dci2.js

Battle = Context(function(bearPlayer, lionPlayer){
    Bear = bearPlayer;
    Lion = lionPlayer;
    Bear.fight();
    Lion.touch();
    Lion.fight();
},{
  Lion : {
    fight : function(){
      console.log(this.name + " : meow");
    },
    touch : function(){
      Lion.fight();
      Bear.fight();
    }
  },
  Bear : {
    fight : function(){
      console.log(this.name + " : grrr");
    }
  }
});

var player = {name:"player"};
var cpu = {name:"cpu"};
var b = Battle(player, cpu);

function Context(init, roles) {
  // closure for scoping things
  var sfn = "(function(){\n";
  // scoped role players
  sfn += "  var " + Object.keys(roles).join(",") + ";\n";
  // creates the function
  var mkName = function(role, fn){ return role + "$" + fn; };  
  // redirects all role method calls
  var fixMethod = function(fn){
    fn = fn.toString();
    for(var roleName in roles){
      var role = roles[roleName];
      for(var fnName in role){
        // replaces Role.method(arg1,arg2,arg3) with
        //     with Role$method.call(Role, arg1, arg2, arg3)
        var rx = new RegExp( "([^.])" + roleName + "\\." + fnName + "\\(", "g");
        fn = fn.replace(rx,  "$1" + mkName(roleName, fnName) + ".call(" + roleName + ",");
        // hack-fix Role$method.call(Arg,)
        fn = fn.replace(",)", ")");
      }
    }
    return fn;
  };
  // define role methods in to the context
  var methods = [];
  for(var roleName in roles){
    var role = roles[roleName];
    for(var fnName in role){
      methods.push(mkName(roleName, fnName) + " = " + fixMethod(role[fnName]));
    }
  }
  sfn += "var " + methods.join(",\n") + ";\n";
  // return the init
  sfn += "return " + fixMethod(init) + ";})()";
  return eval(sfn);
}