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.’;
}

-John


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