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Date: Sun, 19 May 2024 12:39:29 +0200
Message-ID: <CAPzBOBNdVtVsRWB3BnHtA2CRmN-qjwHUBDBWnv2tLn_rkm7raA@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: landers.robert@gmail.com (Robert Landers)

On Sun, May 19, 2024 at 10:33=E2=80=AFAM Peter Stalman <sarkedev@gmail.com>=
 wrote:
>
> Hi Internals,
>
> Obviously we can't use constants or functions directly in strings using v=
ariable 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 acce=
ss of static members support was added in 5.3.0, but maybe it was overlooke=
d 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 somet=
hing 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 somethi=
ng I would use, but it's interesting to see.
>
> Thanks,
> Peter
>
> [1]: https://www.php.net/manual/en/language.types.string.php#91628

In general, it would be nice to have some proper inline string
templating, like other languages (js, C#, etc). At least some way to
evaluate an expression and format. I'm thinking like in C#:

$"Price: {price:C2}, Quantity: {quantity}, Discount: {discount:P1},
Total after discount: {(price * quantity * (1 - discount)):N2}"

Price is formatted using currency with 2 decimal places, discount is
formatted using percentage and one decimal, and N is a number format
with 2 decimals.

Robert Landers
Software Engineer
Utrecht NL