php 什么是php中的自动加载？
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What is autoload in php?
提问by DEVOPS
what is autoload in PHP?
PHP 中的自动加载是什么？
采纳答案by osm
This will be of help to you about usage of autoload. http://ditio.net/2008/11/13/php-autoload-best-practices/
这将有助于您了解自动加载的使用。http://ditio.net/2008/11/13/php-autoload-best-practices/
It's a magic function that helps you include / require files using class name.
这是一个神奇的功能，可以帮助您使用类名包含/需要文件。
function __autoload($class_name)
{
require_once $DOCUMENT_ROOT . “/classes/” . $class_name .“.php”;
}
It's deprecated at PHP 7.2.0 and spl_autoload_register is recommended for that purpose.
它在 PHP 7.2.0 中已被弃用，为此推荐使用 spl_autoload_register。
回答by Muhammad Shahzad
What is autoloading?
什么是自动加载？
Every time you want to use a new class in your PHP project, first you need to include this class (using include or require language construct, that's right this are not functions). However if you have __autoload function defined, inclusion will handle itself.
每次你想在你的 PHP 项目中使用一个新类时，首先你需要包含这个类（使用 include 或 require 语言构造，没错，这不是函数）。但是，如果您定义了 __autoload 函数，则包含将自行处理。
include "classes/class.Foo.php";
$foo = new Foo;
$foo->start();
$foo->stop();
Basic Autoloading Example
基本自动加载示例
function __autoload($class_name)
{
require_once $DOCUMENT_ROOT.“classes/class.”.$class_name.“.php”;
}
$foo = new Foo;
$foo->start();
$foo->stop();
Update
更新
PHP 5 introduced the magic function __autoload() which is automatically called when your code references a class or interface that hasn't been loaded yet.
PHP 5 引入了魔术函数 __autoload() ，当您的代码引用尚未加载的类或接口时会自动调用该函数。
The major drawback to the __autoload()function is that you can only provide one autoloader with it. PHP 5.1.2 introduced spl_autoload()which allows you to register multiple autoloader functions, and in the future the __autoload()function will be deprecated.
该__autoload()功能的主要缺点是您只能提供一个自动加载器。PHP 5.1.2 引入了spl_autoload()它允许您注册多个自动加载器函数，将来该__autoload()函数将被弃用。
The introduction of spl_autoload_register()gave programmers the ability to create an autoload chain, a series of functions that can be called to try and load a class or interface. For example:
引入spl_autoload_register()使程序员能够创建自动加载链，这是一系列可以调用以尝试加载类或接口的函数。例如：
<?php
function autoloadModel($className) {
$filename = "models/" . $className . ".php";
if (is_readable($filename)) {
require $filename;
}
}
function autoloadController($className) {
$filename = "controllers/" . $className . ".php";
if (is_readable($filename)) {
require $filename;
}
}
spl_autoload_register("autoloadModel");
spl_autoload_register("autoloadController");
回答by slikts
Here is the official documentation: http://php.net/autoload
这是官方文档：http: //php.net/autoload
In short, it just allows you to define search paths for classes so you wouldn't be required to include the files containing them manually.
简而言之，它只允许您定义类的搜索路径，因此您不需要手动包含包含它们的文件。
I suggest you should develop a habit of searching php.net by just appending function names or obvious keywords to the address. That's how I found php.net/autoload. It's quite convenient like that.
我建议你应该养成搜索 php.net 的习惯，只需在地址后附加函数名称或明显的关键字。这就是我找到 php.net/autoload 的方式。这样倒是挺方便的。
回答by kumardippu
an __autoload()
//function which is automatically called in case you are trying to use
//a class/interface which hasn't been defined yet.
function __autoload($class_name) {
include $class_name . '.php';
}
