Backend Development
PHP Tutorial
What are php closures? Detailed explanation of closure usage examples
What are php closures? Detailed explanation of closure usage examples
This article mainly introduces PHP Detailed explanation of closure and related information of example code. Friends who need it can refer to
closure and anonymous function in Introduced in PHP5.3.0.
A closure refers to a function that encapsulates the surrounding state when created. Even if the environment in which the closure is located no longer exists, the state encapsulated in the closure still exists.
Theoretically, closures and anonymous functions are different concepts. But PHP treats it as the same concept.
In fact, closures and anonymous functions are objects disguised as functions. They are instances of Closure class.
Closures, like strings and integers, are first-class value types.
Create closure
<?php
$clousre = function ($name) {
return 'Hello ' . $name;
};
echo $closure('nesfo');The reason why we can call the $closure variable is because the value of this variable is a closure, and the closure object implements Invoke()Magic method. As long as there is () after the variable name, PHP will find and call the invoke() method. PHP closures are usually used as callbacks of functions. array_map(), preg_replace_callback() methods will use callback function. This is the best time to use closures!
For example:
<?php
$numbersPlusOne = array_map(function ($number) {
return $number + 1;
}, [1, 2, 3]);
print_r($numbersPlusOne);Get the result:
[2, 3, 4]
Before the closure appears , you can only create a named function individually and then reference that function by name. By doing this, the code execution will be slightly slower, and the implementation of the callback will be isolated from the usage scenario.
<?php
function incrementNum ($number) {
return $number + 1;
}
$numbersPlusOne = array_map('incrementNum', [1, 2, 3]);
print_r($numbersPlusOne);Attach state
Anonymous functions can not only be used as callbacks, but can also be attached to and encapsulated states for PHP.
In PHP, you must manually call the bindTo() method of the closure object or use the use keyword to attach the state to the PHP closure.
<?php
function enclosePerson ($name) {
return function ($doCommand) use ($name) {
return $name . ', ' . $doCommand;
}
}
$clay = enclosePerson('Clay');
echo $clay('get me sweet tea!');Get the result:
"Clay, get me sweet tea!"
PHP closures are objects, and each closure instance can Use the $this keyword to get the internal state of a closure. The default state of the closure object is useless, only the invoke() method and the bindTo method.
We can use the bindTo() method to bind the internal state of the Closure object to other objects.
The second parameter of the bindTo() method: Its function is to specify the PHP class to which the object of the binding closure belongs. Therefore, a closure can access protected and private members of the object to which the closure is bound.
PHP frameworks often use the bindTo() method to map routing URLs to anonymous callback functions. This allows you to use the $this keyword in this anonymous function to reference important application objects.
Use bindTo() method to attach closure status
<?php
class App
{
protected $routes = [];
protected $responseStatus = '200 OK';
protected $responseContentType = 'text/html';
protected $responseBody = 'Hello world';
public function addRoute($routePath, $routeCallback){
$this->routes[$routePath] = $routeCallback->bindTo($this, CLASS);
}
public function dispatch($currentPath){
foreach($this->routes as $routePath => $callback){
if ($routePath === $currentPath) {
$callback();
}
}
header('HTTP/1.1' . $this->responseStatus);
header('Content-type: ' . $this->responseContentType);
header('Content-length' . mb_strlen($this->responseBody));
echo $this->responseBody;
}
}<?php
$app = new App();
$app->addRoute('/user/nesfo', function () {
$this->responseContentType = 'application/json; charset=utf8';
$this->responseBody = '{"name": "nesfo"}';
});
$app->dispatch('/user/nesfo');The above is the detailed content of What are php closures? Detailed explanation of closure usage examples. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati
7 PHP Functions I Regret I Didn't Know Before
Nov 13, 2024 am 09:42 AM
If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c
Explain JSON Web Tokens (JWT) and their use case in PHP APIs.
Apr 05, 2025 am 12:04 AM
JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,
PHP Program to Count Vowels in a String
Feb 07, 2025 pm 12:12 PM
A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total
How do you parse and process HTML/XML in PHP?
Feb 07, 2025 am 11:57 AM
This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an
Explain late static binding in PHP (static::).
Apr 03, 2025 am 12:04 AM
Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.
What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases?
Apr 03, 2025 am 12:03 AM
What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
