In software development, an object is an entity that has state, behavior, and identity.[1]: 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.[2]
- 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.
See also
- Actor model – Model of concurrent computation
- Business object – Entity within a multi-tiered software application
- Instance (computer science) – Concrete manifestation of an object (class) in software development
- Object lifetime – Time period between the creation and destruction of an object-oriented programming instance
- Object copying – Technique in object-oriented programming
- Semantic Web – Extension of the Web to facilitate data exchange
References
- ^ 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.
- ^ Oppel, Andy (2005). SQL Demystified. McGraw Hill. p. 7. ISBN 0-07-226224-9.
External links
- What Is an Object? from The Java Tutorials