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Date: Thu, 14 Mar 2013 12:26:31 -0400
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To: PHP internals <internals@lists.php.net>
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Subject: static type-references
From: rasmus@mindplay.dk (Rasmus Schultz)

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Hey List,

What do you think about adding a typeof() operator to PHP?

It could go something like this:

    class User
    {
        public $name;
    }

    /**
     * @var ReflectionClass $user_type
     * @var ReflectionProperty $user_name_property
     */

    $user_type = typeof(User);

    $user_name_property = typeof(User::$name);

Mind you, this is an operator and not a function - User and User::$name are
interpreted as symbols.

This would allow for static analysis of class and property-references.

Why? Because you can't use static analysis on code like this:

    $user_type = new ReflectionClass('User');

    $user_name_property = new ReflectionProperty('User', 'name');

'User' and 'name' are just strings, and strings are dead matter when it
comes to static analysis.

Most form builders and ORMs (and other reflective meta-programming
components) require references to properties or classes, e.g.:

    $form->textInputFor($user, 'name');

There is no knowledge that 'name' actually refers to the symbol User::$name
and hence to way to perform static analysis or use refactoring tools on
this code.

Compare to:

    $form->textInputFor($user, typeof(User::$name));

This code can be analyzed and refactored, because the reference to the
User::$name property is now literal.

Actually having to type out typeof() may not be the most elegant approach,
and using this syntax it does resemble a function - having a more distinct
syntax might be better.

But those things aside, what do you think about having a way to statically
reference types and members?

Thanks,
   Rasmus Schultz

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