PHP design pattern - UML class diagram_PHP tutorial

Foreword
I have been developing with PHP for more than two years, and I am going to write about commonly used design patterns, all based on my own practical experience. Of course, you must first understand design patterns before using them, so here I will first explain the UML class diagram. Through UML class diagrams, you can better communicate with everyone and express your design ideas easily

UML
Unified Modeling Language (UML), also known as Unified Modeling Language or Standard Modeling Language, is an OMG standard started in 1997. It is a graphical language that supports modeling and software system development, providing models for all stages of software development. and visualization support, including requirements analysis, specification, construction and configuration

Class
The rectangular box represents a class, and the class diagram is divided into three layers
The first level is the name of the class. If it is an abstract class, the class name is in italics, such as the animal class in the picture
The second layer is the characteristics of the class (usually the member attributes of the class)
The third level is class operations (usually member methods of the class)
Note: "+" represents public, "-" represents private, and "#" represents protected

The animal class is an abstract class, it cannot be instantiated, but humans can be instantiated

Interface
There are two representation methods for interfaces: rectangle representation (the interface for driving) and lollipop representation (the interface for driving in humans).
Rectangular notation, with <> or <> at the top, the first line is the interface name, the second line is the interface method
Lollipop notation, next to the circle is the interface name, the interface method appears in the implementation class, if a human drives a car

Generalization
Represents the inheritance relationship between classes, the inheritance relationship between interfaces, or the implementation relationship between classes and interfaces. The generalized relationship is from the subclass to the parent class, as opposed to inherited or implemented methods. Use hollow triangle + solid line to represent inheritance. In the static structure diagram, drag and drop the inductive connection between the parent class and the child class, with the arrow pointing to the parent class and the other pointing to the child class. Use hollow triangle + dotted line to represent the implementation interface.

Dependency
For two relatively independent objects, when one object is responsible for constructing an instance of the other object, or depends on the services of the other object, the dependency relationship between the two objects is mainly reflected. Dependencies are embodied in local variables, method parameters, and calls to static methods. For example, animals have several major characteristics, such as metabolism, reproduction, and life. To be alive, animals need oxygen, water, and food, which means animals depend on oxygen and water.
Code performance
Local variables, method parameters, or calls to static methods

Aggregation
The aggregation relationship is the relationship between the whole and the parts, and the parts can exist independently of the whole. If the relationship between the car and the tires is a whole and a part, the tires can still exist without the car. Represented by a solid line with a hollow diamond

Code performance
Member variables

Composition
It is the relationship between the whole and the parts, but the parts cannot exist alone without the whole. For example, the company and the part are in a combined relationship

Code performance
Member variables

Postscript
There are still some things to be added, so remember as you learn!