> On Feb 8, 2017, at 12:09 PM, Daryle Walker via swift-evolution
> <[email protected]> wrote:
>
> I’ve been trying to get the maximum of a list of counts. I started by using
> “myCollection.map { $0.myCountProperty }.reduce(0, max)”. Then I thought I
> should really use the value closest to negative infinity as the base. The
> problem is how to get that value. The current hard-coded “0” works because
> the count type ultimately aliases “Int”, but shouldn’t have to count on that.
> I put in “MyCountType.min”, where “MyCountType” is hard coded from the docs
> of “myCountProperty”, but I shouldn’t have to do that either.
>
> There is a “type(of:)” global function, which I did use. But not only did I
> have to make up an expression to go in there, its return value, some sort of
> meta-type stuff I don’t understand, can’t be used on the right side of a
> “typealias” construct. I ultimately used “let lowestCount = type(of:
> anElement.myCountProperty).min” to get what I needed.
type(of:) does evaluate its argument, since for things like classes you need to
know the value you're asking of a type for. However, you can avoid hardcoding a
type at all in this case by using contextual lookup:
myCollection.map { $0.myCountProperty }.reduce(.min, max)
`.foo` will look up static members inside the contextual type of the expression.
-Joe
_______________________________________________
swift-evolution mailing list
[email protected]
https://lists.swift.org/mailman/listinfo/swift-evolution
