are created in hierarchies, and inheritance allows the structure and methods in one class to be passed down the hierarchy. That means less programming is required when adding functions to complex systems. If a step is added at the bottom of a hierarchy, only the processing and data associated with that unique step needs to be added. Everything else is inherited. The ability to reuse existing objects is considered a major advantage of object technology.

Polymorphism Takes any Shape
Object-oriented programming allows procedures about objects to be created whose exact type is not known until runtime. For example, a screen cursor may change its shape from an arrow to a line depending on the program mode. The routine to move the cursor on screen in response to mouse movement would be written for "cursor," and polymorphism allows that cursor to take on whatever shape is required at runtime. It also allows new shapes to be easily integrated.

OOP Languages
Used for simulating system behavior in the late 1960s, SIMULA was the first object-oriented language. In the 1970s, Xerox's Smalltalk was the first object-oriented programming language, which was used to create the graphical user interface (see Xerox Star). ACTOR and Eiffel were also earlier OOP languages.

Today, C++, C#, Java, JavaScript, Visual Basic.NET and Python are popular object-oriented languages. The following compares basic OOP terms with traditional programming. See object-oriented DBMS.

OOP           Traditional Programming

 class         define data + processing

 object        data + processing

 attribute     data (a field)

 method        function

 message       function call

 instantiate   allocate a structure

Relational vs. Object Modeling

Instead of separate employee, department and job tables, an employee class contains the data and processing for all employees. Each subclass (manager, secretary, etc.) has its own data and processing but also inherits everything from the employee class. Changes made to the employee class affect every subclass.

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objects

Contain different types of BIM content, related to the characteristics and installed use of the products and materials they represent. See also: Building information modeling

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References in classic literature

There is one element which SEEMS obviously in common among the different ways of being conscious, and that is, that they are all directed to OBJECTS. We are conscious "of" something.

The next point of criticism concerns the relation of content and object. The reference of thoughts to objects is not, I believe, the simple direct essential thing that Brentano and Meinong represent it as being.

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This instrument was designed for the purpose of rendering visible on the surface of the moon any object exceeding nine feet in diameter.

The object was to select some lofty mountain, and there are not many of these in the United States.

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This is likewise the case with regard to perception: for the object of perception is, it appears, prior to the act of perception.

If, however, our definition was not complete, if those things only are properly called relative in the case of which relation to an external object is a necessary condition of existence, perhaps some explanation of the dilemma may be found.

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But the chief ground of my satisfaction with thus method, was the assurance I had of thereby exercising my reason in all matters, if not with absolute perfection, at least with the greatest attainable by me: besides, I was conscious that by its use my mind was becoming gradually habituated to clearer and more distinct conceptions of its objects; and I hoped also, from not having restricted this method to any particular matter, to apply it to the difficulties of the other sciences, with not less success than to those of algebra.

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But as the ultimate object of these papers is to determine clearly and fully the merits of this Constitution, and the expediency of adopting it, our plan cannot be complete without taking a more critical and thorough survey of the work of the convention, without examining it on all its sides, comparing it in all its parts, and calculating its probable effects.

Without substantially accomplishing this part of their undertaking, they would have very imperfectly fulfilled the object of their appointment, or the expectation of the public; yet that it could not be easily accomplished, will be denied by no one who is unwilling to betray his ignorance of the subject.

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It was the same with other known objects. Up to five, whether shoes or shirts or pillow-slips, Michael would fetch the number requested.

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This strong propensity of the human heart would find powerful auxiliaries in the objects of State regulation.

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"I am known," said the Object, dashing itself again at the wall, "as the Consciousness of Duty Well Performed."

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