Instance (computer science)
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Concrete manifestation of an object (class) in software development
For other uses, see Instance (disambiguation).
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In computer science, an instance or token (from metalogic and metamathematics) is an occurrence of a software element that is based on a type definition. [1] : 1.3.2 When created, an occurrence is said to have been instantiated, and both the creation process and the result of creation are called instantiation.
Examples
[edit ]- Class instance
- An object-oriented programming (OOP) object created from a class. Each instance of a class shares a data layout but has its own memory allocation.
- Procedural instance
- Although isn't common the use of this concept in computer science each procedure call also was considered an "instance" of the procedure in Simula. [1] : 1.3.2
- Computer instance
- An occurrence of a virtual machine which typically includes storage, a virtual CPU.
- Polygonal model
- In computer graphics, it can be instantiated in order to be drawn several times in different locations in a scene which can improve the performance of rendering since a portion of the work needed to display each instance is reused.
- Program instance
- In a POSIX-oriented operating system, it refers to an executing process. It is instantiated for a program via system calls such as fork() and exec(). Each executing process is an instance of a program which it has been instantiated from.[2]
References
[edit ]- ^ a b Dahl, Ole-Johan; Myhrhaug, Bjørn; Nygaard, Kristen (1970). Common Base Language (PDF) (Report). Norwegian Computing Center. Archived from the original on 2024年09月19日. Retrieved 20 August 2025.
- ^ Bach, Maurice J. (1986). The Design of the UNIX Operating System. Prentice Hall. pp. 10, 24. ISBN 0-13-201799-7. Archived from the original on 2010年03月15日.