[swift-evolution] ternary operator ?: suggestion

[Dennis Lysenko]

Also, +1 to removing ?: ternary in general. It does not match the
atmosphere of Swift. Where you can write:

self.x = a ? b : c
self.y = a ? d : e
self.z = a ? f : g

You could just write

if a {
  self.x = b
  self.y = d
  self.z = f
} else {
  self.x = c
  self.y = e
  self.z = g
}

Now it's easier to scan for what changes when a is true. With
if-expressions, this would scale even better to multiple
conditions/declarations.

On Tue, Dec 15, 2015 at 11:14 AM Dennis Lysenko <dennis.s.lysenko at gmail.com>
wrote:

> Can we just have if-expressions and Xcode indent if-statements the way
> that Ruby style guides suggest?
>
> let x = if y < 0 {
> z * z - 4
> } else {
> 8
> }
>
>
> Works fantastically well in Ruby, for me. Looks a bit strange to the
> untrained eye but that went away for me pretty much the first time I wrote
> one of these. It's:
>
> - More readable than ternary
> - Not shoehorning complex logic onto one line
> - All indented to the same indentation level
>
> And we don't have the 80-char line delimiter or length limit in Swift,
> with Xcode also using a slightly smaller font size than most other IDEs, so
> indentation should not be that much of an issue. Admittedly, ruby style
> dictates two-space indentation which makes this type of code slightly
> shallower.
>
> On Tue, Dec 15, 2015 at 5:34 AM Al Skipp via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>> On 15 Dec 2015, at 06:41, Paul Ossenbruggen via swift-evolution <
>> swift-evolution at swift.org> wrote:
>>
>> Agreed, I was thinking to I really want turn something that was 2
>> characters into 10 and will I really be happy with that at the end of the
>> day. A properly formatted ternary can be quite easy to read, it is when
>> people get sloppy and try to cram too much into one expression that they
>> get really hard to follow. For example,
>>
>>     return (a<b) ? (b<c) ? b : (a<c) ? c : a : (a<c) ? a : (b<c) ? c : b;
>>
>> If formatted like this becomes easier follow the logic (at least to me):
>>
>> return a < b
>> ? b < c
>> ? b
>> : a < c
>> ? c
>> : a
>> : a < c
>> ? a
>> : b < c
>> ? c
>> : b
>>
>>
>> I’m happy to make use of the ternary operator, but never in a nested
>> fashion. It looks neat and succinct on first glance, but is quite
>> impenetrable to read. I don’t think there’s a way to make such nested
>> expressions easily comprehensible. Nested ‘if/else/then’ expressions will
>> be equally bewildering.
>>
>> On a purely stylistic level I think simple, ‘if/then/else’ expressions,
>> would have a more Swift vibe to them than the ternary operator. Well, that
>> would be the case if it didn’t introduce the confusion between expressions
>> and statements.
>>
>> I do still however like the Switch Expressions.
>>
>>
>> I agree. The Switch expression proposal is worth pursuing, it’s something
>> I’d really like to see in the language. One concern I have is that it faces
>> the same dilemma of the ‘if’ expression proposal, that is, how to make the
>> distinction between a statement and an expression unambiguous?
>>
>> Here’s a suggestion, it might be terrible (I’ve not had my third cup of
>> tea of the morning yet), but how about a different keyword? I know, I feel
>> guilty for the suggestion already, but here it is:
>>
>> switch == statement
>> match == expression
>>
>> The syntax you (@Paul) have already suggested for the feature wouldn’t
>> change, but instead of ‘switch’, it’d use the ‘match’ keyword for the
>> expression form. Good, bad, terrible? What do people think?
>>
>> Al
>>
>>
>>
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>
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