gistfile1.txt

Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.6.5  (abort with ^G)
1> c("/Users/mark/Projects/erlang/excercises/parallel/ex3.erl", [{outdir, "/Users/mark/Projects/erlang/excercises/parallel"}]).
{ok,ex3}
2> ex3:start(foo, fun ex3:loop/0).
yes
3> ex3:start(foo, fun ex3:loop/0).
Function already registered.
ok
4> global:send(foo, { print, "whee!" }).
whee!
<0.37.0>
5> global:send(foo, { print, "whee!" }).
whee!
<0.37.0>
6> global:send(foo, exit).              
<0.37.0>
7> ex3:start(foo, fun ex3:loop/0).                                                                  yes                        
8> global:send(foo, { print, "alive again!" }).
alive again!
<0.43.0>

gistfile2.erl

-module(ex3).
-compile(export_all).

loop() ->
  receive
    {print, Msg} ->
      io:format("~s~n", [Msg]),
      loop();
    exit -> ok
  end.
  
start(AnAtom, Fun) ->
  global:trans({funLock, AnAtom}, fun() ->
                           case global:whereis_name(AnAtom) of
                             undefined ->
                               Pid = spawn(Fun),
                               global:register_name(AnAtom, Pid);
                             _ ->
                               io:format("Function already registered.~n")
                           end end).