Printing 为什么我会收到两次相同的信息?

Printing 为什么我会收到两次相同的信息?,printing,erlang,otp,gen-server,Printing,Erlang,Otp,Gen Server,我是Erlang的新手,我正在开发一个小程序来模拟收集罐头的机器人: -export([start/0]). start()-> Believes=#{bin_position=>0, num_cans=>1, can_position=>4, my_position=>1}, PID=spawn(fun()-> believes(Believes) end), action(PID,Believes). believes(NewB

我是Erlang的新手,我正在开发一个小程序来模拟收集罐头的机器人:

-export([start/0]).

start()->
    Believes=#{bin_position=>0, num_cans=>1, can_position=>4, my_position=>1},
    PID=spawn(fun()-> believes(Believes) end),
    action(PID,Believes).

believes(NewBelieves)->

    receive
        {add,Key,Value}->
            N1=maps:put(Key,Value,NewBelieves),
            print(N1),
            action(self(),N1),
            believes(N1);
        {remove, Key}->
            N2=maps:remove(Key, NewBelieves),
            print(N2),
            action(self(),N2),
            believes(N2);
        {update, Key, Value}->
            N3=NewBelieves#{Key => Value},
            print(N3),
            action(self(),N3),
            believes(N3);
        {get}->
            action(self(),NewBelieves),
            believes(NewBelieves)
    end.

print(Map)->
    List=maps:to_list(Map),
    io:format("Believes: ~p~n",[List]).

action(PID, Map)->
    case {is_holding(Map),is_over_bin(PID,Map)} of
            {false,false}->
                %io:format("Is not holding and is not over the bin ~n"),
                %timer:sleep(1000),
                case is_over_can(PID,Map) of
                    false->move(PID,right,Map);
                          % timer:sleep(1000);
                    _->hold(PID)
                       %timer:sleep(1000)
               end;
            {_,false}->
                %io:format("Is holding but is not over the bin ~n"),
                %timer:sleep(1000),
                move(PID, left, Map);
                %timer:sleep(1000);
            {_,_}->
                %io:format("Is holding and is over the bin ~n"),
                %timer:sleep(1000),
                drop(PID),
                timer:sleep(10000),
                exit(self(),kill)
        end.

is_over_can(PID, Map)->
    case same_position(maps:find(my_position,Map),maps:find(can_position, Map)) of
        equal->hold(PID);
        _->false
    end.

is_over_bin(PID, Map)->
    case same_position(maps:find(my_position,Map),maps:find(bin_position, Map)) of
        equal->drop(PID);
        _->false
    end.

is_holding(Map)->
    maps:is_key(holding,Map).

%is_gripper_on(Map)->
%   map:is_key(gripper_on,Map).
%is_touching(Map)->
%   map:is_key(touching,Map).

same_position({ok,A},{ok,B}) when A=:=B -> equal;
same_position(_, _) -> not_equal.

move(PID, Dir, Map)->
    {ok,MyPosition}=maps:find(my_position,Map),
    case Dir of
        right->PID ! {update, my_position, MyPosition+1};
        left->PID ! {update, my_position, MyPosition-1}
    end.  

hold(PID)->
    PID ! {add, holding, []},
    PID ! {update, can_position, nil}.

drop(PID)->
    PID ! {remove, holding},
    PID ! {update, num_cans, 0},
    PID ! {add, cans_collected, 1},
    timer:sleep(10000),
    io:format("Todas las latas han sido recogidas.~n"),
    timer:sleep(10000),
    exit(PID,kill).
当我运行代码时,在某些情况下,我会得到两次打印,但我不会从drop函数中得到最后3次打印:

普鲁巴2:开始

相信:[{bin_position,0},{can_position,4},{my_position,2},{num_cans,1}]

相信: [{bin_position,0},{can_position,4},{my_position,3},{num_cans,1}]

{更新,我的位置,2}

相信: [{bin_position,0},{can_position,4},{my_position,4},{num_cans,1}]

Prueba@Usuario2> 相信:[{bin_位置,0}, {can_位置,4}, {控股,[]}, {我的位置,4}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,4}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,4}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,4}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,3}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,3}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,3}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,3}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,2}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,2}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,2}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,2}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,1}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,1}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,1}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,1}, {num_cans,1}]

相信:[{bin_位置,0}, {can_position,nil}, {控股,[]}, {我的位置,0}, {num_cans,1}]

