thanks to mrgenixus

Getter Setter

(function(){ //don't work in the global scope

    var double = function(a){ return a * 2; }

    var process_validation = function(validation_params){

        if (validation_params) return function(val){
            // do magjiks
            if (validation_params.filter) val = val.match(validation_params.filter)[0]
            val = Math.round(val)
            if (validation_params.min) val = max(val,validation_params.min)
            if (validation_params.max) val = min(val,validation_params.max)
            return val;
        }

        return function(val){
            return val; //don't do any magic
        }
    }

    var getterSetter = function(validation_params){
        var _val = (validation_params && validation_params.defaultVal) || undefined;
        var process = process_validation(validation_params);
        return function(val){
            if (typeof val == 'function'){ val = val(_val) }
            val = process(val);
            return _val = val || _val;
        }
    }

})();

function StateObject() {}
var state = new StateObject();
StateObject.prototype.width = function(){return true}