Design patterns primer
The concepts of design patterns first appeared in the book A Pattern Language: Towns, Buildings, Construction (Christopher Alexander,1977). Influenced by this, in 1987, Kent Beck and Ward Cunningham authored a paper on using pattern languages for object-oriented design. While this kicked off the discussion on design patterns, it became mainstream with the publication of the book Design Patterns: Elements of Reusable Object-Oriented Software (Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, 1995 – Addison-Wesley Professional). The authors are popularly referred to as The Gang of Four and the book is called the Gang of Four book.
The Gang of Four book divided design patterns into three categories. The categorizations were based on the life cycle and interaction of objects. They are creational, structural, and behavioral design patterns. There are a total of 23 design patterns under these categories. The following tables show the design patterns...
