Re: RFC: about class names as values

I think doing something like this is a good idea for classes and interfaces. Ben. On 7/01/11 1:16 AM, Martin Scotta wrote:

Yes, my intention was to only add a magic constant with the class, similar to this namespace Bar { class Foo {

     const KLASS = __CLASS__;

} } namespace Buzz { use \Bar\Foo as BazFoo; class Bar extends BazFoo {

     const KLASS = __CLASS__;

} $bar = new Bar; $baz = new BazFoo; var_dump( get_class($baz), BazFoo::KLASS); var_dump( get_class($bar), Bar::KLASS ); } This is 100% valid PHP 5.3.3 code, but that includes a lot of effort from the developer. Someone miss to include the KLASS constant on a class and the result is undefined. If that PHP could add a magic constant --named CLASS or whatever you like-- to each class it will reduce the amount of class names hardcoded onto strings, probably to zero. The only issue that I found today is related to interfaces. I'm not sure if they should include this sort of magic constant, but I would rather include them just for consistency but, as I previously said, I'm not sure about this one. Martin Scotta 2011/1/5 John LeSueur<john.lesueur@gmail.com>

2011/1/5 Johannes Schlüter<johannes@php.net>

On Wed, 2011-01-05 at 21:53 -0300, Martin Scotta wrote:

$obj = newInstance( MyClass ); // notice. undefined constant MyClass

This describes the major change with your idea. What happens if a constant MyClass exists? Another question is something like this: <?php function factory($class) {

    return new $class();

} factory( SomeClass ); ?> To proper support this we'd have to make classes first class elements. For making this consistent it would make sense to make functions first class elements. And best drop the $ in front of variables and create a new language. Everything else becomes a mess. johannes -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php

I think he's actually proposing creating for each class the magic class constant CLASS, so your example becomes: <?php function factory($class) {

     return new $class();

} factory( SomeClass::CLASS ); ?> This is actually doable without a magic class constant, but requires a function or class constant to be declared in each class. <?php class SomeClass {

     const CLASS = __NAMESPACE__ . '\' . __CLASS__;
     static function getNameWithNSPath()
     {
         return __NAMESPACE__ . '\' . __CLASS__;
     }

} factory( SomeClass::getNameWithNSPath() ); ?> Perhaps this could be simplified with traits, if __NAMESPACE__ and __CLASS__ work in traits that way. In fact, that's an interesting question, what is __NAMESPACE__ in a trait defined in one namespace, then used in a class in a different namespace? I think the point is that the factory function could exist without any knowledge of the namespaces of the classes it would work on. Then, somewhere else where the class has been aliased or is otherwise accessible without the full namespace path, the developer wouldn't need to specify the full namespace path to the factory, but could ask the class itself what it's full namespace path was. I don't know that I agree with the idea, but I don't think it requires making classes first class elements. John