Why add all those algorithms when you can write this
func byComparing<T, U: Comparable>(getComparisonKey: (T)->U) -> (T, T) -> Bool {
return { getComparisonKey($0) < getComparisonKey($1) }
}
peoples.sort(byComparing { $0.name })
?
-Dave
> On Dec 30, 2015, at 10:38 PM, Susan Cheng via swift-evolution
> <swift-evolution@swift.org> wrote:
>
>
> Consider the follows:
>
> struct Person {
>
> var name: String
> var age: Int
> }
>
> let peoples = [Person(name: "Hawk", age: 24), Person(name: "Andrew", age: 23)]
>
> let youngest = peoples.minElement { $0.age < $1.age }
>
> print(youngest?.name)
>
> it's silly that we always have to write the code like { $0.some < $1.some }
> or { some($0) < some($1) }
>
> so, we should add those methods to stdlib:
>
> extension SequenceType {
> /// Returns the minimum element in `self` or `nil` if the sequence is
> empty.
> ///
> /// - Complexity: O(`elements.count`).
> ///
> @warn_unused_result
> public func minElement<R : Comparable>(@noescape by: (Generator.Element)
> throws -> R) rethrows -> Generator.Element? {
> return try self.minElement { try by($0) < by($1) }
> }
> /// Returns the maximum element in `self` or `nil` if the sequence is
> empty.
> ///
> /// - Complexity: O(`elements.count`).
> ///
> @warn_unused_result
> public func maxElement<R : Comparable>(@noescape by: (Generator.Element)
> throws -> R) rethrows -> Generator.Element? {
> return try self.maxElement { try by($0) < by($1) }
> }
> }
>
> public extension MutableCollectionType {
>
> /// Return an `Array` containing the sorted elements of `source`.
> /// according to `by`.
> ///
> /// The sorting algorithm is not stable (can change the relative order of
> /// elements that compare equal).
> @warn_unused_result(mutable_variant="sortInPlace")
> func sort<R : Comparable>(@noescape by: (Generator.Element) -> R) ->
> [Generator.Element] {
> return self.sort { by($0) < by($1) }
> }
> }
>
> public extension MutableCollectionType where Self.Index :
> RandomAccessIndexType {
>
> /// Sort `self` in-place according to `by`.
> ///
> /// The sorting algorithm is not stable (can change the relative order of
> /// elements that compare equal).
> mutating func sortInPlace<R : Comparable>(@noescape by:
> (Generator.Element) -> R) {
> self.sortInPlace { by($0) < by($1) }
> }
> }
>
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