On Thu, Sep 17, 2015 at 5:52 PM, John Bafford <jbaff...@zort.net> wrote:
> On Sep 17, 2015, at 19:16, Bob Weinand <bobw...@hotmail.com> wrote:
>>
>>> Am 18.09.2015 um 01:06 schrieb Rowan Collins <rowan.coll...@gmail.com>:
>>>
>>> This has come up in passing a few times recently, but I'm not sure there's
>>> ever been a dedicated discussion of it: would it be useful for PHP to have
>>> a built-in Enumeration type, and if so, how should it look?
>>
>> I like enums in general, but I'd like to note that there's already a RFC in
>> draft by Levi:
>>
>> https://wiki.php.net/rfc/enum <https://wiki.php.net/rfc/enum>
>>
>> As far as I know, the RFC is already fairly final and just lacks an
>> implementation.
>>
>> So, I'd consider bikeshedding an actual RFC first.
>
>
> If we’re bikeshedding, one feature I would really like to see, with
> typehinting, is warnings if all cases of an enum aren’t handled in a switch.
> So, for example, given our example Weekdays enum, if I wrote this code:
>
> switch(Weekday $someWeekday) {
> case Weekday::MONDAY: break;
> case Weekday::TUESDAY: break;
> }
>
> By providing the typehint, I’m indicating that I want to get a warning/error
> that the switch does not cover all enum values. This would be very handy if
> an enum value is added after initial development and someone misses a switch
> statement in cleanup.
>
> The typehint would also allow generating a warning if someone did something
> like
>
> switch(Weekday $someWeekday) {
> //case … all the weekdays: break;
> case ‘I am not a Weekday’: echo ‘Generate a fatal error here because
> string is not a Weekday.’;
> }
I've looked into this but not in the same syntax you've provided. I
was exploring a `match` construct that has different semantics:
match ($foo) {
case Weekday::Monday: {
echo "Monday";
} // it is not possible to fall-through with match/case
case Weekday::Tuesday: echo Monday; // single expression
doesn't need braces
} // if it hits the end without a match a runtime error will be emitted
I think this fits into the dynamic behavior of PHP a little better
than forcing a case for each enum value at compile-time, even if it
was possible (I suspect it is not).
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