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Date: Wed, 2 Oct 2024 15:27:22 +0300
Message-ID: <CAAwdEzB+iHSmogoj=Yu4RVw8rY+B6Og_ORCMCg7LnoKxZ9cP6g@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Add get_declared_enums() function
To: Rob Landers <rob@bottled.codes>
Cc: Juliette Reinders Folmer <php-internals_nospam@adviesenzo.nl>, 
	PHP internals <internals@lists.php.net>, Ayesh Karunaratne <ayesh@php.watch>
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From: drealecs@gmail.com (=?UTF-8?Q?Alexandru_P=C4=83tr=C4=83nescu?=)

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On Wed, Oct 2, 2024 at 11:06=E2=80=AFAM Rob Landers <rob@bottled.codes> wro=
te:

> On Wed, Oct 2, 2024, at 09:20, Alexandru P=C4=83tr=C4=83nescu wrote:
>
>
> On Wed, Oct 2, 2024 at 1:48=E2=80=AFAM Juliette Reinders Folmer <
> php-internals_nospam@adviesenzo.nl> wrote:
>
> L.S.,
>
> After the earlier discussion [1] regarding this topic in August, it is ou=
r
> pleasure to present the RFC to add a `get_declared_enums()` function to P=
HP
> for discussion.
>
> https://wiki.php.net/rfc/get_declared_enums
>
> We look forward to your feedback and hope for a constructive discussion.
>
>
> I'm all for `get_declared_enums()`.
> However, I don't accept that enums are not classes and going with the
> assumption that they are not will bring more problems than it solves.
>
> I noticed how you analyzed things internally, that everything is a class
> internally, including an interface or a trait.
> But this is an API for the userland, and in userland this is not true.
> The 3 structures: classes, interfaces and traits and distinct things that
> you can use in different ways in (generated) code.
>
> I believe that in userland, the common understanding is that enums are
> just a specific type of class, final ones.
> I would find it surprising if `get_declared_classes()` would not return
> enums.
>
> Avoiding a BC break would be nice also if there is no reason for it.
> One would be able to get only the enums by using something like:
> ```php
> function get_declared_enums_only() {
>     return array_diff(get_declared_classes(), get_declared_enums());
> }
> ```
>
> --
> Alex
>
>
> Interesting observation Alexandru,
>
> I find it weird that class_exists("MyEnum") would return true, but there
> is only one symbol table=E2=80=94you can=E2=80=99t name a class and enum =
with the same
> name, so it makes some sense. However, while enums have =E2=80=9Csome=E2=
=80=9D similarities
> with classes in PHP, they are not the same. For example, you cannot
> implement arbitrary interfaces (ie, Stringable), you cannot extend anothe=
r
> class, you cannot instantiate them with =E2=80=9Cnew=E2=80=9D, you cannot=
 have state, you
> cannot clone them, magic methods are forbidden, etc.
>
> You cannot build a =E2=80=9Cclass=E2=80=9D with these rules in PHP, so I =
don=E2=80=99t think enums
> quack sufficiently like classes to be called a class. I would argue that =
it
> is an object, however. I think it would be worth implementing a
> get_declared_objects() that behaves like get_declared_classes() currently
> does.
>
> =E2=80=94 Rob
>

Yes, that's a good point as well.

I think my view comes from when I initially dug (15+ years ago) into what
an enum in Java is, and learned that it is just a syntactic sugar, and a
final class would be generated implementing `Comparable` and extending an
abstract class `Enum`.

And I think in PHP that could be a similar view. And most of the
limitations we have are not impossible to create with a standard class.

I think in time we might get to remove some limitations.
I, personally, don't agree with the `Stringable` related limitation.
And also with the limitation on no state. In Java this is the simple way to
create a singleton: an enum with one case; and we can't have this in PHP.

If we remove the limitations, should we reclassify at that point enums as
classes?

