Swift Standard Library: Optional should NOT be Comparable

Originator:fabian.ehrentraud
Number:rdar://21459774 Date Originated:19-Jun-2015 03:26 PM
Status:Open Resolved:
Product:Developer Tools Product Version:Xcode 7 beta 1
Classification:Crash/Hang/Data Loss Reproducible:Always
 
Summary:
Optionals can be compared via relational operators `<`, `<=`, `>` and `>=`. This leads to unexpected results.

Steps to Reproduce:
* `nil < 0` compiles and returns `true`.

Expected Results:
This should not even compile, as comparing .None to .Some via the given relational operators has no proper meaning.

Actual Results:
It compiles and might cover up a programming error.

Notes:
I would recommend removing the following methods from the Swift Standard Library:

func <<T : Comparable>(lhs: T?, rhs: T?) -> Bool
func <=<T : Comparable>(lhs: T?, rhs: T?) -> Bool
func ><T : Comparable>(lhs: T?, rhs: T?) -> Bool
func >=<T : Comparable>(lhs: T?, rhs: T?) -> Bool

Comments

What about making the return type of those a Bool?? It would return a value only when both Optionals are Some.

By DeFrenZ at June 19, 2015, 1:33 p.m. (reply...)

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