我很好奇在Scala中这种情况的最佳解决方案是什么:
class MyClass private (x: Any, y: Int) {
def this(x: Int, y: Int) = this(x, y)
def this(x: String, y: Int) = this(x, y)
}
val x0 = new MyClass(1, 1)
val x1 = new MyClass("1", 1)
//val x2 = new MyClass(1.0, 1) // Correctly doesn't typecheck
下面的错误对我来说没有多大意义,因为在辅助构造函数之前定义了一个可行的构造函数:
Error:(3, 31) called constructor's definition must precede calling constructor's definition
def this(x: Int, y: Int) = this(x, y)
^
对于更多的上下文,我实际上试图处理Scala.js中的JavaScript api,其函数可以是String
或js.Object
的参数,但我认为这体现了问题。
明确地将类型归为Any
将有助于:
class MyClass private (x: Any, y: Int) {
def this(x: Int, y: Int) = this(x: Any, y)
def this(x: String, y: Int) = this(x: Any, y)
}
在您的例子中,构造函数将递归地调用自己,这显然是没有意义的。
我从来没有使用过Scala-js,但是这可以解决你的问题吗:
class MyClass private (x: Any, y: Int)
object MyClass{
def apply(x:Int,y:Int) = new MyClass(x,y)
def apply(x:String, y:Int) = new MyClass(x,y)
}
val x0 = MyClass(1, 1)
val x1 = MyClass("1", 1)
//val x2 = new MyClass(1.0, 1) // Correctly doesn't typecheck