Introduction to Design Patterns 
            !" 2003 - 2007 DevelopIntelligence 
           What is a Pattern? 
           ! " There are many definitions for a pattern: 
               ! " A model or design used as a guide 
               ! " A set of instructions to be followed when implementing something 
               ! " An example for others to follow 
               ! " A decorative design 
           ! " Where do patterns exist? 
               ! " In arts and crafts (think quilts) 
               ! " In buildings and architecture  
               ! " In manufacturing (think models and production) 
               ! " In leadership (think of followers modeling a leader) 
               ! " In software 
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            History of Design Patterns 
            ! " Concept of design patterns originated as an architectural 
                concept by Christopher Alexander in 1977 
            ! " Introduced into the programming community in 1987 by 
                Ward Cunningham and Kent Beck 
                 ! " Focused on apply design pattern concept to software 
                 ! " Applied the concept using the SmallTalk language 
                 ! " Released a paper at OOPSLA 87 called “Using pattern languages 
                    for object-oriented programmers” 
            ! " Gained popularity in the 90s  
                 ! " Result of “Design Patterns: Elements of Reusable Object-Oriented 
                    Software” book written by Gamma, Helm, Johnson, and Vlissides 
                 ! " AKA: Gang of Four (GoF) book 
            ! " Have grown in popularity over time 
            !" 2003 - 2007 DevelopIntelligence 
            What is a Design Pattern? 
            ! " Term comes from work performed by architect 
                Christopher Alexander 
                 ! " Used to describe architectural solutions to reoccurring problems 
                 ! " Specifically, "Each pattern describes a problem which occurs over 
                    and over again in our environment, and then describes the core of 
                    the solution to that problem, in such a way that you can use this 
                    solution a million times over, without ever doing it the same way 
                    twice” 
            ! " Other definitions: 
                 ! " A identified and proven solution to a reoccurring problem in a 
                    specific context 
                 ! " A proven recipe describing how to solve a problem 
                 ! " A blue-print of how to solve a problem 
            !" 2003 - 2007 DevelopIntelligence