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Date: Thu, 18 Jul 2024 19:08:03 +0200
Message-ID: <CABY-Mhzttz-ikTKy4xhJNhH1J3CxK1TTCtvfmNv5VVA77yfk1g@mail.gmail.com>
Subject: Re: [PHP-DEV] Optional constructor body
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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From: olivernybroe@gmail.com (Oliver Nybroe)

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On Thu, 18 Jul 2024 at 15:48, Larry Garfield <larry@garfieldtech.com> wrote:

>
> Please don't top-post.
>
> Since the last time this came up, PSR-12 has been replaced with PER-CS,
> which as of 2.0 now says:
>
> > If a function or method contains no statements or comments (such as an
> empty no-op implementation or when using constructor property promotion),
> then the body SHOULD be abbreviated as {} and placed on the same line as
> the previous symbol, separated by a space.
>
> cf: https://www.php-fig.org/per/coding-style/#44-methods-and-functions
>
> (I... suppose technically it doesn't mention classes, but I've been doing
> it for empty classes too.)
>
> So the "coding style" part of the previous issue has been resolved.
> Whether that changes anyone's mind about whether this should be done or not
> is up to them to decide.
>
> Personally, I'd probably vote for it if it came up, but I agree it's a
> pretty minor improvement and unlikely to pass.  It would probably only be
> worth doing if there were other common-pattern-optimizations around the
> constructor that came with it.  Things like auto-forwarding to the parent,
> or a more compact syntax than a full constructor method, or other things
> that make writing a "pure data" product type easier rather than just s/{}/;/
>
> I don't know what those could look like.  As a data point, in Kotlin
> (which is what my day job is now), constructor properties are always
> promoted, essentially.
>
> class Foo(val a: String, val b: String) { // This is the equivalent of
> PHP's promoted properties.
>
>   val c: Int = 5 // A non-constructor-initialized property. These can have
> hooks, constructor ones I think cannot.
>
>   init {
>     // This is the non-promoted part of a constructor body, and runs after
> the properties are assigned.
>   }
> }
>
> In case of inheritance, there's dedicated required syntax for forwarding
> to the parent:
>
>
> class Foo(val a: String, val b: String) : Bar(b) { // equivalent to
> parent::__construct($b)
>
> }
>
> You can also make the constructor private (etc.) with more explicitness:
>
> class Foo private constructor(val a: String, val b: String) {}
>
> Of note, if there's no constructor then the parens are omitted, and if
> there's no body then the {} body is omitted.  That means a great many
> "value objects"/DTOs, etc just look like this:
>
> class Foo(
>   val a: String,
>   val b: String,
> )
>
> Which would be equivalent to PHP's
>
> class Foo {
>   public function __construct(
>     public readonly string $a,
>     public readonly string $b.
>   ) {}
> }
>
> cf: https://kotlinlang.org/docs/classes.html
>
> To be clear, I'm not suggesting PHP just copy Kotlin directly.  I'm saying
> that if we want to improve the constructor syntax for common cases, which I
> am open to, we should be looking to do something more substantial and
> ergonomic than just replacing {} with ;, and we could probably get some
> good inspiration from other languages in our family.  (Java, Kotlin, C#,
> Swift, etc.)
>
> --Larry Garfield
>


Sorry about the top posting and thank you for your feedback. I'll take that
into account.
I have used Kotlin myself for many years and love how concise the syntax is
there. I'll take a look at other languages and see if I can come up with a
more concise syntax that still feels like PHP.

Else I might try out creating this small RFC first as a good introduction
to the flow, even though it is unlikely to pass.


Best regards
Oliver Nybroe (he/him)

