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Date: Thu, 14 Jun 2018 16:57:17 +0700
Cc: Sara Golemon <pollita@php.net>,
 PHP internals <internals@lists.php.net>
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References: <CAESVnVqm3tVt53bQfxOpQcOMf_2fXhnu9y+42trTfv7zNMONHw@mail.gmail.com> <CAF+90c-HGB-2MbdrCYuQNrNYR4EJ9hAeFaKTW-sh1kwboDd0Kg@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Subject: Re: [PHP-DEV] Strict switch statements
From: php-lists@koalephant.com (Stephen Reay)

Apologies - sending again from on-list address.=20

I=E2=80=99m not overly fond of the `case =3D=3D=3D`

Could it be simply `case` for current behaviour and `strict case` for the ne=
w behaviour?=20

I=E2=80=99d argue that while fall through can cause problems it also has leg=
itimate uses.



Sent from my iPhone



Sent from my iPhone
>> On 14 Jun 2018, at 15:35, Nikita Popov <nikita.ppv@gmail.com> wrote:
>>=20
>> On Thu, Jun 14, 2018 at 6:53 AM, Sara Golemon <pollita@php.net> wrote:
>>=20
>> Just for casual discussion at this point:
>> https://github.com/php/php-src/pull/3297
>>=20
>> switch ($a) {
>> case FOO:
>>     // Works exactly as current behavior.
>>     break;
>> case =3D=3D FOO:
>>    // Nearly identical, though not using the ZEND_CASE optimization.
>>    // Can probably make this equivalent to `case FOO`, but it felt
>> like an interesting direction.
>>    break;
>> case =3D=3D=3D FOO:
>>    // Only triggers if `$a =3D=3D=3D FOO`, no type juggling
>>    break;
>> }
>>=20
>> Love it? Hate it? See obvious flaws?  The implementation is just a
>> rushed proof of concept, not something I've labored over, it may well
>> have bugs.  Certainly wouldn't target anything earlier than 7.4, if at
>> all.
>=20
> I like the general idea here (switch with strict type comparison), but not=

> super fond of the particular syntax and implementation.
>=20
> I think if people want to use strict matching, they'll quite likely want t=
o
> have it on all cases. Something like "strict switch ($expr) {}" or "switch=

> strict ($expr) {}" or "switch (strict $expr) {}" or "switch ($expr) strict=

> {}" or "switch ($expr) { strict; }" or whatever would be preferable in tha=
t
> case.
>=20
> Additionally, switch has the issue of fall-through behavior, which is
> somewhat unexpected and error prone to many people. It might make sense to=

> introduce an entirely new "match" statement that conforms a bit more with
> how switch-like strictures are implemented nowadays. That is, something li=
ke
>=20
> match ($expr) {
>   "foo" =3D> {...},
>   "bar" | "baz" =3D> {...},
> }
>=20
> or similar. This might need some more design work to ensure forward
> compatibility with potential future algebraic datatypes etc.
>=20
> Nikita