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Date: Fri, 06 Sep 2024 20:41:23 +0200
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Subject: [PHP-DEV] bikeshed: Typed Aliases
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From: rob@bottled.codes ("Rob Landers")

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Hello Internals,

I'm going to try something new. I've been working on another RFC called =
"Typed Aliases" (https://wiki.php.net/rfc/typed-aliases). It is very muc=
h a draft and in-flux, and I've already worked out the technical mechani=
cs of it ... however, I am very unhappy with the syntax, and while I hav=
e a few ideas about that; I assume this list will be much better at it t=
han me. So, please bring your brushes and paint; I brought a bikeshed.

If you haven't read it already, here's the TL;DR:

- This RFC expands the "use ... as ..." syntax to allow any type express=
ion on the left side. These aliases are PER FILE and expire once the fil=
e is compiled.

- This RFC also adds the ability for an alias to survive a file (current=
ly using the "as alias" syntax that I don't like) which actually just cr=
eates a special kind of class. When this special class is encountered du=
ring type-checking, the alias is expanded and checked. It also allows th=
is via a "type_alias()" function instead of the "use ... as alias ..." s=
yntax.

How it works:

use string as alias MyString

gets virtually compiled into a special class that would look something l=
ike this to ReflectionClass (as it is currently):

class MyString extends PrimitiveAlias {=20
  const PrimitiveType aliasOf =3D PrimitiveType::string;
}

- Reflection is a bit weird here, and I'm not exactly happy with it; but=
 I'm curious what the list thinks. I'm open to virtually anything that m=
akes sense here; including not allowing ReflectionClass on the type alia=
ses at all.

- Since these are "technically" classes, I went with just "use"-ing them=
 like normal classes. Originally, I had something different: "use alias =
..." (like "use function ...") to make it more clear. I will probably go=
 back to this, but I'm curious what others think.

I'm going to take a step back and listen/answer questions. But please, g=
rab a brush and paint.

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>Hello Internals=
,<br></div><div><br></div><div>I'm going to try something new. I've been=
 working on another RFC called "Typed Aliases" (<a href=3D"https://wiki.=
php.net/rfc/typed-aliases">https://wiki.php.net/rfc/typed-aliases</a>). =
It is very much a draft and in-flux, and I've already worked out the tec=
hnical mechanics of it ... however, I am very unhappy with the syntax, a=
nd while I have a few ideas about that; I assume this list will be much =
better at it than me. So, please bring your brushes and paint; I brought=
 a bikeshed.<br></div><div><br></div><div>If you haven't read it already=
, here's the TL;DR:<br></div><div><br></div><div>- This RFC expands the =
"use ... as ..." syntax to allow any type expression on the left side. T=
hese aliases are PER FILE and expire once the file is compiled.<br></div=
><div><br></div><div>- This RFC also adds the ability for an alias to su=
rvive a file (currently using the "as alias" syntax that I don't like) w=
hich actually just creates a special kind of class. When this special cl=
ass is encountered during type-checking, the alias is expanded and check=
ed. It also allows this via a "type_alias()" function instead of the "us=
e ... as alias ..." syntax.<br></div><div><br></div><div>How it works:</=
div><div><br></div><div>use string as alias MyString<br></div><div><br><=
/div><div> gets virtually compiled into a special class that would look =
something like this to ReflectionClass (as it is currently):<br></div><d=
iv><br></div><div>class MyString extends PrimitiveAlias { <br></div><div=
>&nbsp; const PrimitiveType aliasOf =3D PrimitiveType::string;<br></div>=
<div>}</div><div><br></div><div>- Reflection is a bit weird here, and I'=
m not exactly happy with it; but I'm curious what the list thinks. I'm o=
pen to virtually anything that makes sense here; including not allowing =
ReflectionClass on the type aliases at all.<br></div><div><br></div><div=
>- Since these are "technically" classes, I went with just "use"-ing the=
m like normal classes. Originally, I had something different: "use alias=
 ..." (like "use function ...") to make it more clear. I will probably g=
o back to this, but I'm curious what others think.<br></div><div><br></d=
iv><div>I'm going to take a step back and listen/answer questions. But p=
lease, grab a brush and paint.</div><div><br></div><div id=3D"sig1212291=
52">=E2=80=94 Rob</div></body></html>
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