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Date: Fri, 14 Mar 2025 18:37:27 +0100
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Subject: Re: [PHP-DEV] RFC: short and inner classes
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From: rob@bottled.codes ("Rob Landers")

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On Fri, Mar 14, 2025, at 17:09, Ilija Tovilo wrote:
> Hi Bob
>=20
> On Thu, Mar 13, 2025 at 11:36=E2=80=AFPM Bob Weinand <bobwei9@hotmail.=
com> wrote:
> >
> > On 6.3.2025 23:20:37, Ilija Tovilo wrote:
> >
> > > I would also like to echo what has been said about the :: operator,
> > > which feels out of place. I understand that \ comes with additional
> > > autoloading challenges, namely requiring a fallback autoloading
> > > strategy that currently does not conform to PSR-4.
> >
> > Could you please elaborate on why the :: operator feels out of place?
> >
> > \ is a namespace separator.
> >
> > :: is a class scoping separator.
> >
> >
> > You, yourself did decide to use nested :: for property hook scoping,=
 like parent::$x::set() - a property scoped within a class, having metho=
ds.
> > The same applies here - it's a class scoped within a class, having m=
ethods.
> >
> > Breaking from these patterns seems very surprising to me.
>=20
> :: is an operation performed on the class. E.g. fetch a static
> property, fetch a constant, call a static method, while \ is part of
> the class name. The way I see it, the outer class can simply add an
> additional namespace component to the inner class.
>=20
> class Foo {
>     class Bar {} // Called Foo\Bar
>=20
>     public Bar $bar;
> }
>=20
> This is dead simple, it doesn't change any assumptions about class
> names by embedding new symbols, it doesn't need a new operator, you
> can refer to the class with its short name from inside the outer class
> without `self:>`, which is shorter and more straight forward, `use
> Foo\Bar;` will just work in other classes, etc.
>=20
> One thing this approach breaks is that it doesn't allow for
> polymorphic inner class resolution, i.e. static:>Bar. But given this
> was removed anyway, that point no longer applies. This can also easily
> be replicated by a simple method:
>=20
> class Foo {
>     class Bar {}
>=20
>     public function createBar(): Bar {
>         return new Bar();
>     }
> }
>=20
> Except this is actually type-safe, because the return value of
> createBar() must stay compatible with Foo\Bar.
>=20
> Ilija
>=20

Hi Ilija,

What about a hybrid approach? Maybe something like `\\` that Tim suggest=
ed? But hear me out. Instead of it being between all inner parts, it is =
only between the outermost and inner parts of the class, otherwise just =
use `\`. This also solves a problem where:

- we don't need to change anything with autoloading
- we can differentiate between different types with the same name

So

namespace Foo;

class Outer {
  class Middle {
    class Inner {}
  }
}

namespace Foo\Outer;

class Middle {
}

can be differentiated from each other (Foo\Outer\Middle vs. Foo\Outer\\M=
iddle\Inner).

I also like the idea of just using the name instead of having Foo:>Bar..=
. I think that is possible now that I have all the machinery in place fo=
r visibility. I may have the implementation ready today/tomorrow (as per=
 the currently written RFC). =F0=9F=A4=9E

