小编And*_*osa的帖子

我有以下类型:

trait Monster {
    fn attack(&self);
    fn new(int) -> Self;
}

struct CookiesMonster {
    cookies: int,
    hungry_level: int,
}

impl Monster for CookiesMonster {
    fn new(i: int) -> CookiesMonster {
        CookiesMonster { cookies: i, hungry_level: i + 1 }
    }

    fn attack(&self) {
        println!("I have {:d} cookies!!", self.cookies)
    }
}

struct Dummy {
    count: int
}

impl Dummy {
    fn new(i: int) -> Dummy {
        Dummy { count: i }
    }
}

现在,这有效:

let monster: CookiesMonster = Monster::new(10);
let dummy …

以下代码应该读取文件并Item为每行创建记录:

defmodule Ship do
  defrecord Item, product_code: 0, quantity: 0, destination: ""

  def load_data do
    File.read!("data") 
      |> String.split 
      |> Enum.map &(String.split &1, ",")
      |> Enum.map &(list_to_item &1)
  end

defp list_to_item([pc, q, d | []]) do
    {parsed_q, _} = Integer.parse q
    Item.new product_code: pc, quantity: parsed_q, destination: d
  end
end

有一个data包含以下内容的文件:

1,100,London
1,30,Lisbon
3,2,Braga

问题是,当我执行load_data函数时,看起来最后一次调用Enum.map试图递归调用父函数(load_data)并抛出一个BadArityError.

输出如下:

iex(1)> Ship.load_data
** (BadArityError) #Function<0.127338698/1 in Ship.load_data/0> with arity 1 called with 2 arguments ({:cont, []}, #Function<30.103209896/2 in Enum.map/2>) …