自定义可识别协议在Swift中实现隐式构造

Question

AFAIK,Swift class可以通过符合的字面值来分配ExpressibleBy*Literal.

例如,类A可以Int像这样分配,这类似于隐式构造C++

class A : ExpressibleByIntegerLiteral {
    typealias IntegerLiteralType = Int

    required init(integerLiteral value: A.IntegerLiteralType) {
    }
}

var a: A = 1

现在,我可以将ExpressibleBy*协议扩展到任何我的自定义类型吗？

protocol ExpressibleByMyTypeLiteral {
    associatedtype MyType

    init(literal value: Self.MyType) 
}

class B {
}

class A : ExpressibleByIntegerLiteral, ExpressibleByMyTypeLiteral {
    //ExpressibleByIntegerLiteral
    typealias IntegerLiteralType = Int

    required init(integerLiteral value: A.IntegerLiteralType) {
    }

    //ExpressibleByMyTypeLiteral
    typealias MyType = B

    required init(literal value: A.MyType) {
    } 
}

var a: A = 1
var aMyType: A = B() //Compiler Error: Cannot convert value of 'B' to specified type 'A'