这是我的荣幸

我做错什么了吗?它是否与每个流程需要执行的时间有关?我也不知道是否有办法用OTP实现它,我的意思是,使用gen_服务器或其他什么

非常感谢你

尝试运行以下代码:

-module(so1).
-export([start/0]).

start()->
    Believes = #{bin_position=>0, num_cans=>1, can_position=>4, my_position=>1},
    PID = spawn(fun()-> believes(Believes) end),
    action(PID,Believes).

believes(NewBelieves)->

    receive
        {add,Key,Value}->
            N1=maps:put(Key,Value,NewBelieves),
            io:format("add clause:~n"),
            print(N1),
            action(self(),N1),
            believes(N1);
        {remove, Key}->
            N2=maps:remove(Key, NewBelieves),
            io:format("remove clause:~n"),
            print(N2),
            action(self(),N2),
            believes(N2);
        {update, Key, Value}->
            N3=NewBelieves#{Key => Value},
            io:format("update clause:~n"),
            print(N3),
            action(self(),N3),
            believes(N3);
        {get}->
            action(self(),NewBelieves),
            believes(NewBelieves)
    end.

print(Map)->
    List=maps:to_list(Map),
    io:format("Believes: ~p~n",[List]).

action(PID, Map)->
    case {is_holding(Map),is_over_bin(PID,Map)} of
            {false,false}->
                %io:format("Is not holding and is not over the bin ~n"),
                %timer:sleep(1000),
                case is_over_can(PID,Map) of
                    false->
                        io:format("action() is calling move()~n"),
                        move(PID,right,Map);
                          % timer:sleep(1000);
                    _->hold(PID)
                       %timer:sleep(1000)
               end;
            {_,false}->
                %io:format("Is holding but is not over the bin ~n"),
                %timer:sleep(1000),
                move(PID, left, Map);
                %timer:sleep(1000);
            {_,_}->
                %io:format("Is holding and is over the bin ~n"),
                %timer:sleep(1000),
                drop(PID),
                timer:sleep(10000),
                exit(self(),kill)
        end.

is_over_can(PID, Map)->
    case same_position(maps:find(my_position,Map),maps:find(can_position, Map)) of
        equal->hold(PID);
        _->false
    end.

is_over_bin(PID, Map)->
    case same_position(maps:find(my_position,Map),maps:find(bin_position, Map)) of
        equal->drop(PID);
        _->false
    end.

is_holding(Map)->
    maps:is_key(holding,Map).

%is_gripper_on(Map)->
%   map:is_key(gripper_on,Map).
%is_touching(Map)->
%   map:is_key(touching,Map).

same_position({ok,A},{ok,B}) when A=:=B -> equal;
same_position(_, _) -> not_equal.

move(PID, Dir, Map)->
    {ok,MyPosition}=maps:find(my_position,Map),
    io:format("move() is going to send update message~n"),
    case Dir of
        right-> PID ! {update, my_position, MyPosition+1};
        left -> PID ! {update, my_position, MyPosition-1}
    end.  

hold(PID)->
    io:format("hold() is sending add, update messages,~n"),
    io:format("which will result in two prints:~n"),
    PID ! {add, holding, []},
    PID ! {update, can_position, nil}.

drop(PID)->
    io:format("drop() is sending remove, update, add messages,~n"),
    io:format("which will result in three prints:~n"),
    PID ! {remove, holding},
    PID ! {update, num_cans, 0},
    PID ! {add, cans_collected, 1},
    timer:sleep(10000),
    io:format("Todas las latas han sido recogidas.~n"),
    timer:sleep(10000),
    exit(PID,kill).
输出将显示您的代码是一团混乱。此外,当您创建多个进程时,输出可以交错并以与写入不同的顺序出现

我对二郎很陌生

您只能编写调试技能所能处理的程序。现在坚持20行或更少。您可能还想尝试使用单步执行代码

我也不知道有没有办法用OTP来实现, 使用gen_服务器或其他东西


任何带有receive子句和保存状态的循环变量的无限循环都可以被视为服务器,因此可以实现为gen_服务器。

这里的预期输出是什么?请通过删除不相关的代码创建一个最小的示例,很难理解这段代码到底在做什么。我应该只收到一条信息。我用gen_服务器行为解决了这个问题,一旦你知道如何使用它,它就棒极了!谢谢你的回答:D。