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Date: Thu, 22 Oct 2020 20:40:04 +0200
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To: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Is there any interest for object constructor
 shorthand*just for stdClass*
From: divinity76@gmail.com (Hans Henrik Bergan)

@Rowan Tommins

not saying this is a good idea or anything, but i just want to point
out that there's another way to do it in
7.4
$object =3D new class($foo, $foo * 2, $nextBaz) {
     public int $foo;
     public int $bar;
     public int $baz;
     public function __construct($foo, $bar, $baz) {
        for($i=3D0;$i<func_num_args();++$i){
            $name =3D ((new
ReflectionParameter([$this,__FUNCTION__],$i))->getName());
            $this->$name =3D $$name;
        }
     }
};

haha finally found a use-case for variable-variables

On Thu, 22 Oct 2020 at 14:40, Bj=C3=B6rn Larsson <bjorn.x.larsson@telia.com=
> wrote:
>
> Den 2020-10-21 kl. 22:45, skrev Rowan Tommins:
>
> > On 21/10/2020 10:47, Pierre wrote:
> >> I'd recommend that if your data is arbitrary, you can use arrays, if y=
ou
> >> it's not, you probably always should write typed value objects
> >
> >
> > This is pretty much what I was going to say. If you have truly dynamic
> > keys, then having the full set of array functions available - e.g.
> > array_map, array_filter, all the variations of sort - is almost
> > definitely a win. If you know the property names in advance, then
> > defining them on a class is going to help you catch a lot of mistakes.
> >
> We considered arrays once when migrating our PHP 5 codebase to PHP 7, but
> the cost benefit analyse didn't show any worth while business aspects. Th=
e
> only thing we needed to do was to add one line with new stdClass for the
> PHP 7 migration to succeed.
> >
> > On 21/10/2020 10:38, Bj=C3=B6rn Larsson wrote:
> >> One typical usecase we have is populating an object with the result
> >> from a DB query or using an object to write to a DB.
> >
> >
> > This is certainly common, and even has a built-in mode in PDO.
> > However, I suspect that if we didn't have stdClass, we would no longer
> > see the need to add it just for these use cases, because they could
> > use an anonymous class instead.
>
>
> True, we looked into anonymous classes as another option but it didn't
> improve readability, rather the opposite.
>
> >
> > Which brings me back to the feature request: what if rather than
> > stdClass, we look for a better syntax for creating and populating
> > anonymous class instances? Then you could start with a literal and add
> > real object behaviour to it - add methods, implement an interface,
> > constrain the type of properties, etc.
>
> That's a very good point! We have code today that uses stdClass, so it
> would probably only come into play for new code since the existing
> code runs perfectly fine :-)
> >
> > I think there are two problems we might want to solve there:
> >
> > 1. The only way to initialise the object with variables from the outer
> > scope is to pass them to a constructor, which is a bit messy (although
> > constructor property promotion improves things a bit, see example below=
).
> > 2. There's no way to create a truly dynamic class, i.e. one with some
> > or all properties determined at run-time, without extensive string
> > manipulation and eval(). (Although you can simply write "$object =3D ne=
w
> > class{}; $object->foo=3D42;" to add a public, untyped property).
> >
> > The proposed syntax would help with (1), but not really with (2),
> > since you need to know at least the _number_ of properties in order to
> > write out the literal.
> >
> >
> > Examples, and some probably bad ideas, in the hope they inspire
> > someone to better ideas:
> >
> > // 7.4
> > $object =3D new class($foo, $foo * 2, $nextBaz) {
> >     public int $foo;
> >     public int $bar;
> >     public int $baz;
> >     public function __construct($foo, $bar, $baz) {
> >           $this->foo=3D$foo;
> >           $this->bar=3D$bar;
> >           $this->baz=3D$baz;
> >     }
> > };
> >
> > // 8.0
> > $object =3D new class($foo, $foo * 2, $nextBaz) {
> >     public function __construct(public int $foo, public int $bar,
> > public int $baz) {}
> > };
> >
> > // Promote properties into named parameters, implicitly defining a
> > constructor and passing them to it?
> > $object =3D new class(public int foo: $foo, public int bar: $foo * 2,
> > public int baz: $nextBaz) {};
> >
> > // Extend this to accept an array spread? Means all properties have to
> > have the same visibility and type, or default to "public mixed"...
> > $data =3D ['foo' =3D> 42, 'bar' =3D> 84, 'baz' =3D> 69]; // dynamic dat=
a, e.g.
> > a DB result set row
> > $object =3D new class(public int ...$data) {};
> >
> Interesting alternatives!
> >
> > Regards,
> >
> r//Bj=C3=B6rn L
>
> --
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