What is wrong with: if let x = x where x > 10, y != 5, let z = z where z != x
Just as a contrived example? Brandon > On May 31, 2016, at 4:03 PM, Xiaodi Wu <[email protected]> wrote: > >> On Tue, May 31, 2016 at 2:59 PM, Brandon Knope <[email protected]> wrote: >> Except "b" is the main focus of the where clause and b was just in the >> preceding if condition. >> >> I feel like we are trying to find ways to break the current where clause >> even though we've enjoyed it for almost a year now. I had no idea it was >> problematic and restrictive. I thought it made its intent very >> clear...leading to very readable code. >> >> Pretty soon almost every construct but conditionals will be allowed to have >> where clauses, and THAT seems inconsistent to me. >> >> ...what exactly is the current problem? Can someone show me a real world >> example?? I've already forgotten it in all of this discussion -_- > > The origin of the problem is a simple question: how does one test for > something unrelated to the variable that's bound in an `if let` statement? > The answer is: in today's Swift, any such test after the first `let` must > come after `where`. This is problematic and restrictive because one is forced > to imply a semantic relationship that doesn't exist. > >> Brandon >> >>> On May 31, 2016, at 3:47 PM, Xiaodi Wu via swift-evolution >>> <[email protected]> wrote: >>> >>> >>> >>> On Tue, May 31, 2016 at 2:45 PM, Christopher Kornher via swift-evolution >>> <[email protected]> wrote: >>>>>> >>>>>> Not allowed: >>>>>> … >>>>>> let a = a >>>>>> let b = b where b > 10 && a > 5 >>>>> >>>>> Why would this not be allowed by your rule? You're making use of `b` in >>>>> your where clause. As I demonstrated above, essentially any assertion can >>>>> be rewritten to work around your rule. In general: >>>> >>>> It is not allowed because ‘a’ is defined in the line above. It must be >>>> defined in the ‘if let’ associated with the where in which it is mentioned. >>> >>> That's a much more restrictive where clause than you proposed earlier. >>> You'd not be able to write: >>> >>> ``` >>> let b = b where b > anyOtherVariable >>> ``` >>> >>> _______________________________________________ >>> swift-evolution mailing list >>> [email protected] >>> https://lists.swift.org/mailman/listinfo/swift-evolution >
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