[swift-evolution] ternary operator ?: suggestion

[J. Cheyo Jimenez]

Ha. Disregard. I misread this.

On Sunday, December 13, 2015, J. Cheyo Jimenez <cheyo at masters3d.com> wrote:

> "or we could go with an optional “then” for statements as was suggested by
> Thorsten. "
>
> I don't think this should go in the proposal. An else is alway required in
> a guard statement, an expression should not return an optional imho.
>
>
>
> On Sunday, December 13, 2015, Paul Ossenbruggen via swift-evolution <
> swift-evolution at swift.org
> <javascript:_e(%7B%7D,'cvml','swift-evolution at swift.org');>> wrote:
>
>>
>>
>> On Dec 13, 2015, at 8:11 AM, Jakob Egger <jakob at eggerapps.at> wrote:
>>
>> I really don't like the "if cond then expr1 else expr2".
>>
>> 1) First of all, it's extremely verbose. It's almost as bad as the SQL
>> construct "case when cond then expr1 else expr2 end”.
>>
>>
>> Yeah it adds a few characters overall. What used to be 2 chars now takes
>> 10. Clarity is preferred though by many. I head frequently people telling
>> users to never use ternary operators because they are confusing to read.
>>
>>
>> 2) It makes Swift harder to learn. Newcomers will be confused why you
>> sometimes need to use curly braces and why at other times you need to use
>> the "then" keyword.
>>
>>
>> I did mention this in Alternatives Considered section. By making the else
>> part required, this emphasizes that it is different or we could go with an
>> optional “then” for statements as was suggested by Thorsten.
>>
>>
>> 3) It doesn't help when you want to do multi-line calculations
>>
>>
>> This is the case with the ternary as well, I think it is better to keep
>> it simple.
>>
>>
>> But there is one good side to this proposal: it nests more naturally than
>> the ternary operator:
>> "if cond then expr1 else if cond2 then expr2 else expr3"
>> vs.
>> "cond ? expr1 : (cond2 ? expr2 : expr3)
>>
>> The proposed syntax for the switch statement is so confusing that I
>> really don't think it is a good idea.
>>
>>
>> Not sure why that is, it is essentially the same as the existing switch
>> statement except everything is an expression instead of statements. Is
>> there anything I can do in the examples or documentation to make things
>> clearer?
>>
>>
>> Why not just allow normal if statements to return values?
>> I don't see what's so bad about the following:
>> "let value = if cond {expr1} else {expr2}"
>>
>> This would also extend to multiple lines:
>> let value = if cond {
>>   expr1
>> } else {
>>   let something = Object()
>>   something.doStuff()
>>   something
>> }
>>
>>
>> I answered this with others, also notice how there are braces everywhere?
>> does that really work when you just want to put something on one line. What
>> happens when one of your branches returns void? Expressions are guaranteed
>> to have a result, statements don’t make such a guarantee.
>>
>>
>>
>> Jakob
>>
>> On 13 Dec 2015, at 06:54, Paul Ossenbruggen via swift-evolution <
>> swift-evolution at swift.org> wrote:
>>
>> Hello All,
>>
>> Been sick in bed all day, but decided to try to be productive…
>>
>> I did a rough draft of a proposal for implementing if expressions and
>> switch expressions based upon the discussions we had here. I have tried to
>> keep the scope of the changes as small as possible,  only added one keyword
>> and kept things as similar to the existing language constructs as possible.
>> If anyone wants to help me with this, or has feedback, please let me know,
>>
>> https://github.com/possen/swift-evolution/blob/master/0020.md
>>
>> Thanks,
>> - Paul
>>
>>
>>
>>
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