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Date: Sat, 17 Aug 2024 13:12:40 +0100
To: internals@lists.php.net
Subject: Re: [PHP-DEV] String enums & __toString()
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")



On 17 August 2024 01:47:20 BST, John Coggeshall <john@coggeshall=2Eorg> wr=
ote:
> What's the point of a Stringable interface if we can't actually implemen=
t __toString() for it?=20

Just to show the range of viewpoints on this, I'd like to mention my opini=
on that Stringable is a horrible feature, with an implementation that's com=
pletely inconsistent with the rest of the language, and no clear semantic p=
urpose=2E If your contract is "the input must be usable as a string", then =
the obvious type to require is "string"=2E

I'm not saying my opinion is objectively right, or even held by a majority=
, I just wanted to provide a counterbalance of sorts=2E


>function fooThatWantsString(string|Stringable|UnitEnum $bar)
>{
>if(($bar instanceof UnitEnum) && !is_string($bar->value)) {
>throw InvalidArgumentException('This is exactly the sort of thing we are =
trying to get rid of with type hinting');
>} else {
>$bar =3D $bar->value;
>}
>
>$bar =3D (string)$bar;
>}

I would have thought the more common use case would be the opposite: you w=
ant the function to be limited to a particular enum, but allow strings for =
backward compatibility, and have this:=20

function fooThatTakesAnOption(FooOptionEnum|string $opt) {
      if ( is_string($opt) ) {
           $opt =3D FooOptionEnum::from($opt);
      }
      =2E=2E=2E
}

You might later want to use $opt->value, or $opt->getApiRepresentation(), =
or whatever else; but at that point you know you have an object of a partic=
ular type=2E


Regards,
Rowan Tommins
[IMSoP]