-module(link_demo).
-export([start/0, demo/0, demonstrate_normal/0, demonstrate_exit/1,
         demonstrate_error/0, demonstrate_message/1]).

start() ->
    register(demo, spawn(link_demo, demo, [])).

demo() ->
    process_flag(trap_exit, true),
    demo1().

demo1() ->
    receive
         {'EXIT', From, normal} ->
             io:format(
                 "Demo process received normal exit from ~w~n",
                 [From]),
             demo1();
         {'EXIT', From, Reason} ->
             io:format(
                 "Demo process received exit signal ~w from ~w~n",
                 [Reason, From]),
             demo1();
         finished_demo ->
             io:format("Demo finished ~n", []);
         Other ->
             io:format("Demo process message ~w~n", [Other]),
             demo1()
    end.

demonstrate_normal() ->
    link(whereis(demo)).

demonstrate_exit(What) ->
    link(whereis(demo)),
    exit(What).

demonstrate_message(What) ->
    demo ! What.

demonstrate_error() ->
    link(whereis(demo)),
    1 = 2.