[swift-users] protocol definition question

[torquato]

Hello everyone!

My first mail on the list. That means I can't reply directly to the mail 
I found in the archive.

In addition to what Kevin already suggested here 
https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20171211/006743.html 
there is another more generic solution to circumvent the problem that 
you have to specify a concrete type for the array element.
You could use a second associated type in the protocol definition.

This is how it could look like:



protocol RawBits {
     associatedtype RawElement: FixedWidthInteger
     associatedtype RawValue = RawElement
     var rawValue: RawValue { get set }
}



extension RawBits where RawElement: UnsignedInteger, RawValue == 
Array<RawElement> {
     func testArray() {
         print("RawElement: \(RawElement.self) RawValue: \(RawValue.self)")
     }
}

extension RawBits where RawElement: UnsignedInteger, RawValue == 
RawElement {
     func testUnsigned() {
         print("RawElement: \(RawElement.self) RawValue: \(RawValue.self)")
     }
}



struct RBits<RawElement: FixedWidthInteger>: RawBits {
     var rawValue: RawValue
}

struct RBitsX<RawElement: FixedWidthInteger>: RawBits {
     var rawValue: [RawElement]
}



var rb = RBits(rawValue: 42 as UInt32)
rb.testUnsigned() // RawElement: UInt32 RawValue: UInt32

var rbx = RBitsX(rawValue: [1 as UInt8, 2, 3])
rbx.testArray() // RawElement: UInt8 RawValue: Array<UInt8>