wip

1 files changed, 84 insertions, 0 deletions

diff --git a/learn-you-some-erlang/musicians.erl b/learn-you-some-erlang/musicians.erl
new file mode 100644
index 0000000..e369d44
--- /dev/null
+++ b/learn-you-some-erlang/musicians.erl
@@ -0,0 +1,84 @@
+-module(musicians).
+-behaviour(gen_server).
+
+-export([start_link/2, stop/1]).
+-export([init/1, handle_call/3, handle_cast/2,
+         handle_info/2, code_change/3, terminate/2]).
+
+-record(state, {name="", role, skill=good}).
+-define(DELAY, 750).
+
+start_link(Role, Skill) ->
+    gen_server:start_link({local, Role}, ?MODULE, [Role, Skill], []).
+
+stop(Role) -> gen_server:call(Role, stop).
+
+init([Role, Skill]) ->
+    %% To know when the parent shuts down
+    process_flag(trap_exit, true),
+    %% sets a seed for random number generation for the life of the process
+    %% uses the current time to do it. Unique value guaranteed by now()
+    random:seed(now()),
+    TimeToPlay = random:uniform(3000),
+    Name = pick_name(),
+    StrRole = atom_to_list(Role),
+    io:format("Musician ~s, playing the ~s entered the room~n",
+              [Name, StrRole]),
+    {ok, #state{name=Name, role=StrRole, skill=Skill}, TimeToPlay}.
+
+handle_call(stop, _From, S=#state{}) ->
+    {stop, normal, ok, S};
+handle_call(_Message, _From, S) ->
+    {noreply, S, ?DELAY}.
+
+handle_cast(_Message, S) ->
+    {noreply, S, ?DELAY}.
+
+handle_info(timeout, S = #state{name=N, skill=good}) ->
+    io:format("~s produced sound!~n",[N]),
+    {noreply, S, ?DELAY};
+handle_info(timeout, S = #state{name=N, skill=bad}) ->
+    case random:uniform(5) of
+        1 ->
+            io:format("~s played a false note. Uh oh~n",[N]),
+            {stop, bad_note, S};
+        _ ->
+            io:format("~s produced sound!~n",[N]),
+            {noreply, S, ?DELAY}
+    end;
+handle_info(_Message, S) ->
+    {noreply, S, ?DELAY}.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+terminate(normal, S) ->
+    io:format("~s left the room (~s)~n",[S#state.name, S#state.role]);
+terminate(bad_note, S) ->
+    io:format("~s sucks! kicked that member out of the band! (~s)~n",
+              [S#state.name, S#state.role]);
+terminate(shutdown, S) ->
+    io:format("The manager is mad and fired the whole band! "
+              "~s just got back to playing in the subway~n",
+              [S#state.name]);
+terminate(_Reason, S) ->
+    io:format("~s has been kicked out (~s)~n", [S#state.name, S#state.role]).
+
+%% Yes, the names are based off the magic school bus characters
+%% 10 names!
+pick_name() ->
+    %% the seed must be set for the random functions. Use within the
+    %% process that started with init/1
+    lists:nth(random:uniform(10), firstnames())
+    ++ " " ++
+    lists:nth(random:uniform(10), lastnames()).
+
+firstnames() ->
+    ["Valerie", "Arnold", "Carlos", "Dorothy", "Keesha",
+     "Phoebe", "Ralphie", "Tim", "Wanda", "Janet"].
+
+lastnames() ->
+    ["Frizzle", "Perlstein", "Ramon", "Ann", "Franklin",
+     "Terese", "Tennelli", "Jamal", "Li", "Perlstein"].
+
+