Concept of singleton pattern
The singleton pattern refers to a design pattern in which a class has only one object instance in the entire application.
Characteristics of the singleton pattern
A class has only one instance in the entire application
The class must create this instance by itself
You must provide this instance to the entire system by yourself
The reason for using the singleton mode in PHP
Most of my operations in PHP involve dealing with various databases, including mysql, redis, Memcache and other relational and non-relational databases, so there will be a large number of operations to connect to the database in an application. If the singleton mode is not used, new operations will be required every time, but each new will consume a lot of memory resources and system resources, and every time a database connection is opened and closed, it is a great test and waste of the database.
Need a static member variable that holds the only instance of the class (usually $instance is a private variable)
Constructors and clone functions must be declared private , in order to prevent the new class of external programs from losing the meaning of the singleton mode
A public static method must be provided to access this instance, thereby returning a reference to the only instance
//设计模式 //单例模式 都是使用同一个对象 //class Ren //{ // public $name; // private static $dx; //存储对象 // // private function __construct() // { // // } // // public static function DuiXiang() // { // if(empty(self::$dx)) // { // self:;$dx=new Ren(); // } // return self::$dx; // } //} // //$r= Ren::DuiXiang(); //把构造函数变为私有 //做了一个方法来间接造对象 //在该方法里面加限制
Factory class
refers to a class that contains a method specifically used to create other objects. The factory class is crucial in the practice of polymorphic programming, which allows dynamic replacement of classes. , modifying the configuration usually makes the application more flexible, and it is important for advanced PHP developers to be proficient in the factory mode.
The factory pattern is usually used to return different classes that conform to similar interfaces. A common use of factories is to create polymorphic providers, allowing us to decide which ones should be instantiated based on application logic or configuration settings. A class, for example, can be extended using such a provider to use the new extended name without the need to refactor other parts of the application.
Usually, the factory pattern has a key construct, which is a static method named Factory according to the general principle. However, this is just a principle. The factory method can be named arbitrarily. This static method can also accept parameters of any data. It must be Return an object.
class YunSuan { public $a; public $b; function Suan() { echo "对两个数进行运算"; }
class gongchang { //功能 : 给一个参数,返回一个对象 static function chanpin($name) { switch($name) { case "'+": return new jia(); break; case "-"; return new jian(); break; } } } $a=gongchang::chanpin("+");
For more articles related to singleton mode and factory mode in PHP, please pay attention to the PHP Chinese website!

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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