--=20
Alex

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><div class=3D"gmail_quote"><div=
 dir=3D"ltr" class=3D"gmail_attr">On Wed, Oct 2, 2024 at 11:06=E2=80=AFAM R=
ob Landers &lt;rob@bottled.codes&gt; wrote:<br></div><blockquote class=3D"g=
mail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204=
,204,204);padding-left:1ex"><div class=3D"msg4813216649018816483"><u></u><d=
iv><div>On Wed, Oct 2, 2024, at 09:20, Alexandru P=C4=83tr=C4=83nescu wrote=
:<br></div><blockquote type=3D"cite" id=3D"m_4813216649018816483qt"><div di=
r=3D"ltr"><div dir=3D"ltr"><br></div><div><div dir=3D"ltr">On Wed, Oct 2, 2=
024 at 1:48=E2=80=AFAM Juliette Reinders Folmer &lt;<a href=3D"mailto:php-i=
nternals_nospam@adviesenzo.nl" target=3D"_blank">php-internals_nospam@advie=
senzo.nl</a>&gt; wrote:<br></div><blockquote style=3D"margin:0px 0px 0px 0.=
8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor=
=3D"#FFFFFF"><span><span style=3D"font-family:Verdana">L.S.,<br> <br> After=
 the earlier discussion [1] regarding this topic in August,
        it is our pleasure to present the RFC to add a
        `get_declared_enums()` function to PHP for discussion.<br> <br> <a =
href=3D"https://wiki.php.net/rfc/get_declared_enums" target=3D"_blank">http=
s://wiki.php.net/rfc/get_declared_enums</a><br> <br> We look forward to you=
r feedback and hope for a constructive
        discussion.<br></span></span></div></blockquote><div><br></div><div=
>I&#39;m all for `get_declared_enums()`.<br></div><div>However, I don&#39;t=
 accept that enums are not classes and going with the assumption that they =
are not will bring more problems than it solves.<br></div><div><br></div><d=
iv>I noticed how=C2=A0you analyzed things internally, that everything is a =
class internally, including an interface or a trait.<br></div><div>But this=
 is an API for the userland, and in userland this is not true.<br></div><di=
v>The 3 structures: classes, interfaces and traits and distinct things that=
 you can use in different ways in (generated) code.<br></div><div><br></div=
><div>I believe that in userland, the common understanding is that enums ar=
e just a specific type of class, final ones.<br></div><div>I would find it =
surprising if `get_declared_classes()` would not return enums.<br></div><di=
v><br></div><div>Avoiding a BC break would be nice also if there is no reas=
on for it.<br></div><div>One would be able to get only the enums by using s=
omething like:<br></div><div><div>```php<br></div><div>function get_declare=
d_enums_only() {<br></div><div>=C2=A0 =C2=A0 return array_diff(get_declared=
_classes(), get_declared_enums());<br></div><div>}<br></div><div>```<br></d=
iv></div><div><br></div><div>--=C2=A0<br></div><div>Alex<br></div><div><br>=
</div></div></div></blockquote><div><br></div><div>Interesting observation=
=C2=A0Alexandru,<br></div><div><br></div><div>I find it weird that class_ex=
ists(&quot;MyEnum&quot;) would return true, but there is only one symbol ta=
ble=E2=80=94you can=E2=80=99t name a class and enum with the same name, so =
it makes some sense. However, while enums have =E2=80=9Csome=E2=80=9D simil=
arities with classes in PHP, they are not the same. For example, you cannot=
 implement arbitrary interfaces (ie, Stringable), you cannot extend another=
 class, you cannot instantiate them with =E2=80=9Cnew=E2=80=9D, you cannot =
have state, you cannot clone them, magic methods are forbidden, etc.<br></d=
iv><div><br></div><div>You cannot build a =E2=80=9Cclass=E2=80=9D with thes=
e rules in PHP, so I don=E2=80=99t think enums quack sufficiently like clas=
ses to be called a class. I would argue that it is an object, however. I th=
ink it would be worth implementing a get_declared_objects() that behaves li=
ke get_declared_classes() currently does.=C2=A0<br></div><div><br></div><di=
v id=3D"m_4813216649018816483sig121229152">=E2=80=94 Rob<br></div></div></d=
iv></blockquote><div><br></div><div>Yes, that&#39;s a good point as well.</=
div><div><br></div><div>I think my view comes from when I initially dug (15=
+ years ago) into what an enum in Java is, and learned that it is just a sy=
ntactic sugar, and a final class would be generated implementing `Comparabl=
e` and extending an abstract class `Enum`.<br></div><div><br></div><div>And=
 I think in PHP that could be a similar view. And most of the limitations w=
e have are not impossible to create with a standard class.</div><div><br></=
div><div>I think in time we might get to remove some limitations.</div><div=
>I, personally, don&#39;t agree with the `Stringable` related limitation.</=
div><div>And also with the limitation on no state. In Java this is the simp=
le way to create a singleton: an enum with one case; and we can&#39;t have =
this in PHP.</div><div><br></div><div>If we remove the limitations, should =
we reclassify=C2=A0at that point enums as classes?</div><div><br></div><div=
>--=C2=A0</div><div>Alex</div><div>=C2=A0</div></div></div>

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