sandbox/pe/chapter12.erl

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751 B
Erlang
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-module(chapter12).
-compile(exportall).
-export([start/2, registrar/0]).
registrar(Client, {Name, Fun}) ->
case whereis(Name) of
undefined ->
Pid = spawn(Fun),
register(Name, Pid),
Client ! {ok, Name, Pid};
Pid -> Client ! {error, exists, Pid}
end.
registrar() ->
receive
{Client, {Name, Fun}} ->
registrar(Client, {Name, Fun}),
registrar();
X -> io:format("Spurious message ~w received~n", [X])
end.
start(AnAtom, Fun) ->
%% start the registrar if it's not been started.
case whereis(registrar_proc) of
undefined ->
Pid = spawn(chapter12, registrar, []),
register(registrar_proc, Pid);
_ -> void
end,
registrar_proc ! {self(), {AnAtom, Fun}},
receive X -> X end.