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Date: Wed, 1 Jul 2015 21:28:16 -0500
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To: Anatol Belski <anatol.php@belski.net>
Subject: Re: [PHP-DEV] [RFC] UString
From: aaron@icicle.io (Aaron Piotrowski)


> On Jul 1, 2015, at 2:25 PM, Anatol Belski <anatol.php@belski.net> =
wrote:
>=20
>> Expanding on this idea, a separate RFC could propose a magic
> __cast($value)
>> static method that would be called for code like below:
>>=20
>> $obj =3D (ClassName) $scalarOrObject; // Invokes
>> ClassName::__cast($scalarOrObject);
>>=20
>> This would allow UString to implement casting a string to a UString =
and
> allow
>> users to implement such behavior with their own classes.
>>=20
>> However, I would not implement such casting syntax for UString only. =
Being
> able
>> to write $ustring =3D (UString) $string; without the ability to do so =
for
> other classes
>> would be unusual and confusing in my opinion. If an RFC adding such
> behavior
>> was implemented, UString could be updated to support casting.
>>=20
>> Obviously a UString should be able to be cast to a scalar string =
using
> (string)
>> $ustring. If performance is a concern, UString::__toString() should =
cache
> the
>> result so multiple casts to the same object are quick.


> Hi,
>=20
> One way doing this is already there thanks
> https://wiki.php.net/rfc/operator_overloading_gmp . Consider
>=20
> $n =3D gmp_init(42); var_dump($n, (int)$n);
>=20
> However the other way round - could be done on case by case basis, =
IMHO.
> Where it could make sense for class vs scalar, casting class to class =
is a
> quite unpredictable thing.
>=20
> While users could implement it, how is it handled with arbitrary =
objects?
> How would it map properties, would those classes need to implement the =
same
> interface, et cetera? We're not in C at this point, where we would =
just
> force a block of memory to be interpreted as we want.
>=20
> Regards
>=20
> Anatol

Hello,

I was thinking that the __cast() static method would examine the =
parameter given, then use that value to build a new object and return it =
or return null (which would then result in the engine throwing an Error =
saying that $scalarOrValue could not be cast to ClassName). It was just =
a suggestion to see what others thought because someone suggested =
supporting casting syntax such as $ustring =3D (UString) $scalarString. =
I don=E2=80=99t really care for either method though (__cast() or =
enabling casting just for UString), as they don't offer any advantage =
over writing new UString($string) or UString::fromString($string).

Aaron Piotrowski=