gistfile1.hrl

% a_model.erl

-module(a_model).
-export([init/1,handle/2]).

-behaviour(model).


init({X,Y}) ->
    {ok,{X,Y}}.

handle(Self,get_x) -> 
    {X,_Y} = model:state(Self),
    {ok,X};

handle(Self,get_y) -> 
    {_X,Y} = model:state(Self),
    {ok,Y};

handle(Self,{set_x,NewX}) -> 
    {X,Y} = model:state(Self),
    {ok, X, {NewX, Y}};
    
handle(Self,{set_y,NewY}) -> 
    {X,Y} = model:state(Self),
    {ok, Y, {X, NewY}};

handle(Self, get_y_square) ->
    {_NewSelf, Y} = model:call(Self,get_y),
    {ok, Y*Y}.


% b_module.erl

-module(b_model).
-export([init/1,handle/2]).

-behaviour(model).


init({X,Y,Z}) ->
    {ok, Z, {a_model,{X,Y}}}.

handle(Self,get_z) -> 
    Z = model:state(Self),
    {ok,Z};

handle(Self,{set_z,NewZ}) -> 
    OldZ = model:state(Self),
    {ok, OldZ, NewZ};

handle(_Self,get_y) -> 
    {ok,1000}.

%Eshell V5.6.5  (abort with ^G)
%1> M  =model:new(b_model,{1,2,3}).
%{{b_model,3},{a_model,{1,2}}}
%2> {_,Res} =  model:call(M,get_x), Res.
%1
%3> {_,Res1} =  model:call(M,get_z), Res1.
%3
%4> {_,Res2} =  model:call(M,get_y_square), Res2.
%1000000
%5>