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Date: Fri, 19 Oct 2007 22:42:02 -0400
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Subject: Order of class resolution with namespaces and autoload
From: chuck@horde.org (Chuck Hagenbuch)

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Hi folks-

I've hit upon something with namespaces and autoloading that I think =20
is a little out of order. If you take the attached 3 files, put them =20
in the same directory, and run demo.php, you will see this:

Fatal error: Uncaught exception 'Exception' in /Users/chuck/Desktop/test.php=
:7


If you look at the code, test.php defines a Test:: namespace with a =20
Tester class that throws an exception, test_exception.php provides an =20
Exception derivative (Test::Exception) for that namespace, and =20
demo.php includes test.php, sets up an __autoload function to load the =20
exception class, and triggers the exception throwing code.

However autoload is never called and the exception is of type =20
::Exception, because the class resolution order seems to look like this:

- does the class exist (_already defined_) in the current namespace?
- does the class exist in the global (non-prefixed or "::") namespace?
- then try autoload

What I think should happen is:

- does the class exist in the current namespace?
- can the class be autoloaded with the current namespace?
- does the class exist in the global scope
- global autoload

Otherwise if you are re-defining a global class, which I imagine will =20
be quite common with Exception at least, you will have to explicitly =20
load your Exception classes or they'll never be used.

The other alternative would be to say that if you want to use a global =20
class inside a namespace you MUST prefix it with ::. I think this is =20
reasonable since if you have a namespaced file it's already not going =20
to work with anything before PHP 5.3, and that would remove the two =20
potential autoload checks.

Thanks,
-chuck
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<?php

include './test.php';

function __autoload($class) {
    include './test_exception.php';
}

$tester = new Test::Tester();
$tester->fail();

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<?php

namespace Test;

class Tester {
    public function fail() {
        throw new Exception();
    }
}

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<?php

namespace Test;

class Exception extends ::Exception {
}

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