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Subject: Re: [PHP-DEV] Re: SPLClassLoader RFC Thoughts And Improvements
From: davidkmuir@gmail.com (David Muir)

On 11/11/2011 01:31 PM, guilhermeblanco@gmail.com wrote:
> Hi Anthony,
>
> Thanks immensely for your input.
> Without such action, it's extremely hard to improve the RFC. =)
> Awesome action from your side.
> I'll place my comments inline.
>
> On Thu, Nov 10, 2011 at 1:26 PM, Anthony Ferrara <ircmaxell@gmail.com> wrote:
>

...snip...

>>  b) The code that includes the file should be changed to require_once
>> to eliminate including the same file twice when different classes map
>> to the same file.  For example, this should not fail (assuming both
>> classes are not in the same file):
>>
>>        new \Foo\Bar\Baz;
>>        new \Foo\Bar_Baz;
>>
>>        Both map to the same file, but are distinct classes in PHP.
>> By changing it to require_once, it'll realize it already included the
>> file and then skip over that and let another class have its shot.
>>
> Actually they do not map the same file. Here is the path of each one:
> new \Foo\Bar\Baz; => [path]/Foo/Bar/Baz.php
> new \Foo\Bar_Baz; => [path]/Foo/Bar_Baz.php
>
> You may now be in doubt if PEAR1 style is supported. Yes, it is. The
> point is that code detects for the presence of namespace separator and
> if it is found, it considers the namespace separator as directory
> separator; if not, it considers the "_" char as directory separator.
> We decided that because PEAR1/Zend1/Doctrine1/Symfony1 (and many
> others) would not be supported if we didn't do that way. It's the
> solution for BC. Since most of the mentioned ones are already in
> another major version, consuming PHP 5.3 namespaces, then the default
> behavior would work nifty. =)

This is news to me, and even the RFC states:
Each “_” character in the CLASS NAME is converted to a
DIRECTORY_SEPARATOR. The “_” character has no special meaning in the
namespace.

I believe you're confusing it with the namespace portion:
new \Foo_Bar\Baz; => [path] /Foo_Bar/Baz.php
in which case the _ is retained.
Otherwise:
new \Foo\Bar_Baz; => [path] /Foo/Bar/Baz.php
new \Foo_Bar\Baz_Waz => [path] /Foo_Bar/Baz/Waz.php

If what you are saying is true, then the RFC is incorrect, and should be
updated to included the correct rules.

>
> Regarding the require_once change, it's not really needed. The reason
> is because class loading would never be triggered again if the
> class/trait/interface is already loaded. The require_once is extremely
> slow than require due to this check.
> But I really don't have strong feelings to change that is many people
> find it necessary.

That was true 6 years ago. Benchmarks from 4 years ago, it was the other
way around. Has it flipped back again?

...snip...

>> 4. The RFC should avoid implementing any pattern or style that may
>> make future feature addition difficult or pose risks towards such.  An
>> example would be implementing an interface for the autoloader which
>> defines something like load($class).  The problem there is that if
>> function autoloading is added, the interface won't be able to support
>> it.  So it's stuck in a hard place between changing an implemented
>> interface (which will bork code significantly on update) and adding a
>> new interface (which would be the lesser of evils, but would just add
>> to the deprecated cruft).
> OO theory defines that whenever you want to have a contract to be
> followed by any implementation, an interface is required.
> The contract is something useful that enforces that way you receive
> would have at least what it was expected/used internally.
> So, if we agree in the future that the chosen implementation would not
> contain the methods ->register/->unregister, and spl_autoload_register
> would accept SplAutoload instances, then the contract is more than
> required.
> Regarding the function autoloading, as I discussed previously, it is
> invalid in this paradigm.
> I don't see how the contract would change in the future.

But the only contract that is needed by spl_autoload_register is the
load method.

The register and unregister methods are not needed by any other entity
that I am aware of, and are only there as convenience methods for the
user, and therefore don't belong in the interface for a generic
autoloader. A second interface could be added for self-registering
autoloaders, but that begs the question, why should an autoloader know
how to register itself with a particular loading stack (sure the spl
autoloading stack is the only one we have, but still...)? There's no
discussion in the RFC showing why those methods should be part of an
autoloader interface.
The same applies to the setMode() and add() methods. What contract are
they fulfilling?

Cheers,
David