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Date: Wed, 29 May 2024 23:43:40 +0300
Message-ID: <CAPyeZ4P9uNfi1pr9iTcanvY0gwujJXsnWKJviqR+S+i2j3N+gw@mail.gmail.com>
Subject: Re: [PHP-DEV] [Discussion] Why can't I do "{$a::class}"?
To: Peter Stalman <sarkedev@gmail.com>
Cc: internals@lists.php.net
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From: udaltsov.valentin@gmail.com (Valentin Udaltsov)

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On Sun, May 19, 2024 at 10:30=E2=80=AFAM Peter Stalman <sarkedev@gmail.com>=
 wrote:

> Hi Internals,
>
> Obviously we can't use constants or functions directly in strings using
> variable parsing, I assume because it lacks the easily detectable $.
>
> However, we _can_ use methods because the object variable has the $, whic=
h
> I assume is the reason methods work and functions don't.
>
> I feel like it's something that _could_ have been added when dynamic
> access of static members support was added in 5.3.0, but maybe it was
> overlooked or decided against?  Consider:
>
> ```
> <?php
>
> $a =3D new A();
>
> echo " {A::$static_property} \n"; // doesn't work (unless $static_propert=
y
> is a variable)
> echo " {$a::$static_property} \n"; // works
>
> echo " {A::static_method()} \n"; // doesn't work (just text)
> echo " {$a::static_method()} \n"; // works
>
> echo " {A::constant} \n"; // doesn't work
> echo " {$a::constant} \n"; // doesn't work either, but why?
>
> ?>
> ```
>
>
> Also, as a side note, why does this hack below work?  It seems like
> something that would use `eval()`, but doesn't.  Take a look:
>
> https://3v4l.org/aPCSD
>
> I found it at the bottom of the manual entry for Strings[1].  Not
> something I would use, but it's interesting to see.
>
> Thanks,
> Peter
>
> [1]: https://www.php.net/manual/en/language.types.string.php#91628
>

Hi, Peter!

> Also, as a side note, why does this hack below work?

It's not a hack. Variables, including callable ones with any arguments are
allowed to be interpolated. See another example: https://3v4l.org/BJUvL
--
Regards,
Valentin Udaltsov

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<div dir=3D"ltr"><div dir=3D"ltr">On Sun, May 19, 2024 at 10:30=E2=80=AFAM =
Peter Stalman &lt;<a href=3D"mailto:sarkedev@gmail.com">sarkedev@gmail.com<=
/a>&gt; wrote:<br></div><div class=3D"gmail_quote"><blockquote class=3D"gma=
il_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,2=
04,204);padding-left:1ex"><div dir=3D"ltr">Hi Internals,<div><br></div><div=
>Obviously=C2=A0we can&#39;t use constants or functions directly in strings=
 using variable parsing, I assume because it lacks the easily detectable $.=
</div><div><br></div><div>However, we _can_ use methods because the object =
variable has the $, which I assume is the reason methods work and functions=
 don&#39;t.</div><div><br></div><div>I feel like it&#39;s something that _c=
ould_ have been added when dynamic access of static members support was add=
ed in 5.3.0, but maybe it was overlooked or decided against?=C2=A0 Consider=
:</div><div><br></div><div>```</div><div>&lt;?php</div><div><br></div><div>=
$a =3D new A();<br><br>echo &quot; {A::$static_property} \n&quot;; // doesn=
&#39;t work (unless $static_property is a variable)<br>echo &quot; {$a::$st=
atic_property} \n&quot;; // works<br><br>echo &quot; {A::static_method()} \=
n&quot;; // doesn&#39;t work (just text)<br>echo &quot; {$a::static_method(=
)} \n&quot;; // works<br><br>echo &quot; {A::constant} \n&quot;; // doesn&#=
39;t work<br>echo &quot; {$a::constant} \n&quot;; // doesn&#39;t work eithe=
r, but why?<br></div><div><br></div><div>?&gt;</div><div>```</div><div><br>=
</div><div><br></div><div>Also, as a side note, why does this hack below wo=
rk?=C2=A0 It seems like something that would use `eval()`, but doesn&#39;t.=
=C2=A0 Take a look:</div><div><br></div><div><a href=3D"https://3v4l.org/aP=
CSD" target=3D"_blank">https://3v4l.org/aPCSD</a><br></div><div><br></div><=
div>I found it at the bottom of the manual entry for Strings[1].=C2=A0 Not =
something I would use, but it&#39;s interesting to see.</div><div><br></div=
><div>Thanks,</div><div>Peter</div><div><br></div><div>[1]:=C2=A0<a href=3D=
"https://www.php.net/manual/en/language.types.string.php#91628" target=3D"_=
blank">https://www.php.net/manual/en/language.types.string.php#91628</a></d=
iv></div>
</blockquote></div><br clear=3D"all"><div><div>Hi, Peter!<span class=3D"gma=
il-im" style=3D"color:rgb(80,0,80)"><br><br>&gt; Also, as a side note, why =
does this hack below work?<br><br></span>It&#39;s not a hack. Variables, in=
cluding callable ones with=C2=A0any arguments are allowed to be interpolate=
d. See another example:=C2=A0<a href=3D"https://3v4l.org/BJUvL" target=3D"_=
blank">https://3v4l.org/BJUvL</a><font color=3D"#888888"><br></font></div><=
font color=3D"#888888"><span class=3D"gmail_signature_prefix">--</span><br>=
<div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Regards,<br>Val=
entin Udaltsov</div></div></font></div></div>

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