Hi David,
I have been using ?( as kind of a more general meaning that there is a question
here not that ? is just for optionals. I am fine with using some other
character or word if it expresses the idea that the expression returns one of
the results based upon the control parameter. ? is kind of established for the
ternary though. Any word should be very short. In the alternatives considered I
talk about using if(, switch(, select( would that be preferable? I am still
hoping to keep it really short though. Other than using the words as shown, i
am having a hard time coming up with something that would be better than ?.
- Paul
> On Dec 23, 2015, at 10:39 PM, David Waite via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> My only issue (barring any longer term plan to move toward everything being
> an expression) is that the question mark already has many uses in the
> language. If we aren’t supporting the C-style ternary operator syntax, I
> don’t know if there is a good reason anymore to use ‘?’ considering its heavy
> use around optionals.
>
> -DW
>
>> On Dec 23, 2015, at 2:05 PM, Rainer Brockerhoff via swift-evolution
>> <swift-evolution@swift.org> wrote:
>>
>> 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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>> swift-evolution@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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