-module(town).
-behaviour(gen_server).-export([start/0, combine/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,code_change/3]).
-record(state, {port}).start() ->gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).stop() ->gen_server:cast(?MODULE, stop).init([]) ->process_flag(trap_exit, true),Port = open_port({spawn,"python -u ./town.py"},[stream, {line, 1024}]),{ok, #state{port = Port}}.handle_call({combine, Str}, _From, #state{port = Port} = State) ->io:format("here~n"),port_command(Port, Str),receive{Port, {data, {_Flag, Data}}} ->io:format("receiving:~p~n", [Data]),timer:sleep(2000),{reply, Data, Port}end.handle_cast(stop, State) ->{stop, normal, State};
handle_cast(_Msg, State) ->{noreply, State}.handle_info(Info, State) ->{noreply, State}.terminate(_Reason, Port) ->ok.code_change(_OldVsn, State, _Extra) ->{ok, State}.% Internal
combine(_String) ->start(),Str = list_to_binary("combine|" ++ _String ++ "\n"),gen_server:call(?MODULE, {combine, Str}).

#! /usr/bin/python
# Filename : town.pyimport sysdef handle(_string):if _string.startswith("combine|"):string = "".join(_string[8:].split(","))return string""" waiting for input"""
while 1:# Recv.Binary Stream as Standard IN_stream = sys.stdin.readline()if not _stream:breakinString = _stream.strip("\r\n")outString = handle(inString)sys.stdout.write("%s\n" % (outString,))sys.exit(0)

Eshell V6.2  (abort with ^G)
1> town:combine("aaa+bbb").
here
receiving:"aaa+bbb"
"aaa+bbb"
2>