[swift-evolution] Move placement of 'throws' statement

[Dave Abrahams]

on Mon Dec 26 2016, thislooksfun <swift-evolution at swift.org> wrote:

> Hello Swifters,
>
> I've been writing a lot more Swift code recently, and I have found
> that the default placement of the 'throws' declaration is often
> confusing, especially to those of us switching from languages where
> the type of errors thrown is explicitly defined (like Java)
>
> For example,
> // This is pretty clear, this can throw an error
> func foo() throws
> { ... }
>
> // Also pretty clear, this returns a String
> func bar() -> String
> { ... }
>
> // Confusing. Does this throw a String? Does it return a String? Does it do both?
> // I personally keep reading this as 'this can throw a String'
> func baz() throws -> String
>
> // Equivalent code in Java (not a model, just for clarification of why the above is confusing)
> String baz() throws StringFormatException
> I therefore suggest either tweaking the syntax around, or moving, the
> `throws` keyword to avoid this confusion.
>
> Some ideas I've had:
> // Add a comma to separate them
> func baz() throws, -> String
>
> // Move `throws` to the end
> func baz() -> String throws

I agree that reads much better.

> // Change it to a prefix modifier (like `mutating`)
> throwing func baz() -> String
> I'm still not sold on any of the above syntaxes, but I would love to hear your feedback.
>
> This would affect existing code, but it would be a fairly small change
> that would result in very large readability improvements, especially
> for newcomers, and especially for those coming for a language such as
> Java.
>
> -thislooksfun (tlf)
>
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>

-- 
-Dave