[swift-evolution] [Pitch] Guard/Catch

Beta rwidmann at apple.com
Wed Jul 5 13:28:31 CDT 2017

> On Jul 5, 2017, at 10:30 AM, Soroush Khanlou via swift-evolution <swift-evolution at swift.org> wrote:
> I’d like to propose a guard/catch construct to the language. It would allow code to use throwing functions and handle errors fully, without straying from a happy path. do/catch can be a bit heavy-handed sometimes, and it would be nice to be able to handle throwing functions without committing to all the nesting and ceremony of do/catch.

The nesting and ceremony, to me, were part of Swift’s philosophy of making error handling explicit.  Merging catch blocks into guards saves you maybe 3-10 lines if you intended to actually handle the error(s), otherwise this effectively try?’s  into a failable pattern match.  At which point, you have to wonder if the error-throwing function you wrote wouldn’t be better off just returning an Optional if you’re going to discard the semantic content of the error.

~Robert Widmann

> Full proposal, which discusses all the corner cases and alternatives:
> https://gist.github.com/khanlou/8bd9c6f46e2b3d94f0e9f037c775f5b9 <https://gist.github.com/khanlou/8bd9c6f46e2b3d94f0e9f037c775f5b9>
> Looking forward to feedback!
> Soroush
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