[swift-dev] [Proposal] RangeReplaceableCollection should inherits from MutableCollection

[frogcjn at 163.com]

String should be some kind of MutableCollection. if we really want to restrict subscript of String should be { get } only, then we should consider make some extension methods of MutableCollection should available on SubrangeReplaceablecollection too.

For example:
> 
> var c = [1, 2, 3, 4]
> print(c.reversed()) // OK
> 
> 
> var d = "1234"
> print(d.reversed()) // OK

They are both fine.

> var a = [1, 2, 3, 4]
> a.reverse()
> print(a) // OK
> 
> 
> var b = "1234"
> b.reverse() // no function
> print(b)

But this is weird.

String has String.reversed() function,
but it does not have String.reverse() function which is MutableCollection only.


I think, MutableCollection.reverse(), swapAt(_:_:), .partition(by:), sort(by:), should also be available with RangeReplaceableCollection.

> 在 2017年12月6日，06:55，Dave Abrahams <dabrahams at apple.com> 写道：
> 
> 
> 
> Sent from my iPhone
> 
>> On Dec 5, 2017, at 12:19 AM, Cao, Jiannan via swift-dev <swift-dev at swift.org> wrote:
>> 
>> 
>> But, I mean, what subscript (restrict to the length) could do is subset of p replaceSubrange could do, right?
> 
> True but that would imply the opposite of the refinement relationship you’re suggesting. A derived protocol has to have a subset of the behavior of the protocol it refines.
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