[swift-evolution] Warning when omitting default case for imported enums

[Rien]

If you don’t want the default case, and if you like a warning free compilation, you need a way to suppress the warning.

Regards,
Rien

Site: http://balancingrock.nl
Blog: http://swiftrien.blogspot.com
Github: http://github.com/Balancingrock
Project: http://swiftfire.nl





> On 07 Feb 2017, at 19:42, Tanner Nelson <tanner at qutheory.io> wrote:
> 
> I don't understand the part about warning suppression. The warning would go away when you add the default case. 
> 
> Sent from my iPhone
> 
>> On Feb 7, 2017, at 16:25, Rien <Rien at Balancingrock.nl> wrote:
>> 
>> -1
>> 
>> Reason 1: the “negative” behaviour you describe is actually exactly what I want to happen.
>> Reason 2: Introducing a warning would also necessitate a warning suppression in order to have your code compile without warnings. But when you suppress, the purpose of the warning is nul and void.
>> 
>> PS: I would suggest not to use an enum in cases where this is really annoying and replace the enums with constants.
>> 
>> Regards,
>> Rien
>> 
>> Site: http://balancingrock.nl
>> Blog: http://swiftrien.blogspot.com
>> Github: http://github.com/Balancingrock
>> Project: http://swiftfire.nl
>> 
>> 
>> 
>> 
>> 
>>> On 07 Feb 2017, at 16:12, Tanner Nelson via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> Hello Swift Evolution,
>>> 
>>> I'd like to propose that a warning be emitted when default cases are omitted for enums from other modules. 
>>> 
>>> What this would look like:
>>> 
>>> OtherModule:
>>> ```
>>> public enum SomeEnum {
>>>   case one
>>>   case two
>>> }
>>> 
>>> public let global: SomeEnum = .one
>>> ```
>>> 
>>> executable:
>>> ```
>>> import OtherModule
>>> 
>>> switch OtherModule.global {
>>>   case .one: break
>>>   case .two: break
>>>   ^~~~~ ⚠︎ Warning: Default case recommended for imported enums. Fix-it: Add `default: break`
>>> }
>>> ```
>>> 
>>> Why:
>>> 
>>> Allowing the omission of a default case in an exhaustive switch makes the addition of a new case to the enum a breaking change. 
>>> In other words, if you're exhaustively switching on an enum from an imported library, the imported library can break your code by adding a new case to that enum (which the library authors may erroneously view as an additive/minor-bump change).
>>> 
>>> Background:
>>> 
>>> As a maintainer of a Swift framework, public enums have been a pain point in maintaining semver. They've made it difficult to implement additive features and have necessitated the avoidance of enums in our future public API plans.
>>> 
>>> Related Twitter thread: https://twitter.com/tanner0101/status/796860273760104454
>>> 
>>> Looking forward to hearing your thoughts.
>>> 
>>> Best,
>>> Tanner
>>> 
>>> Tanner Nelson
>>> Vapor 
>>> +1 (435) 773-2831
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> swift-evolution mailing list
>>> swift-evolution at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>