我正在尝试使用进程创建一个二叉树。

-module(binarytree).

-export([start/1, loop/2]).

start(N) ->
    P = spawn(?MODULE, loop, [N, self(), self(), self()]),
    P ! create_nodes,
    receive
    end.

loop(0, _, _, _) ->
    done;

loop(N, Root, LeftNode, RightNode) ->
    receive
        create_nodes ->
            MyPid = self(),
            LeftNode = spawn(?MODULE, loop, [N-1, MyPid, ???, ???]),
            RightNode = spawn(?MODULE, loop, [N-1, MyPid, ???, ???]),
            LeftNode ! create_nodes,
            RightNode ! create_nodes;
        _ ->
            ok
    end,
    loop(N, Root, LeftNode, RightNode).

如果没有LeftNode和RightNode，我可以成功地创建树结构，但是我想在循环状态中保存LeftNode和RightNode。在创建节点时，我应该在函数参数中传递什么？

• • 更新：感谢Nalin Ranjan。**更改这些行：

MyPid = self(),
LeftNode = spawn(?MODULE, loop, [N-1, MyPid, ???, ???]),
RightNode = spawn(?MODULE, loop, [N-1, MyPid, ???, ???]),
LeftNode ! create_nodes,
RightNode ! create_nodes;

收件人：

MyPid = self(),
NewLeftNode = spawn(?MODULE, loop, [N-1, MyPid, "", ""]),
NewRightNode = spawn(?MODULE, loop, [N-1, MyPid, "", ""]),
NewLeftNode ! create_nodes,
NewRightNode ! create_nodes,
loop(N, Root, NewLeftNode, NewRightNode);