[swift-evolution] Add unless/if single line syntax
Etan Kissling
kissling at oberon.ch
Mon Dec 14 05:53:41 CST 2015
Sorry,
return unless(username.text.characters.count > 0) {
return nil
}
> On 14 Dec 2015, at 12:53, Etan Kissling <kissling at oberon.ch> wrote:
>
> It's not the same, OP wants to return nil.
>
> So you have to write
>
> return unless(username.text.characters.count > 0) {
> return
> }
>
> and if you miss the first return, you just introduced a bug.
>
>
> Etan
>
>> On 12 Dec 2015, at 18:17, James Campbell via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>
>> So
>>
>> guard username.text.characters.count > 0 else {
>> return
>> }
>> could be expressed as
>> unless(username.text.characters.count > 0) {
>> return
>> }
>> I think the second is much easier to read :)
>>
>> On Sat, Dec 12, 2015 at 4:28 PM, Al Skipp via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> Top marks!
>>
>> unless(condition) { print("condition was false") }
>>
>> The feature implemented in the language. What’s not to like?
>>
>>> On 12 Dec 2015, at 16:20, Tommy van der Vorst via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>
>>> Oops, that should be just:
>>>
>>> public func unless(expression: Bool, block: () -> ()) {
>>> if !expression {
>>> block()
>>> }
>>> }
>>>
>>>> Op 12 dec. 2015, om 17:17 heeft Tommy van der Vorst via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> het volgende geschreven:
>>>>
>>>> Or, use something like this:
>>>>
>>>> public func unless(expression: @autoclosure () -> Bool, block: () -> ()) {
>>>> if !expression {
>>>> block()
>>>> }
>>>> }
>>>>
>>>> unless(..expression..) {
>>>> ...code...
>>>> }
>>>>
>>>> /T
>>>>
>>>>> Op 12 dec. 2015, om 17:08 heeft Al Skipp via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> het volgende geschreven:
>>>>>
>>>>> If at all possible I think it’s best to avoid adding keywords to the language. Instead of ‘unless', you could do:
>>>>>
>>>>> public func not(bool: Bool) -> Bool { return !bool }
>>>>>
>>>>> if not(condition) { print("condition was false") }
>>>>>
>>>>> Not terrible ¯\_(ツ)_/¯
>>>>>
>>>>>
>>>>>> On 12 Dec 2015, at 15:48, Matthew Johnson via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>
>>>>>> I’m not sure about the single line aspect of this proposal, but I am a big proponent of “unless” and “until” as complements to “if” and “while”. They greatly improve readability over "if !(expression)” and “while !(expression)” IMHO.
>>>>>>
>>>>>>> On Dec 12, 2015, at 9:45 AM, Arthur Ariel Sabintsev via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>>
>>>>>>> For your specific example, I'd 100% use the guard statement. It achieves the same result.
>>>>>>>
>>>>>>> -1 from me.
>>>>>>> On Sat, Dec 12, 2015 at 9:43 AM J. Cheyo Jimenez via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>> -1 from me. I think I would rather have an if-then expression that would handle both False and True cases.
>>>>>>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001944.html <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001944.html>
>>>>>>>
>>>>>>> Also, in most cases I feel that guard would be a better choice.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sat, Dec 12, 2015 at 5:39 AM, James Campbell via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>> I propose adding the unless and if statements from ruby.
>>>>>>>
>>>>>>> Return false if james = nil
>>>>>>>
>>>>>>> This returns false if the variable James is nil
>>>>>>> . This line does it unless james is nil:
>>>>>>>
>>>>>>> Return false unless james = nil
>>>>>>>
>>>>>>> This has been really handy when working in ruby, reduces lines and pyramids of doom
>>>>>>>
>>>>>>> Sent from my iPhone
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>>>>>>>
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>>>>>>
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>>
>>
>> --
>> Wizard
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