One design pattern per day (1)-Overview

Preface

I have summarized the design patterns recently. This article will give you an overall introduction to the design patterns.

Body 1. Definition

The design pattern is a code design solution for a specific type of problem. It is a summary of the experience in code design.

2. Role

• Improve code reuse rate and reduce development costs and cycles
• Improve code maintainability and scalability
• Make the code more elegant and readable
• Make code easier to be understood by others

3. Design Principles

The following object-oriented design principles must be observed when designing a design pattern:

• Single Responsibility Principle(SRP): For a class, there should be only one reason for its change.
• Principle of opening/closing(ASD): Classes, modules, and functions can be expanded, but cannot be modified.
• Rys replacement principle(LSP): All objects that reference the base class (parent class) must be transparently used.
• Dependency inversion principle(DIP): High-Level modules should not depend on low-level modules. Both of them should depend on abstraction. Abstraction should not depend on details, but on abstraction.
• Dumit principles(LOD): A software entity should interact with other entities as little as possible.
• Interface isolation principle(ISP): The dependency of one class on another class should be built on the smallest interface.

4. Design Pattern Classification

Common23TypeDesign ModeIn general, there are three categories:Creation Mode,Structural ModeAndBehavior mode.

Creation ModeFive methods: Factory method mode, abstract factory mode, Singleton mode, builder mode, and prototype mode.

Structural Mode(7 in total): adapter mode, decorator mode, proxy mode, appearance mode, bridging mode, combination mode, and meta mode.

Behavior mode(11 in total ): rule mode, template method mode, observer mode, iteration sub-mode, responsibility chain mode, command mode, memorandum mode, state mode, visitor mode, intermediary mode, interpreter mode.

Shows the three types of design patterns and their classifications:

Summary

This article gives a general introduction to the definition of design patterns. Next I will analyze several common design patterns in detail.

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One design pattern per day (1)-Overview