Object (computer science)

In software development, an object is an entity semantic that has state, behavior, and identity. ^[1] ^[2] ^: 78 An object can model some part of reality or can be an invention of the design process whose collaborations with other such objects serve as the mechanisms that provide some higher-level behavior. Put another way, an object represents an individual, identifiable item, unit, or entity, either real or abstract, with a well-defined role in the problem domain.^[1]^: 76

A programming language can be classified based on its support for objects. A language that provides an encapsulation construct for state, behavior, and identity is classified as object-based. If the language also provides polymorphism and inheritance it is classified as object-oriented. A language that supports creating an object from a class is classified as class-based. A language that supports object creation via a template object is classified as prototype-based.

The concept of object is used in many different software contexts, including:

Possibly the most common use is in-memory objects in a computer program written in an object-based language.

Information systems can be modeled with objects representing their components and interfaces.^[1]^: 39

In the relational model of database management, aspects such as table and column may act as objects.^[3]

Objects of a distributed computing system tend to be larger grained, longer lasting, and more service-oriented than programming objects.

In purely object-oriented programming languages, such as Java and C#, all classes might be part of an inheritance tree such that the root class is Object, meaning all objects instances of Object or implicitly extend Object.

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Object (computer science)

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