Re: Let's discuss enums!

> Am 18.09.2015 um 01:52 schrieb John Bafford <jbafford@zort.net>: > > On Sep 17, 2015, at 19:16, Bob Weinand <bobwei9@hotmail.com> wrote: >> >>> Am 18.09.2015 um 01:06 schrieb Rowan Collins <rowan.collins@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 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... Bob