Deserialized gen_server pattern

deser_gs.erl

-module(deser_gs).

-export([start_link/0]).

-export([init/1, handle_call/3, terminate/2]).

-export([hello/2, handle_hello/3]).
-export([world/1, handle_world/3]).


start_link() ->
  gen_server:start_link(?MODULE, none, []).


init(none) ->
  {ok, #{}}.


%% Generic call. API function provides a handler.
deser_call(Server, Function, Arg) ->
  gen_server:call(Server, {'$deser_rpc', Function, Arg}).

handle_call({'$deser_rpc', Function, Arg}, From, State) ->
  ?MODULE:Function(Arg, From, State).

terminate(_, _) ->
  ok.



hello(Server, Who) ->
  deser_call(Server, handle_hello, Who).

handle_hello(Who, _From, #{} = State) ->
  {reply, {hello, Who}, State#{hello => Who}}.


world(Server) ->
  deser_call(Server, handle_world, none).

handle_world(none, _From, #{hello := Who} = State) ->
  {reply, {Who, nearby}, State};
handle_world(none, _From, #{} = State) ->
  {reply, i_am_so_lonely, State}.