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Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Design Patterns: Elements of Reusable Object-Oriented Software is a software engineering book describing software design patterns.
The book’s authors are Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides with a foreword by Grady Booch. The book is divided into two parts, with the first two chapters exploring the capabilities and pitfalls of object-oriented programming, and the remaining chapters describing 23 classic software design patterns. It has been influential to the field of software engineering and is regarded as an important source for object-oriented design theory and practice. More than 500,000 copies have been sold in English and in 13 other languages.
OOPSLA ’90, “Towards an Architecture Handbook”, run by Bruce Anderson, where Erich Gamma and Richard Helm met and discovered their common interest. They were later joined by Ralph Johnson and John Vlissides. The original publication date of the book was October 21, 1994 with a 1995 copyright, hence it is often cited with a 1995-year, despite being published in 1994.
The book was first made available to the public at the OOPSLA meeting held in Portland, Oregon, in October 1994. In 2005 the ACM SIGPLAN awarded that year’s Programming Languages Achievement Award to the authors, in recognition of the impact of their work “on programming practice and programming language design”.
As of March 2012, the book was in its 40th printing. Program to an ‘interface’, not an ‘implementation’. Composition over inheritance: “Favor ‘object composition’ over ‘class inheritance’.
Use of an interface also leads to dynamic binding and polymorphism, which are central features of object-oriented programming. The authors refer to inheritance as white-box reuse, with white-box referring to visibility, because the internals of parent classes are often visible to subclasses. Because inheritance exposes a subclass to details of its parent’s implementation, it’s often said that ‘inheritance breaks encapsulation'”.