如何重载scala函数apply方法

发布于 2024-12-03 09:26:43 字数 515 浏览 0 评论 0原文

正确的语法是将 withLoaner 参数移动到重载的 apply 方法？我尝试了以下几个版本均未成功。另外，非常感谢对我的错误概念的任何见解。

def withLoaner = new {
  def apply(n:Int, op: Int => String):String = (1 to n).map(op).mkString("\n")
  def apply(n:Int, op: () => String):String = apply{n, i:Int => op()} // no compile
  def apply(op: () => String):String = apply{1, i:Int => op()} // no compile
}

原文

As a follow on to: scala loan pattern, optional function param

What would the proper syntax be to move the withLoaner param to overloaded apply methods? I've tried several versions of the following unsuccessfully. Also, any insights into my error conceptually very appreciated.

def withLoaner = new {
  def apply(n:Int, op: Int => String):String = (1 to n).map(op).mkString("\n")
  def apply(n:Int, op: () => String):String = apply{n, i:Int => op()} // no compile
  def apply(op: () => String):String = apply{1, i:Int => op()} // no compile
}

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一杆小烟枪 2024-12-10 09:26:43

传递多个参数时，必须使用括号将它们括起来。使用 {} 仅适用于单个参数。

此外，在使用函数文字时，如果指定类型，则必须将所有函数参数放在括号内。

所以，

def withLoaner = new {
  def apply(n:Int, op: Int => String):String = (1 to n).map(op).mkString("\n")
  def apply(n:Int, op: () => String):String = apply(n, i => op()) // no type on i
  def apply(op: () => String):String = apply(1, (i: Int) => op()) // parenthesis around parameters
}

When passing multiple parameters, you must use parenthesis around them. Using {} only works for single parameters.

Also, when using function literals, if you specify type, you have to put all of the functions parameters inside parenthesis.

So,

def withLoaner = new {
  def apply(n:Int, op: Int => String):String = (1 to n).map(op).mkString("\n")
  def apply(n:Int, op: () => String):String = apply(n, i => op()) // no type on i
  def apply(op: () => String):String = apply(1, (i: Int) => op()) // parenthesis around parameters
}

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