[swift-evolution] [idea] errors in properties

[Gor Gyolchanyan]

> On Jul 26, 2017, at 8:21 AM, Ben Rimmington <me at benrimmington.com> wrote:
> 
> Brent Royal-Gordon has written a draft proposal:
> 
> <https://github.com/apple/swift-evolution/pull/218 <https://github.com/apple/swift-evolution/pull/218>>

I totally love it! I’m even OK with wrapping stored properties into computed ones because of willSet and didSet not being able to throw (for the time being anyway).

Brent, hello!
Can you tell me why this proposal of yours is not pushed to review?

>> On 25 Jul 2017, at 21:58, Gor Gyolchanyan via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> This sounds like a challenge 🙂 
>> But seriously, seems like straight-up implementing the feature and then wondering whether or not the pull request will be merged in or rejected is an unnecessary gamble, which is why swift-evolution exists.
>> Haven’t anyone tried to make a proposal for this?
>> I’d gladly look into implementing it myself if I new for sure that my efforts wouldn’t be wasted.
>> 
>>> On Jul 25, 2017, at 11:55 PM, Xiaodi Wu <xiaodi.wu at gmail.com <mailto:xiaodi.wu at gmail.com>> wrote:
>>> 
>>> There have been a number of discussions on the list in this—Google finds a number of these with a search “swift throwing properties site:lists.swift.org <http://lists.swift.org/>”.
>>> 
>>> The “tldr” seems to be that it’s not supported because no one has written code to support it yet.
>>> On Tue, Jul 25, 2017 at 15:29 Gor Gyolchanyan via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> I’ll just cut to the chase:
>>> Why is throwing from get, set, willSet and didSet disallowed?
>>> 
>>> var login: String {
>>> 	willSet throws {
>>> 		guard newValue.count > 5 else {
>>> 			throw LoginError.loginTooSmall
>>> 		}
>>> 	}
>>> }
>>> 
>>> try login = “JebediahKerman” // totally fine
>>> try login = “Bob” // throws `LoginError.loginTooSmall`

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