test.js

new function(_) { // create the closure
  // create the package object
  var shapes = new base2.Package(this, {
    name:    "shapes",
    version: "1.0",
    exports: "PI,Circle,Rectangle"
  });
  
  // evaluate the imported namespace
  eval(this.imports); 
  
  var PI = 3.14;
  
  var Shape = Base.extend({
    consructor: function(x, y) {
      this.move(x, y);
    },
    x: 0,
    y: 0,
    getArea: Undefined,
    move: function(x, y) {
      this.x = Number(x);
      this.y = Number(y);
    }
  });
  
  var Circle = Shape.extend({
    consructor: function(x, y, radius) {
      this.base(x, y);
      this.radius = Number(radius);
    },
    radius: 0,
    getArea: function() {
      return PI * Math.pow(this.radius, 2);
    }
  });
  
  var Rectangle = Shape.extend({
    consructor: function(x, y, width, height) {
      this.base(x, y);
      this.width = Number(width);
      this.height = Number(height);
    },
    width: 0,
    height: 0,
    getArea: function() {
      return this.width * this.height;
    }
  });
  
  // evaluate the exported namespace (this initialises the Package)
  eval(this.exports);
}

eval(base2.shapes.namespace);

var circle = new Circle( 5, 5, 10 );
console.log( circle.getArea() );