On 22/12/15 16:50 , swift-evolution-requ...@swift.org wrote:
> Date: Tue, 22 Dec 2015 10:07:26 -0800
> From: Jordan Rose <jordan_r...@apple.com>
> To: Thorsten Seitz <tseit...@icloud.com>
> Message-ID: <2d35f5bd-3ddf-43c3-a461-14fb65530...@apple.com>
>
> I think this is a good point. We definitely want to keep the boolean
> ternary operator compact for the simple cases, and that may be at
> odds with a general switch expression (with multi-case pattern
> match).
+1 for a compact form.
I use the boolean ternary a lot, and I'd really dislike complicating it
with keywords or expanding it into a multiline construct with cases.
Nesting is of course its main problem.
> Date: Tue, 22 Dec 2015 10:53:50 -0800
> From: Paul Ossenbruggen <pos...@gmail.com>
> Message-ID: <7c5eca99-4527-4995-8503-215f294cc...@gmail.com>
>
> • it is hard to tell when a ternary begins and ends, especially when nested.
At first I liked Paul's original proposal of
let a = ?(x == y: a, b)
but I now think something intermediate like
let a = x == y ?(a, b)
would look better; it does take care of nesting. For more clarity one
could always write
let a = (x == y) ?(a, b)
> • It is not until you get to the question mark that you realize it is a
> ternary.
I think that's actually a good thing. You (or the parser) have found a
boolean expression and when the ?( appears you understand the result is
fed into a selector. Were the ? and ( separate you could consider ? as a
binary operator accepting a boolean and a 2-tuple.
Today, using ? as an operator appears not to be allowed, but
public func ??<T> (left:Bool, right: (T, T)) -> T {
if (left) {
return right.0
}
return right.1
}
already works:
let a = (x == y) ?? (a, b)
runs as expected. Downside, no @autoclosure on tuple items.
IOW, you shouldn't be too surprised finding a binary operator after an
expression :-)
--
Rainer Brockerhoff <rai...@brockerhoff.net>
Belo Horizonte, Brazil
"In the affairs of others even fools are wise
In their own business even sages err."
http://brockerhoff.net/blog/
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