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Date: Mon, 8 Apr 2019 17:24:47 +0700
Cc: Dan Ackroyd <Danack@basereality.com>,
 Guilliam Xavier <guilliam.xavier@gmail.com>,
 PHP internals <internals@lists.php.net>,
 David Rodrigues <david.proweb@gmail.com>
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To: Benjamin Morel <benjamin.morel@gmail.com>
Subject: Re: [PHP-DEV] [RFC] Nullable Casting
From: php-lists@koalephant.com (Stephen Reay)


> On 8 Apr 2019, at 16:35, Benjamin Morel <benjamin.morel@gmail.com> =
wrote:
>=20
>> register_cast_function('?int', 'castToIntOrNull');
>=20
> I would quite oppose such a generic implementation, as it might have
> unexpected consequences in other parts of the codebase : it's a global
> configuration set at runtime.
>=20
> I quite like the idea of nullable casting though, as I've come across =
a few
> cases myself where this would have been useful and would have made the =
code
> more concise/readable.
>=20
> Ben
>=20
> On Mon, 8 Apr 2019 at 04:55, Dan Ackroyd <Danack@basereality.com> =
wrote:
>=20
>> On Sat, 6 Apr 2019 at 08:53, Guilliam Xavier =
<guilliam.xavier@gmail.com>
>> wrote:
>>>=20
>>> Hello internals,
>>>=20
>>> David and I would like to open the discussion on our joint RFC:
>>>=20
>>> https://wiki.php.net/rfc/nullable-casting
>>>=20
>>> Mainly, it would enable to use e.g. `(?int)$x` besides `(int)$x`.
>>>=20
>>=20
>> I'm guessing you don't actually have ths function getIntOrNull() in
>> your code-base? To help me understand where this would be useful,
>> could you provide some 'real-world' code where this would be useful?
>>=20
>> By the way, this RFC is a special case of something that could be far
>> more generic. If it was possible to register callbacks to be used =
when
>> casting, people could do something like this:
>>=20
>> function castToIntOrNull($value)
>> {
>>    if ($value =3D=3D=3D null) {
>>        return null;
>>    }
>>=20
>>    return (int)$int;
>> }
>>=20
>> register_cast_function('?int', 'castToIntOrNull');
>>=20
>> $x =3D (?int)getIntOrNull();
>>=20
>>=20
>>> Additionally, it was requested on the mailing list to consider =
adding
>>> support of nullable types to the settype() function,
>>> e.g. settype($variable, "?int")
>>=20
>> Someone probably needs to make an argument for it to be in core,
>> rather than just saying that it's something that could be done.
>>=20
>> cheers
>> Dan
>> Ack
>>=20
>> --
>> PHP Internals - PHP Runtime Development Mailing List
>> To unsubscribe, visit: http://www.php.net/unsub.php
>>=20
>>=20

I=E2=80=99ve come across this pattern (string variable contains a number =
or nothing) myself, but it also then makes me think - if your target =
=E2=80=99type=E2=80=99 is `?int` and you pass an empty string, =
wouldn=E2=80=99t you expect to get `null` rather than `0` ?=20