[swift-users] Implementing signum

[Rick Mann via swift-users]

I'm trying to do this:

protocol Signumable
{
        func sgn() -> Self
}

extension Signumable
{
        func
        sgn()
                -> Self
        {
                let pos = 0 < self              //  Error
                let neg = self < 0              //  Error
                let p = pos ? Self(1) : Self(0)
                let n = neg ? Self(1) : Self(0)
                return p - n
        }
}


extension Double : Signumable {}

But I get

Binary operator '<' cannot be applied to operands of type 'Int' and 'Self'

I figure there should be additional constraints on Signumable.

Help would be much appreciated!


-- 
Rick Mann
rm...@latencyzero.com


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