[swift-evolution] sortBy, minElementBy and maxElementBy methods

[Dave Abrahams]

> On Dec 31, 2015, at 4:14 AM, Tino Heth <2th at gmx.de> wrote:
> 
> 
>> func byComparing<T, U: Comparable>(getComparisonKey: (T)->U) -> (T, T) -> Bool {
>>   return { getComparisonKey($0) < getComparisonKey($1) }
>> }
> I've written something similar to bring file URLs into the order of their creation dates.
> It is a small extension for collection types, and its only downside will disappear as soon as properties are accessible via method calls (afair there is a proposal in the making).
> 
> It was quite a lot fiddling with generics, and I don't have the tiny piece of code on my own computer, but it works in a way that you can do
> let sorted = array.sortUsingAccessor(ElementType.methodThatReturnsComparable)
> Beside the problems with properties, I really liked that approach.

This seems to be essentially the same design as Susan’s, and has the same problem: it requires a new overload for every algorithm that takes a comparison predicate.

-Dave

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20151231/2f169355/attachment.html>