A guide to choosing PHP design patterns

Guidelines for Choosing PHP Design Patterns

A design pattern is a predefined solution to common programming problems. They are designed to improve code reusability, scalability, and maintainability.

Principles for selecting design patterns

• Problem domain:Design patterns map to specific problem domains.
• Code duplication:Design patterns help reduce code duplication.
• Extensibility:Design patterns make the code easier to extend or modify.
• Maintainability:Design patterns improve the maintainability of code, making it easy to read and understand.

Common PHP design patterns

Creative

• Factory method:Create an object without specifying the specific class of the object.
• Single case mode:Ensure that a class can only have one instance.
• Builder Mode:Create complex objects step by step and easy to customize.

Structural

• Adapter pattern:Enables incompatible objects to work together.
• Bridge mode:Separate the abstract part from the implementation part to improve scalability.
• Combined mode:Group objects into a tree structure to represent the part-whole hierarchy.

Behavioral

• Strategy mode:Change certain behaviors of the object based on different algorithms or strategies.
• Observer mode:When the subject state changes, the observer will automatically receive a notification.
• Chain of responsibility mode:Process the request along the chain of responsibility until an object can handle it.

Practical case: singleton mode

Suppose you are creating an e-commerce website and need a logging class responsible for writing log files. To ensure that there is only one log file, you can use the singleton mode:

class Logger { private static $instance; private $handle; private function __construct() { $this->handle = fopen('log.txt', 'a'); } public static function getInstance() { if (!isset(self::$instance)) { self::$instance = new Logger(); } return self::$instance; } public function write($message) { fwrite($this->handle, $message . "\n"); } public function close() { fclose($this->handle); } } // 使用单例类 $logger = Logger::getInstance(); $logger->write('商品添加成功'); $logger->close();

Using the singleton mode, no matter how many requests there are in the website, there is always only one instance of the log file.

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