> On Sep 17, 2015, at 20:06, Bob Weinand <bobw...@hotmail.com> wrote:
>
>> Am 18.09.2015 um 01:52 schrieb John Bafford <jbaff...@zort.net>:
>>
>> 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.’;
>> }
>
> So, you mean like an implicit
> default: throw Error("Unhandled enum value Weekday::FRIDAY");
>
> Possible, but then you also just can add
> default: assert(0);
> instead of a typehint.
>
> At compile-time won't be really possible, as, when the switch is encountered,
> the enum might not yet have been loaded. That's one of the consequences of
> PHP's lazy inclusion system...
Compile-time might not be possible, true, but at least this would provide for
runtime checks, and the benefit of explicitly stating intention is that
intention is explicitly stated. Also, it would allow the sort of errors I’m
proposing be generated to all be standardized across all applications, which
would allow fancy error handlers, such as with Symfony, to offer helpful
context-specific suggestions. Also, it’d provide static analyzers additional
information by which to provide correctness alerts.
-John
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