note 58488 deleted from language.oop5.autoload by joey
| From: | joey@php.net | Date: | Thu, 05 Jan 2012 15:29:34 +0000 |
| Subject: | note 58488 deleted from language.oop5.autoload by joey | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-185372@lists.php.net to get a copy of this message | ||
Note Submitter: quetzalcoatl(AT)poczta.fm
----
While __autoloading is a nice feature, one can stumble upon small problem with it. Imagine:
file A.php:
<?
function __autoload($cname)
{ require_once "include/$cname.php";}
}
B::testC();
?>
file B.php:
<?
function __autoload($cname)
{ require_once "include/$cname.php";}
}
class B
{ public static function test()
{ C::testMe();
}
}
?>
file C.php:
<?
class C
{ public static function testMe()
{ print("OK!");
}
}
?>
Now, running file A.php will result in an error.. because from A's point of view, function
__autoload is declared twice - once in A.php, and in required_once'd B.php, too! [Not
mentioning that C.php and many many many other required or included files could use it too :) ] So,
of course we can remove the duplicate __autoload functions from B.php and any other required files.
Thus, we either disallow usage of B.php independently (and other required-able/include-able files!)
, as without the __autoload it can not work -- or we have to manually require_once its dependecies,
thus making manually the job of __autoload. Irritating, isn't it?
A simple trick can help us here. Every file you would place an __autoload function, place instead
something like:
if(!function_exists("__autoload"))
{ //your __autoload declaration, for example:
function __autoload($cname)
{ require_once "include/$cname.php";
}
}
When I first tried it, I was really surprised that you can control functions' declaration with
simple IF, without any evals or other tricks.
Well.. it's probably a basic "trick", but I didn't notice it anywhere. Feel free
to remove it if it was already posted somewhere:)