%%% Switch debugging output on/off:
%-define(DBG(Str, Args), ok).
-define(DBG(Str, Args), io:format(Str, Args)).

?DBG("Function fun1 starting... ~n", [])

?debugMsg("Function fun1 starting...")

?debugFmt("Function fun1 starting...", [])

-include_lib("eunit/include/eunit.hrl").

%% If compiled with {d, TEST, true}
%% This happens automatically during `rebar3 eunit`
-ifdef(TEST).
-define(TRACE(Template, Args), io:format(user, "TRACE ~p:~p ~p~n", [?MODULE, ?LINE, lists:flatten(Args)])).
-else.
-define(TRACE(_T, _A), void).
-endif.

-module(foo).
-export([ api/1 ]).

-include("trace.hrl").

api(Arg) ->
    ?TRACE("Called with Arg ~p~n", [Arg]),
    ok.