[swift-evolution] [Idea] Add forced conversion for Error catching pattern matching

[Tyler Fleming Cloutier]

This is actually quite a good solution. It wouldn’t be quite as consistent if I had multiple catch statements for different types before this but it really gets almost all of the way there. Thanks!

> On Mar 21, 2016, at 6:20 PM, Michel Fortin <michel.fortin at michelf.ca> wrote:
> 
> Le 20 mars 2016 à 16:26, Tyler Fleming Cloutier via swift-evolution <swift-evolution at swift.org> a écrit :
>> 
>> Would it be wise to allow force conversion for the cases in which the developer believes the match is exhaustive? ie
>> 
>> do {
>>    let action = chooseAction(game)
>>    game = try game.applyAction(action)
>> } catch let e as ActionError {
>>    game.failedAction = e
>> } catch _ {
>>    fatalError(“This is an unfortunate bit of noise :/")
>> }
>> 
>> becomes
>> 
>> do {
>>    let action = chooseAction(game)
>>    game = try game.applyAction(action)
>> } catch let e as! ActionError {
>>    game.failedAction = e
>> }
> 
> If you move the cast on the next line it'll compile and do what you want with exactly the same amount of code:
> 
> 	do {
> 	    let action = chooseAction(game)
> 	    game = try game.applyAction(action)
> 	} catch let e {
> 	    game.failedAction = e as! ActionError
> 	}
> 
> 
> -- 
> Michel Fortin
> https://michelf.ca
>