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Design patterns in Object oriented analysis and design
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- 3. DEFINITION A design patternprovides a general reusable solution to a common design problem. • well-tested solutions to common problems • Useful solution • Reusable • Contextual
- 4. USES OF DESIGNPATTERNS • Helps to prevent subtle issues • Design patterns can be improved over time • Design patterns provide : – General solutions – Documented in a format that doesn’t require specifics tied to a particular problem.
- 5. CATEGORIES 1) Creational 1) Thesedesign patterns are all about class instantiation. 2) class-creation patterns use inheritance. 3) object-creation patterns use delegation effectively to get the job done. 2) Structural 1) All about Class and Object composition. 2) Structural object-patterns define ways to compose objects to obtain new functionality. 3) Behavioral 1) All about Class’s objects communication. 2) those patterns that are most specifically concerned with communication between objects.
- 6. CREATIONAL DESIGN PATTERNS •Abstract Factory Creates an instance of several families of classes • Builder Separates object construction from its representation • Factory Method Creates an instance of several derived classes • Object Pool Avoid expensive acquisition and release of resources by recycling objects that are no longer in use • Prototype A fully initialized instance to be copied or cloned • Singleton A class of which only a single instance can exist
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- 9. STRUCTURAL DESIGN PATTERNS •Facade A single class that represents an entire subsystem • Flyweight A fine-grained instance used for efficient sharing • Private Class Data Restricts accessor/mutator access • Proxy An object representing another object • Adapter Match interfaces of different classes • Bridge Separates an object’s interface from its implementation • Composite A tree structure of simple and composite objects • Decorator Add responsibilities to objects dynamically
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- 12. BEHAVIORAL DESIGN PATTERNS •Null Object Designed to act as a default value of an object • Observer A way of notifying change to a number of classes • State Alter an object’s behavior when its state changes • Strategy Encapsulates an algorithm inside a class • Template method Defer the exact steps of an algorithm to a subclass • Visitor Defines a new operation to a class without change • Chain of responsibility A way of passing a request between a chain of objects • Command Encapsulate a command request as an object • Interpreter A way to include language elements in a program • Iterator Sequentially access the elements of a collection • Mediator Defines simplified communication between classes • Memento Capture and restore an object’s internal state
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- 15. THANK YOU SO MUCHALL OF YOU GYZ..