Poltergeist (computer programming)
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:
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.
See also
References
- Brown, William J. (1998). "Chapter 5: Software Development AntiPatterns". AntiPatterns: Refactoring Software, Architectures, and Projects in Crisis. New York, USA: John Wiley & Sons. ISBN 0-471-19713-0.