Paul Czubilinski wrote:
Hello,
I have a problem with code like this (PHP 5.1.4):
fila A.php:
=======
include(B.php);
class document extends obj {
.........
}
file B.php:
=======
$GLOBALS['x']->new we();
function __autoload($cla ss_name) {
...here is the code to load classes...
}
file C.php
=======
class we extends obj {
private $document;
function __construct() {
$this->document = new document();
}
}
The problem is that after loading A.php into browser, PHP cannot find
document class which is defined in the A.php file! The problem is even
more strange - if document class doesnt extends obj class than
everything is ok.
(The problem exact is that __autoload special function is called when
in file C.php constructor of class we try to make the document object
(all other classes like obj has been already loaded).
Do you have any idea what is wrong with that?
There are limits to PHP's ability to resolve class cross-dependency. I
think you might have bumped into one. I can't quite figure out the load
order of the classes in your example, but I suspect the problem has
something to do with class autoloading. When a class is defined outside
any runtime directives (such as a function), PHP tries to resolve a
class at compile time as well as runtime. Consider the following:
class A extends B {
}
class B {
}
When PHP first encounter A at compile time, there is no way for it to
resolve the class, as it hasn't seen B yet. So it quietly skips over
it, moving on to the definition of B. When PHP runs the code in global
scope, it'll try to resolve A again. This time, B is defined, so
everything is okay.
The situation changes when the definitions are inside a function:
function dingo() {
class A extends B {
}
class B {
}
}
As the function might never be called, PHP cannot resolve either class
at compile time. Both A and B have to be resolved at runtime. Because A
is declared before B, PHP will try to resolve it first--and fail.
