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Date: Sat, 23 Feb 2008 16:38:45 -0600
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Subject: Re: Trait aliasing syntax suggestions
From: spam.goes.in.here@gmail.com (Joshua Thompson)

>>> Another detail: The implementation of the parser changes should still
>>> allow a class or function called "trait", i.e. "trait" should only be a
>>> keyword at specific positions in the source to avoid unneccesary BC
>>> breaks. The current patch has this BC problem.
>>
>> This is not possible to implement, having tried to do a similar thing
>> for 'import' and 'namespace.'  The reason is that we can encounter a
>> classname at any point thanks to "classname::whatever" syntax, so it
>> slows the lexer down a bit in that for every T_TRAIT we would have to
>> check to see if the next 2 characters are ::, and makes the lexer
>> uber-complicated.  It's a big mess.
> 
> I think this is a point we should take seriously. I see the following 
> solutions:
> 1. Wait with the introduction until either the parser allows such an 
> addition without BC break or wait for the appropriate PHP release. (Is 
> 5.3 the time to introduce this BC break? I don't know the current PHP 
> definitions about major/minor releases)
> 2. Consider this issue carefully when deciding on a syntax. Maybe favour 
> a syntax with fewer new keywords. Reusing keywords like "include", "as" 
> or "not" come to mind.

If the namespace patch is in PHP 5.3 (it is in the snapshots) then we 
are already introducing the new keyword `namespace` that will break BC. 
I think we can take this as reason enough to go ahead and add the 
`trait` keyword. And since we have the following complementary keywords:

  - `class` and `extends`
  - `interface` and `implements`
  - `namespace` and `use`
  - etc.

we should go ahead and introduce the complimentary keyword for `trait`, 
and it doesn't make much sense to reuse one of the other keywords. There 
are already some suggestions on Stefan's RFC, but none of them seem to 
fit as well to me. I think we should throw `import` back onto namespaces 
and use `use` with traits. The `use` or `uses` keyword is consistent 
with other implementations of traits. And if nobody likes that idea, 
what about `inline`, `inject`, `insert`, `add`, or even `+`.

I also have an idea for aliasing that I don't think anyone has thought 
of yet: reusing the `clone` keyword like so:

<?php
class Foo {
   use Bar {
     not foo1;
     clone foo1 as barFoo1;
   }
}

Cloning I think gives us the correct idea of what is actually happening: 
the entire body of method foo1 is copied to a new method called barFoo1.

Also, using `not` for exclusion also gets my vote (although I doubt my 
vote actually matters).

-- 
"Joshua Thompson" <spam.goes.in.here@gmail.com>
<http://www.schmalls.com>