Erlang and process_flag(trap_exit, true)

Question

After watching the Pragmatic Studio screen casts on Erlang, the last video on Supervisors mentioned that in order for a supervisor to get a notification about one of its chi

Answer 1

You have 3 idioms:

1/ I don't care if my child process dies:

spawn(...)

2/ I want to crash if my child process crashes:

spawn_link(...)

3/ I want to receive a message if my child process terminates (normally or not):

process_flag(trap_exit, true),
spawn_link(...)

Please see this example and try different values (inverse with 2 or 0 to provoke an exception, and using trap_exit or not):

-module(play).
-compile(export_all).

start() ->
    process_flag(trap_exit, true),
    spawn_link(?MODULE, inverse, [2]),
    loop().

loop() ->
    receive
        Msg -> io:format("~p~n", [Msg])
    end,
    loop().

inverse(N) -> 1/N.