What are an Autoloading Classes in PHP?

[Flaco]

Hi friends,
I have just started with the PHP programming language. Since I am new to this language, I don't know much about it. I want to know about an auto-loading classes that are present in PHP. So I thought that someone hanging out there might be interested in helping me.!! Please explain me what are an Autoloading Classes in PHP? Any other useful information related to the topic would be appreciable.!!

[Solitario]

Many developers who create object-oriented applications, create a source file for class definition. The major drawback of this method is having to write a long list of includes file classes at the beginning of each script for an inclusion class. In PHP 5, this is no longer necessary. You can define the function __autoload () which will automatically be called if a class is not defined at the time of use. With it, you have one last chance to include a definition of class before PHP fails to declare a mistake. Hope that you understood the concept of the autoloading class.

[kyosang]

Prior to PHP 5.3.0, the exception thrown from the function autoload could not be intercepted by a block catch and caused a fatal error. Since PHP 5.3.0 +, they can be intercepted in wrestling, to an accuracy close: If you throw a custom exception, then the class of that exception must be available. autoload Function must be used recursively to automatically load the class of the custom exception. PHP 5 has an exception model similar to that of other programming languages. An exception can be thrown ( "throw") and caught ( "catch") in PHP. The code must be surrounded by a try block to facilitate the entry of potential exceptions.

[Viensterrr]

You should also keep in mind that autoloading is not available if using PHP in interactive mode CLI. The CLI SAPI was released for the first time with PHP 4.2.0, but it was experimental and had to be explicitly enabled with - enable-cli when running. / Configure script. The Windows packages between PHP 4.2.0 and PHP 4.2.3 distributed the CLI as php-cli.exe and let the CGI as php-cli.exe in the same directory. Since PHP 4.3.0 the Windows package distributes the CLI as php.exe in a separate folder named cli, so cli / php.exe. Since PHP 5, the CLI is installed in the main directory as php. exe. The CGI version is called when php-cgi.exe.

[MELTRONICS]

I have provided an example of the autoload (), that may help you in understanding more better :

<?php
function autoload($class_name) {
    require_once $class_name . '.php';
}
 
$obj  = new MyClassDemo1();
$obj2 = new MyClassDemo2(); 
?>

[CodGuru]

The following is an example for autoloading with exception handling for 5.3.0+, hope that helps you :

<?php
function autoloaddemo($name) {
    echo "Want to load $name.\n";
    throw new Exception("Not able to load $name.");
}
 
try {
    $obj = new NonLoadableClass();
} catch (Exception $e) {
    echo $e->getMessage(), "\n";
}
?>