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Date: Fri, 7 Jun 2024 21:27:40 +0200
Message-ID: <CAB-BujY1-Juvidr37evv8sP=PAA-w5s39tRpqbeKb-Be+EjifQ@mail.gmail.com>
Subject: Re: [PHP-DEV] RFC proposal : "new" keyword shorthand
To: Rob Landers <rob@bottled.codes>
Cc: Larry Garfield <larry@garfieldtech.com>, php internals <internals@lists.php.net>
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From: andreas@dqxtech.net (Andreas Hennings)

On Fri, 7 Jun 2024 at 21:17, Rob Landers <rob@bottled.codes> wrote:
>
>
>
> On Fri, Jun 7, 2024, at 21:02, Andreas Hennings wrote:
>
> On Fri, 7 Jun 2024 at 20:31, Larry Garfield <larry@garfieldtech.com> wrot=
e:
> >
> > On Fri, Jun 7, 2024, at 5:56 PM, ericmann@php.net wrote:
> >
> > >> Instead of ~ (which reminds me of the pendulum of symbols to written=
 to symbols and back again every 10ish years; =E2=80=9Cor=E2=80=9D vs =E2=
=80=9C||=E2=80=9D), why not make a shorthand way to write a function that c=
alls a constructor (kinda sorta like C# extension methods)? Something kinda=
 like:
> > >>
> > >> class MyClass implements Invocable {
> > >>   public function __construct($i) {}
> > >> }
> > >>
> > >> MyClass($i);
> > >>
> > >> Where the Invocable interface defines a function of the same class n=
ame in the namespace that is an alias for a new objects and forwards args t=
o the constructor. This could be quite handy for value objects.
> > >>
> > >> I=E2=80=99m not necessarily a fan of magic or symbols, but just toss=
ing it out there to spark ideas.
> > >>
> > >> =E2=80=94 Rob
> > > --
> > >
> > > I'm not a fan of using ~ for this shorthand, due to the same issues
> > > that have been brought up elsewhere (i.e. it already has meaning). Bu=
t
> > > the idea of a new interface auto-defining a function of the same name
> > > is attractive. It's something I've done manually to mirror code in PH=
P
> > > from other implementations existing in Scala leveraging case classes.
> > >
> > > https://docs.scala-lang.org/tour/case-classes.html for anyone
> > > unfamiliar with the construct:
> > >
> > > ```
> > > case class Book(isbn: String)
> > >
> > > val frankenstein =3D Book("978-0486282114")
> > > ```
> > >
> > > Doing something like this in PHP is a bit more ... verbose today:
> > >
> > > ```
> > > class Book
> > > {
> > >     public function __construct(public string $isbn) {}
> > > }
> > >
> > > function Book(string $isbn): Book
> > > {
> > >     return new Book($isbn);
> > > }
> > >
> > > $frankenstein =3D Book("978-0486282114")
> > > ```
> > >
> > > That's a lot of boilerplate for the shorthand to not require a `new`
> > > keyword. Which is to say, I both agree in principle with the RFC and
> > > think this would add value (particularly if I could extend the defaul=
t
> > > behavior of this kind of interface to support immutability, compariso=
n,
> > > etc similar to Scala case classes). I'm just not a fan of the current=
 ~
> > > proposal.
> > >
> > > ~Eric
> >
> > The issue with auto-generating a function constructor for a class is th=
at we still don't have function autoloading.  Which means this:
> >
> > // Point.php
> >
> > #[MakeFactoryFunction] (or whatever)
> > class Point {
> >   public function __construct(public int $x, public int $y) {}
> > }
> >
> > // index.php
> >
> > $p =3D Point(4, 5);
> >
> > will look for a function named "Point", not find one defined yet, and f=
atal.
> >
> > If we had function autoloading, that would work, assuming a reasonable =
generic autoloader for that case could be written.  Who was it that's been =
talking about that for a while? :-)
> >
> > Or if we had some marker to indicate "this function call is a wrapper f=
or a class so autoload it like a class", that could then trigger the class =
autoloader.  But... that's basically what the original ~ proposal is, in th=
e end.  Though I agree that ~ is not a great symbol for it.  PHP has, sadly=
, run out of unused symbols.  (I've run into this a couple of times now.)
> >
> > --Larry Garfield
>
>
>
> Hello Benoit.
> others already pointed out problems with the `$obj =3D ~C();` syntax,
> but also with the other option, `$obj =3D C();`.
>
> Personally I would prefer a suffix operator that would look similar to
> a static method call.
> This would make it a lot easier to switch between calling a static
> factory and "new."
>
> Unfortunately, `$obj =3D C::new();` is not an option, because "new" is a
> legal method name, so there could already be existing methods with
> that name.
> Also, `$obj =3D C::__construct();` would be just wrong.
>
> But if we can find anything in that direction, I would much prefer it
> over a prefix operator.
> E.g. `$obj =3D C::+();` is currently not valid syntax, so it would be a
> candidate, even though I don't really like it.
>
> -- Andreas
>
>
> If we wanted a suffix, why not just use an empty ::?
>
> $frankenstein =3D Book::($isbn);
>
> =E2=80=94 Rob

I am not strictly opposed to `$obj =3D C::()`.

One problem I can imagine is `$obj =3D C::{$method}();`, where for some
reason null or empty string '' is passed as $method. Currently, php
will fail if this happens. But with the C::() syntax, it would then
silently create a new instance.

The same would happen if an unlucky find/replace removes the method name.

Not sure if that's a blocker.

-- Andreas