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Subject: Re: [PHP-DEV] bikeshed: Typed Aliases
In-Reply-To: <2bb2b656-aace-462d-b8e3-69d23593c6fd@app.fastmail.com>
Date: Sat, 7 Sep 2024 10:49:47 -0400
Cc: Davey Shafik <davey@php.net>,
 PHP internals <internals@lists.php.net>
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Message-ID: <E70B532F-4080-475E-8C06-BB7D645FBD0D@newclarity.net>
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To: Rob Landers <rob@bottled.codes>,
 Larry Garfield <larry@garfieldtech.com>
From: mike@newclarity.net (Mike Schinkel)

> On Sep 7, 2024, at 9:28 AM, Rob Landers <rob@bottled.codes> wrote:
> Keep in mind there is already single-class aliasing with well-known =
behavior for both local and project-wide aliases. Local aliases are done =
through 'use' statements, and project-wide aliases can be created by =
using the `class_alias()` function.

Good point.=20

While I'd prefer to be able to use a typedef/typealias syntax, I =
certainly would not bikeshed over it.

> On Sep 7, 2024, at 9:21 AM, Larry Garfield <larry@garfieldtech.com> =
wrote:
>> There is definite utility for this, to create a local alias in a=20
>> namespace that can be used throughout the namespace rather than =
having=20
>> to refer to the external namespace in many different places.
>=20
> Because it quickly can produce nonsensical syntax.
>=20
> class A {}
> class B {}
>=20
> typealias AB: A|B;
>=20
> // This is logically nonsensical.
> class C extends AB {}

Gotcha.  That issue had not occurred to me as my use of type aliases is =
in other languages that do not have union types. So I was more concerned =
with this:

namespace A\Really\Long\Namespace {
   class A {}
}
namespace My\Current\Namespace {
   typedef A: \A\Really\Long\Namespace\A {}

   class B extends A {}
}

However, as Rob pointed out there are already ways to accomplish this =
that I was not thinking of, so my concern for extends and implements is =
effectively moot.

> On Sep 7, 2024, at 9:28 AM, Larry Garfield <larry@garfieldtech.com> =
wrote:
> Methods on typedefs was the sort of "other stuff classes do" that I =
was trying to avoid getting into right now. :-)  Mainly because I can =
totally see how it's tempting, but also have no idea what it would mean =
from a type-theoretic perspective.  It would only make sense if we're =
talking type DEFs, not type ALIASes.

That latter sentence is spot-on.

-Mike=