Why Design Patterns ?
In software engineering, a design pattern is a general repeatable solution to a commonly occurring problem in software design. A design pattern isn't a finished design that can be transformed directly into code. It is a description or template for how to solve a problem that can be used in many different situations.
In most of the object oriented languages some common problems are solved with design patterns viz.. singleton, proxy, object pool etc....
It can roughly classified into the following
1. Creational
2. Structural
3. Behavioural
1. Creational
This design patterns is all about class instantiation. This pattern can be further divided into class-creation patterns and object-creational patterns.
Major types of creational patterns are
This design patterns is all about Class and Object composition. Structural class-creation patterns use inheritance to compose interfaces
Major types are
This design patterns is all about Class's objects communication. Behavioral patterns are those patterns that are most specifically concerned with communication between objects.
In software engineering, a design pattern is a general repeatable solution to a commonly occurring problem in software design. A design pattern isn't a finished design that can be transformed directly into code. It is a description or template for how to solve a problem that can be used in many different situations.
In most of the object oriented languages some common problems are solved with design patterns viz.. singleton, proxy, object pool etc....
It can roughly classified into the following
1. Creational
2. Structural
3. Behavioural
1. Creational
This design patterns is all about class instantiation. This pattern can be further divided into class-creation patterns and object-creational patterns.
Major types of creational patterns are
- 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
This design patterns is all about Class and Object composition. Structural class-creation patterns use inheritance to compose interfaces
Major types are
- 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
- 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
This design patterns is all about Class's objects communication. Behavioral patterns are those patterns that are most specifically concerned with communication between objects.
- 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
- 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
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