Design Patterns

Design Patterns 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 […]

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Template Method

1. Usage Define the skeleton of an algorithm in base class “Template Method” Steps required concrete implementation define as placeholders in base class Derifed classes fill-up placeholders with concrete implementations […]

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State Pattern

1. Usage Allow an object to change behavior when State changed. implements OOP Final State Machine(FSM) 2. UML class diagram Context is wrapper class – interface to state Define abstract […]

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Observer pattern

1. Usage Pattern Observer – define relationship “one to many” such way that when state of object change all dependent objects notified/updated automatically. Pattern Observer encapsulate main component in Subject […]

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Strategy Pattern

1. Usage Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from the clients that use it. Capture the abstraction in […]

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Visitor Pattern

1. Usage Adds new operations to existing object structure without modifying that structure. Separates an algorithm from an object structure on which it operates. Example: An example would be a […]

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Command pattern

1. Usage Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations. The purpose of the Command pattern […]

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Iterator pattern

1. Usage Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation. makes possible to decouple collection classes and algorithms. Promote to “full […]

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Interpreter pattern

1. Usage Specialized database query languages such as SQL,RegExp. Specialized computer languages which are often used to describe communication protocols. Most general-purpose computer languages actually incorporate several specialized languages.(lua script […]

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Mediator pattern

1. Usage In software engineering, the mediator pattern defines an object that encapsulates how a set of objects interact. This pattern is considered to be a behavioral pattern due to […]

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