> On Aug 5, 2016, at 7:36 PM, Erica Sadun <er...@ericasadun.com> wrote:
>
> On Aug 5, 2016, at 8:10 PM, Kevin Ballard <ke...@sb.org
> <mailto:ke...@sb.org>> wrote:
>>
>>>
>>> On Aug 5, 2016, at 5:16 PM, Erica Sadun <er...@ericasadun.com
>>> <mailto:er...@ericasadun.com>> wrote:
>>>
>>>
>>>> On Aug 5, 2016, at 4:19 PM, Douglas Gregor via swift-evolution
>>>> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
>>>>
>>>>>
>>>>> On Aug 5, 2016, at 12:59 PM, Kevin Ballard via swift-evolution
>>>>> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
>>>>>
>>>>> If all you want to do is get the localized description, then you can just
>>>>> say `(error as NSError).localizedDescription`.
>>>>
>>>> Just ‘error.localizedDescription’ works now. That was part of SE-0112.
>>>>
>>>> - Doug
>>>
>>> Would it kill to allow:
>>>
>>> let err = NSError()
>>> err.localizedDescription = "bad things happen"
>>> throw err
>>>
>>> or even
>>>
>>> throw NSError("Bad things happen")
>>>
>>> for lightweight use? I ended up refactoring entirely to enum : Error
>>> because Swift yelled at me for using NSError(): "this results in an invalid
>>> NSError instance. It will raise an exception in a future release. Please
>>> call errorWithDomain:code:userInfo: or initWithDomain:code:userInfo:. This
>>> message shown only once."
>>>
>>> enum Errors: Error {case bad}
>>> Errors.bad._code // 0
>>> Errors.bad._domain // "Errors"
>>> Errors.bad._userInfo // Optional({})
>>> Errors.bad.localizedDescription // "The operation couldn’t be completed.
>>> (Errors error 0.)"
>>>
>>> Bleh.
>>
>> NSErrors need a domain/code. It doesn’t make much sense to throw one without
>> it. And besides, there’s a fairly trivial solution for doing what you want
>> to do:
>>
>> struct GenericError: LocalizedError {
>> let message: String
>> init(_ message: String) {
>> self.message = message
>> }
>> var errorDescription: String? {
>> return message
>> }
>> }
>>
>> Now you can just say `throw GenericError(“Bad things happen”)`.
>>
>> -Kevin Ballard
>
> I know I can build workarounds but if we're going to have the
> error.localizedDescription, making it an initializable/assignable property
> just seems like a nice thing™. Why can't we have nice things™?
I don’t actually think it’s a nice thing™ to have it be assignable like you
ask, because we should be encouraging people to use typed errors. You may as
well just ask for String to conform to Error (in fact, you could just add that
conformance yourself and skip the GenericError wrapper entirely).
-Kevin
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