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Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr"><div><div dir=3D"ltr" class=3D"gmail_sign=
ature"><div dir=3D"ltr">On Thu, 18 Jul 2024 at 15:48, Larry Garfield &lt;<a=
 href=3D"mailto:larry@garfieldtech.com">larry@garfieldtech.com</a>&gt; wrot=
e:</div></div></div></div><div class=3D"gmail_quote"><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">
<br>
Please don&#39;t top-post.<br>
<br>
Since the last time this came up, PSR-12 has been replaced with PER-CS, whi=
ch as of 2.0 now says: <br>
<br>
&gt; If a function or method contains no statements or comments (such as an=
 empty no-op implementation or when using constructor property promotion), =
then the body SHOULD be abbreviated as {} and placed on the same line as th=
e previous symbol, separated by a space.<br>
<br>
cf: <a href=3D"https://www.php-fig.org/per/coding-style/#44-methods-and-fun=
ctions" rel=3D"noreferrer" target=3D"_blank">https://www.php-fig.org/per/co=
ding-style/#44-methods-and-functions</a><br>
<br>
(I... suppose technically it doesn&#39;t mention classes, but I&#39;ve been=
 doing it for empty classes too.)<br>
<br>
So the &quot;coding style&quot; part of the previous issue has been resolve=
d.=C2=A0 Whether that changes anyone&#39;s mind about whether this should b=
e done or not is up to them to decide.<br>
<br>
Personally, I&#39;d probably vote for it if it came up, but I agree it&#39;=
s a pretty minor improvement and unlikely to pass.=C2=A0 It would probably =
only be worth doing if there were other common-pattern-optimizations around=
 the constructor that came with it.=C2=A0 Things like auto-forwarding to th=
e parent, or a more compact syntax than a full constructor method, or other=
 things that make writing a &quot;pure data&quot; product type easier rathe=
r than just s/{}/;/<br>
<br>
I don&#39;t know what those could look like.=C2=A0 As a data point, in Kotl=
in (which is what my day job is now), constructor properties are always pro=
moted, essentially.=C2=A0 <br>
<br>
class Foo(val a: String, val b: String) { // This is the equivalent of PHP&=
#39;s promoted properties.<br>
<br>
=C2=A0 val c: Int =3D 5 // A non-constructor-initialized property. These ca=
n have hooks, constructor ones I think cannot.<br>
<br>
=C2=A0 init {<br>
=C2=A0 =C2=A0 // This is the non-promoted part of a constructor body, and r=
uns after the properties are assigned.<br>
=C2=A0 }<br>
}<br>
<br>
In case of inheritance, there&#39;s dedicated required syntax for forwardin=
g to the parent:<br>
<br>
<br>
class Foo(val a: String, val b: String) : Bar(b) { // equivalent to parent:=
:__construct($b)<br>
<br>
}<br>
<br>
You can also make the constructor private (etc.) with more explicitness:<br=
>
<br>
class Foo private constructor(val a: String, val b: String) {}<br>
<br>
Of note, if there&#39;s no constructor then the parens are omitted, and if =
there&#39;s no body then the {} body is omitted.=C2=A0 That means a great m=
any &quot;value objects&quot;/DTOs, etc just look like this:<br>
<br>
class Foo(<br>
=C2=A0 val a: String,<br>
=C2=A0 val b: String,<br>
)<br>
<br>
Which would be equivalent to PHP&#39;s<br>
<br>
class Foo {<br>
=C2=A0 public function __construct(<br>
=C2=A0 =C2=A0 public readonly string $a,<br>
=C2=A0 =C2=A0 public readonly string $b.<br>
=C2=A0 ) {}<br>
}<br>
<br>
cf: <a href=3D"https://kotlinlang.org/docs/classes.html" rel=3D"noreferrer"=
 target=3D"_blank">https://kotlinlang.org/docs/classes.html</a><br>
<br>
To be clear, I&#39;m not suggesting PHP just copy Kotlin directly.=C2=A0 I&=
#39;m saying that if we want to improve the constructor syntax for common c=
ases, which I am open to, we should be looking to do something more substan=
tial and ergonomic than just replacing {} with ;, and we could probably get=
 some good inspiration from other languages in our family.=C2=A0 (Java, Kot=
lin, C#, Swift, etc.)<br>
<br>
--Larry Garfield<br></blockquote><div><br></div><div><br></div><div>Sorry a=
bout the top posting and thank you for your feedback. I&#39;ll take that in=
to account.=C2=A0<br>I have used Kotlin myself for many years and love how =
concise the syntax is there. I&#39;ll take a look at other languages and se=
e if I can come up with a more concise syntax that still feels like PHP.=C2=
=A0<br><br></div><div>Else I might try out creating this small RFC first as=
 a good introduction to the flow, even though it is unlikely to pass.</div>=
<div><br></div><div><br></div>Best regards<div>Oliver Nybroe (he/him)=C2=A0=
</div></div></div>

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