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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