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. The book includes examples in C++ and Smalltalk.
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. The authors are often referred to as the Gang of Four (GoF).
Patterns by Type
1. Creational pattern
Creational patterns are ones that create objects for you, rather than having you instantiate objects directly. This gives your program more flexibility in deciding which objects need to be created for a given case.
These concern class and object composition. They use inheritance to compose interfaces and define ways to compose objects to obtain new functionality.
Most of these design patterns are specifically concerned with communication between objects.