Abstraction inversion

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article may contain excessive or irrelevant examples. Please help improve the article by removing less pertinent examples. (October 2013) This article possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (May 2009) (Learn how and when to remove this message) (Learn how and when to remove this message)

In computer programming, abstraction inversion is an anti-pattern arising when users of a construct need functions implemented within it but not exposed by its interface. The result is that the users re-implement the required functions in terms of the interface, which in its turn uses the internal implementation of the same functions. This may result in implementing lower-level features in terms of higher-level ones, thus the term 'abstraction inversion'.

Possible ill-effects are:

• The user of such a re-implemented function may seriously underestimate its running-costs.
• The user of the construct is forced to obscure their implementation with complex mechanical details.
• Many users attempt to solve the same problem, increasing the risk of error.