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Date: Fri, 7 Jun 2024 21:02:39 +0200
Message-ID: <CAB-BujZQYnni3u1-OroN5CEkx7LXXKbkfUmRU42kp00h7s0qyw@mail.gmail.com>
Subject: Re: [PHP-DEV] RFC proposal : "new" keyword shorthand
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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From: andreas@dqxtech.net (Andreas Hennings)

On Fri, 7 Jun 2024 at 20:31, Larry Garfield <larry@garfieldtech.com> wrote:
>
> 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 t=
o 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 call=
s a constructor (kinda sorta like C# extension methods)? Something kinda li=
ke:
> >>
> >> class MyClass implements Invocable {
> >>   public function __construct($i) {}
> >> }
> >>
> >> MyClass($i);
> >>
> >> Where the Invocable interface defines a function of the same class nam=
e in the namespace that is an alias for a new objects and forwards args to =
the constructor. This could be quite handy for value objects.
> >>
> >> I=E2=80=99m not necessarily a fan of magic or symbols, but just tossin=
g 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). But
> > 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 PHP
> > 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 default
> > behavior of this kind of interface to support immutability, comparison,
> > 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 that=
 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 fat=
al.
>
> If we had function autoloading, that would work, assuming a reasonable ge=
neric autoloader for that case could be written.  Who was it that's been ta=
lking about that for a while? :-)
>
> Or if we had some marker to indicate "this function call is a wrapper for=
 a class so autoload it like a class", that could then trigger the class au=
toloader.  But... that's basically what the original ~ proposal is, in the =
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