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Date: Wed, 02 Oct 2024 10:06:20 +0200
To: =?UTF-8?Q?Alexandru_P=C4=83tr=C4=83nescu?= <drealecs@gmail.com>,
 "Juliette Reinders Folmer" <php-internals_nospam@adviesenzo.nl>
Cc: "PHP internals" <internals@lists.php.net>,
 "Ayesh Karunaratne" <ayesh@php.watch>
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 <CAAwdEzC8sGt2+PcJfWTfLDooPTsqBk7YAdK-zXs7QMgDALX+LA@mail.gmail.com>
References: <66FC7B9F.5070906@adviesenzo.nl>
 <CAAwdEzC8sGt2+PcJfWTfLDooPTsqBk7YAdK-zXs7QMgDALX+LA@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Add get_declared_enums() function
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From: rob@bottled.codes ("Rob Landers")

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On Wed, Oct 2, 2024, at 09:20, Alexandru P=C4=83tr=C4=83nescu wrote:
>=20
> On Wed, Oct 2, 2024 at 1:48=E2=80=AFAM Juliette Reinders Folmer <php-i=
nternals_nospam@adviesenzo.nl> wrote:
>> L.S.,
>>=20
>> After the earlier discussion [1] regarding this topic in August, it i=
s our pleasure to present the RFC to add a `get_declared_enums()` functi=
on to PHP for discussion.
>>=20
>> https://wiki.php.net/rfc/get_declared_enums
>>=20
>> We look forward to your feedback and hope for a constructive discussi=
on.
>=20
> 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.
>=20
> I noticed how you analyzed things internally, that everything is a cla=
ss 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 t=
hat you can use in different ways in (generated) code.
>=20
> 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 retur=
n enums.
>=20
> 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());
> }
> ```
>=20
> --=20
> Alex
>=20

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 enu=
m 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 th=
e same. For example, you cannot implement arbitrary interfaces (ie, Stri=
ngable), you cannot extend another class, you cannot instantiate them wi=
th =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 b=
e worth implementing a get_declared_objects() that behaves like get_decl=
ared_classes() currently does.=20

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Wed, Oct 2, =
2024, at 09:20, Alexandru P=C4=83tr=C4=83nescu wrote:<br></div><blockquo=
te type=3D"cite" id=3D"qt" style=3D""><div dir=3D"ltr"><div dir=3D"ltr">=
<br></div><div class=3D"qt-gmail_quote"><div dir=3D"ltr" class=3D"qt-gma=
il_attr">On Wed, Oct 2, 2024 at 1:48=E2=80=AFAM Juliette Reinders Folmer=
 &lt;<a href=3D"mailto:php-internals_nospam@adviesenzo.nl">php-internals=
_nospam@adviesenzo.nl</a>&gt; wrote:<br></div><blockquote class=3D"qt-gm=
ail_quote" style=3D"margin-top:0px;margin-right:0px;margin-bottom:0px;ma=
rgin-left:0.8ex;border-left-width:1px;border-left-style:solid;border-lef=
t-color:rgb(204, 204, 204);padding-left:1ex;"><div bgcolor=3D"#FFFFFF"><=
span class=3D"size" style=3D""><span class=3D"font" style=3D"font-family=
:Verdana;">L.S.,<br> <br> After the earlier discussion [1] regarding thi=
s topic in August,=0A        it is our pleasure to present the RFC to ad=
d a=0A        `get_declared_enums()` function to PHP for discussion.<br>=
 <br> <a href=3D"https://wiki.php.net/rfc/get_declared_enums" target=3D"=
_blank" class=3D"">https://wiki.php.net/rfc/get_declared_enums</a><br> <=
br> We look forward to your feedback and hope for a constructive=0A     =
   discussion.<br></span></span></div></blockquote><div><br></div><div>I=
'm all for `get_declared_enums()`.<br></div><div>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.<br></div><div><br></div><di=
v>I noticed how&nbsp;you 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><div>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 are just a specific type of class, final ones.<br></div><=
div>I would find it surprising if `get_declared_classes()` would not ret=
urn enums.<br></div><div><br></div><div>Avoiding a BC break would be nic=
e also if there is no reason for it.<br></div><div>One would be able to =
get only the enums by using something like:<br></div><div><div>```php<br=
></div><div>function get_declared_enums_only() {<br></div><div>&nbsp; &n=
bsp; return array_diff(get_declared_classes(), get_declared_enums());<br=
></div><div>}<br></div><div>```<br></div></div><div><br></div><div>--&nb=
sp;<br></div><div>Alex<br></div><div><br></div></div></div></blockquote>=
<div><br></div><div>Interesting observation&nbsp;Alexandru,<br></div><di=
v><br></div><div>I find it weird that class_exists("MyEnum") would retur=
n true, but there is only one symbol table=E2=80=94you can=E2=80=99t nam=
e 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 int=
erfaces (ie, Stringable), you cannot extend another class, you cannot in=
stantiate them with =E2=80=9Cnew=E2=80=9D, you cannot have state, you ca=
nnot clone them, magic methods are forbidden, etc.<br></div><div><br></d=
iv><div>You cannot build a =E2=80=9Cclass=E2=80=9D with these rules in P=
HP, 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.&nbsp;<br></div><div><br></div><di=
v id=3D"sig121229152">=E2=80=94 Rob<br></div></body></html>
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