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 1996 - Object World West Conference: "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 antipattern 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. To remove a poltergeist, delete the class and insert its functionality in the invoked class, possibly by inheritance or as a mixin. See also Anti-pattern Factory (object-oriented programming) YAGNI principle References External links Development AntiPatterns Anti-patterns