Design Patterns: Types

A design pattern is a reusable and general solution to a common software design

problem.It represents a blueprint for solving a particular class of problems in

a consistent and efficient manner. Design patterns provide a shared vocabulary

and a set of proven practices that enable software developers to communicate

more effectively, design robust and maintainable code, and avoid reinventing the

wheel for common challenges.

Design patterns capture the collective experience and expertise of software

designers and architects, offering solutions to recurring issues in software

design, such as structuring classes and objects, managing relationships between

components, and handling interactions between different parts of a system. They

help promote code that is modular, flexible, and easier to extend or modify over

time.

Design patterns are not code snippets or ready-made solutions that can be

directly copied into a project. Instead, they provide high-level descriptions of

the problem, the solution, and the context in which the pattern should be

applied. Developers need to adapt and implement the patterns according to the

specific requirements of their projects.

Design patterns are divided into three main categories:

creational, structural,and behavioral. Each category addresses a different

aspect of software design and helps solve specific design problems.

Here's a brief overview of the types of design patterns within each category:

Creational Design Patterns:

These patterns focus on object creation mechanisms, attempting to create objects

in a manner that suits the situation. Creational patterns provide control over

object instantiation.

Singleton: Ensures a class has only one instance and provides a global point of

access to that instance.

Factory Method: Creates objects without specifying the exact class of object

that will be created.

Abstract Factory: Creates families of related or dependent objects without

specifying their concrete classes.

Builder: Separates the construction of a complex object from its

representation, allowing the same construction process to create various

representations.

Prototype: Creates new objects by copying an existing instance, known as the

prototype.

Structural Design Patterns:

These patterns deal with object composition, creating relationships between

objects to form larger structures. Structural patterns provide ways to define

relationships between objects.

Adapter: Converts the interface of a class into another interface that clients

expect.

Bridge: Separates abstraction from its implementation, allowing both to evolve independently.

Composite: Composes objects into tree structures to represent part-whole

hierarchies.

Decorator: Adds behavior or responsibilities to individual objects dynamically,

without affecting other objects.

Facade: Provides a unified interface to a set of interfaces in a subsystem.

Flyweight: Shares objects to reduce memory consumption by allowing objects to

be reused instead of recreated.

Proxy: Provides a surrogate or placeholder for another object to control

access to it.

Behavioral Design Patterns:

These patterns deal with object collaboration and responsibilities, focusing

on how objects interact and communicate with each other. Behavioral patterns

provide solutions for object interaction and responsibilities.

Chain of Responsibility: Allows an object to pass a request along a chain of

potential handlers.

Command: Encapsulates a request as an object, allowing parameterization of

clients with different requests, queuing, and logging of requests.

Interpreter: Provides a way to evaluate language grammar or expressions.

Iterator: Provides a way to access elements of a collection sequentially

without exposing its underlying representation.

Mediator: Reduces the coupling between components by allowing them to

communicate through a central mediator.

Memento: Captures an object's internal state to be restored later, without

exposing its internal structure.

Observer: Defines a dependency between objects so that when one object changes

state, all its dependents are notified and updated automatically.

State: Allows an object to change its behavior when its internal state changes.

Strategy: Defines a family of algorithms, encapsulates each one, and makes

them interchangeable.

Template Method: Defines the structure of an algorithm in the base class but

lets subclasses override specific steps.

Visitor: Lets you add further operations to objects without having to modify

them.

Each design pattern is a valuable tool in a programmer's toolbox, offering

standardized solutions to common design problems and promoting software

that's easier to understand, maintain, and scale.