In software development, an object is a semantic entity that has state, behavior, and identity.[1][2][3][4] 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.[5][dubious – discuss] 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.[6]
- 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.
See also
edit- Attribute (object-oriented programming)
- Business object
- Class (computer programming)
- Class-based programming
- Data transfer object
- Declaration (computer programming)
- Distributed object
- Instance (computer science)
- Metaobject
- Method (computer programming)
- Object-capability model
- Object composition
- Object copying
- Object graph
- Object lifetime
- Object-based language
- Object-oriented programming
- Pointer (computer programming)
- Reference (computer science)
- Semantics (logic)
- Value object
References
edit- ^ a b c Grady Booch; Robert Maksimchuk; Michael Engle; Bobbi Young; Jim Conallen; Kelli Houston (April 30, 2007). Object-Oriented Analysis and Design with Applications (3 ed.). Addison-Wesley Professional. ISBN 978-0201895513.
- ^ Adolfo M. Nemirovsky. "Is Schrödinger's Cat Object-Oriented?" (PDF). www.literateprogramming.com.
- ^ "Distributed Object-Based Programming Systems". dl.acm.org.
- ^ "Dimensions of Object-Based Language Design". dl.acm.org.
- ^ "A Brief History of the Object-Oriented Approach" (PDF). Archived from the original (PDF) on 2017-08-08.
- ^ Oppel, Andy (2005). SQL Demystified. McGraw Hill. p. 7. ISBN 0-07-226224-9.
External links
edit- What Is an Object? from The Java Tutorials