=E2=80=94 Rob
--6be66dd0d96247f4be3fae63cd776e45
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}=0Ap.MsoNormal,p.MsoNoSpacing{margin:0}</=
style></head><body><div><br></div><div><br></div><div>On Fri, Mar 14, 20=
25, at 17:09, Ilija Tovilo wrote:<br></div><blockquote type=3D"cite" id=3D=
"qt" style=3D""><div>Hi Bob<br></div><div><br></div><div>On Thu, Mar 13,=
 2025 at 11:36=E2=80=AFPM Bob Weinand &lt;<a href=3D"mailto:bobwei9@hotm=
ail.com">bobwei9@hotmail.com</a>&gt; wrote:<br></div><div>&gt;<br></div>=
<div>&gt; On 6.3.2025 23:20:37, Ilija Tovilo wrote:<br></div><div>&gt;<b=
r></div><div>&gt; &gt; I would also like to echo what has been said abou=
t the :: operator,<br></div><div>&gt; &gt; which feels out of place. I u=
nderstand that \ comes with additional<br></div><div>&gt; &gt; autoloadi=
ng challenges, namely requiring a fallback autoloading<br></div><div>&gt=
; &gt; strategy that currently does not conform to PSR-4.<br></div><div>=
&gt;<br></div><div>&gt; Could you please elaborate on why the :: operato=
r feels out of place?<br></div><div>&gt;<br></div><div>&gt; \ is a names=
pace separator.<br></div><div>&gt;<br></div><div>&gt; :: is a class scop=
ing separator.<br></div><div>&gt;<br></div><div>&gt;<br></div><div>&gt; =
You, yourself did decide to use nested :: for property hook scoping, lik=
e parent::$x::set() - a property scoped within a class, having methods.<=
br></div><div>&gt; The same applies here - it's a class scoped within a =
class, having methods.<br></div><div>&gt;<br></div><div>&gt; Breaking fr=
om these patterns seems very surprising to me.<br></div><div><br></div><=
div>:: is an operation performed on the class. E.g. fetch a static<br></=
div><div>property, fetch a constant, call a static method, while \ is pa=
rt of<br></div><div>the class name. The way I see it, the outer class ca=
n simply add an<br></div><div>additional namespace component to the inne=
r class.<br></div><div><br></div><div>class Foo {<br></div><div>&nbsp;&n=
bsp;&nbsp; class Bar {} // Called Foo\Bar<br></div><div><br></div><div>&=
nbsp;&nbsp;&nbsp; public Bar $bar;<br></div><div>}<br></div><div><br></d=
iv><div>This is dead simple, it doesn't change any assumptions about cla=
ss<br></div><div>names by embedding new symbols, it doesn't need a new o=
perator, you<br></div><div>can refer to the class with its short name fr=
om inside the outer class<br></div><div>without `self:&gt;`, which is sh=
orter and more straight forward, `use<br></div><div>Foo\Bar;` will just =
work in other classes, etc.<br></div><div><br></div><div>One thing this =
approach breaks is that it doesn't allow for<br></div><div>polymorphic i=
nner class resolution, i.e. static:&gt;Bar. But given this<br></div><div=
>was removed anyway, that point no longer applies. This can also easily<=
br></div><div>be replicated by a simple method:<br></div><div><br></div>=
<div>class Foo {<br></div><div>&nbsp;&nbsp;&nbsp; class Bar {}<br></div>=
<div><br></div><div>&nbsp;&nbsp;&nbsp; public function createBar(): Bar =
{<br></div><div>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return new Ba=
r();<br></div><div>&nbsp;&nbsp;&nbsp; }<br></div><div>}<br></div><div><b=
r></div><div>Except this is actually type-safe, because the return value=
 of<br></div><div>createBar() must stay compatible with Foo\Bar.<br></di=
v><div><br></div><div>Ilija<br></div><div><br></div></blockquote><div><b=
r></div><div>Hi&nbsp;Ilija,<br></div><div><br></div><div>What about a hy=
brid approach? Maybe something like `\\` that Tim suggested? But hear me=
 out. Instead of it being between all inner parts, it is only between th=
e outermost and inner parts of the class, otherwise just use `\`. This a=
lso solves a problem where:<br></div><div><br></div><div>- we don't need=
 to change anything with autoloading<br></div><div>- we can differentiat=
e between different types with the same name<br></div><div><br></div><di=
v>So<br></div><div><br></div><div>namespace Foo;</div><div><br></div><di=
v>class Outer {<br></div><div>&nbsp; class Middle {<br></div><div>&nbsp;=
 &nbsp; class Inner {}<br></div><div>&nbsp; }<br></div><div>}<br></div><=
div><br></div><div>namespace Foo\Outer;</div><div><br></div><div>class M=
iddle {<br></div><div>}<br></div><div><br></div><div>can be differentiat=
ed from each other (Foo\Outer\Middle vs. Foo\Outer\\Middle\Inner).<br></=
div><div><br></div><div>I also like the idea of just using the name inst=
ead of having Foo:&gt;Bar... I think that is possible now that I have al=
l the machinery in place for visibility. I may have the implementation r=
eady today/tomorrow (as per the currently written RFC). =F0=9F=A4=9E</di=
v><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob<br></div></body>=
</html>
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