Poltergeist (computer programming)

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In computer programming, a poltergeist (or gypsy wagon) is a short-lived, typically stateless object used to perform initialization or to invoke methods in another, more permanent class. It is considered an anti-pattern. The original definition is by Michael Akroyd at the 1996 Object World West Conference:[ citation needed ]

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As a gypsy wagon or a poltergeist appears and disappears mysteriously, so does this short lived object. As a consequence the code is more difficult to maintain and there is unnecessary resource waste. The typical cause for this anti-pattern is poor object design.

A poltergeist can often be identified by its name; they are often called "manager_", "controller_", "supervisor", "start_process", etc.

Sometimes, poltergeist classes are created because the programmer anticipated the need for a more complex architecture. For example, a poltergeist arises if the same method acts as both the client and invoker in a command pattern, and the programmer anticipates separating the two phases. However, this more complex architecture may actually never materialize.

Poltergeists should not be confused with long-lived, state-bearing objects of a pattern such as model–view–controller, or tier-separating patterns such as business delegate pattern.

To remove a poltergeist, delete the class and insert its functionality in the invoked class, possibly by inheritance or as a mixin.

There have been proposed methods in detecting poltergeists in code for refactoring. [1]

See also

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References

  1. ↑ Al-Rubaye, Samer Raad Azzawi; Selcuk, Yunus Emre (24–26 November 2017). "An investigation of code cycles and Poltergeist anti-pattern". 2017 8th IEEE International Conference on Software Engineering and Service Science (ICSESS). pp. 139–140. doi:10.1109/ICSESS.2017.8342882. ISBN   978-1-5386-0497-7.


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