example.erl

-module(example).

-behaviour(gen_server).

%% API
-export([start_link/0]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).
-export([set_coordinates/2, get_coordinates/1]).


start_link() ->
    gen_server:start_link(?MODULE, [], []).

set_coordinates(Pid, XY = {X, Y}) when is_integer(X), is_integer(Y) ->
    gen_server:cast(Pid, {set_coors, XY}),
    ok.

get_coordinates(Pid) ->
    gen_server:call(Pid, get_coors).


init([]) ->
    {ok, {0,0}}.

handle_call(get_coors, _From, Position) ->
    {reply, Position, Position}.

handle_cast({set_coors, NewPosition}, _Position) ->
    {noreply, NewPosition}.

handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.