Property for Double and CGFloat

Question

Created Jan ’16

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Suppose I want a property to tell me whether an arbitrary number is an integer. If the number is a Double, I can just use this:

 extension Double {
  var isInteger: Bool {
  return Double(self) == Double(Int(self))
  }
}

Of course I can make the same extension for CGFloat, or just cast a CGFloat to a Double. That's easy enough, but I'm curious: Is there a way of defining a function that will work for both Double and CGFloat without a cast? I've been working my way through the Protocols chapter of The Swift Programming Language and I'm wondering if there's a way of doing it with a protocol.

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Answer 1

OOPer OP

Jan ’16

It's not easy under the current Swift type system.

My best proposal is something like this:

 protocol IntegerCheckableFloatType: FloatLiteralConvertible, Equatable {
    func % (lhs: Self, rhs: Self) -> Self
    var isInteger: Bool {get}
}
extension IntegerCheckableFloatType {
    var isInteger: Bool {
        return self % 1.0 == 0.0 as Self
    }
}
extension Double: IntegerCheckableFloatType {}
extension CGFloat: IntegerCheckableFloatType {}
extension Float: IntegerCheckableFloatType {}
(123.4).isInteger //->false
(123.0).isInteger //->true

0

	extension Double {
	var isInteger: Bool {
	return Double(self) == Double(Int(self))
	}
	}

	protocol IntegerCheckableFloatType: FloatLiteralConvertible, Equatable {
	func % (lhs: Self, rhs: Self) -> Self
	var isInteger: Bool {get}
	}
	extension IntegerCheckableFloatType {
	var isInteger: Bool {
	return self % 1.0 == 0.0 as Self
	}
	}
	extension Double: IntegerCheckableFloatType {}
	extension CGFloat: IntegerCheckableFloatType {}
	extension Float: IntegerCheckableFloatType {}
	(123.4).isInteger //->false
	(123.0).isInteger //->true