ruby_scoping.js

// Provides Ruby-style scoping to JS.Class, whereby constants
// and nested classes are accessible as 'this.FOO' within class
// and instance methods, removing the need for extend() blocks
// and 'this.klass.FOO' references.

JS.RubyScoping = new JS.Module({
  extend: {
    included: function(base) {
      // Store constants in a separate module, and have
      // base inherit its constants from this
      base.__consts__ = new JS.Module();
      base.extend(this.ClassMethods);
      base.include(base.__consts__);
      base.extend(base.__consts__);
    },
    
    // Methods to extract constants into __consts__ module
    ClassMethods: new JS.Module({
      extend: function() {
        this.__consts__.include(JS.RubyScoping.gather(arguments[0], this));
        this.callSuper();
      },
      
      include: function() {
        this.__consts__.include(JS.RubyScoping.gather(arguments[0], this));
        this.callSuper();
      }
    }),
    
    // Extract constants from an object
    gather: function(inclusions, base) {
      if (!inclusions) return null;
      if (inclusions.isA && inclusions.isA(JS.Module)) return null;
      var constants = {}, key, object;
      for (key in inclusions) {
        
        // Constants must begin with a capital letter
        if (!/^[A-Z]/.test(key)) continue;
        
        // Move constant between objects
        object = inclusions[key];
        constants[key] = object;
        delete inclusions[key];
        
        // Allow nested modules/classes to inherit
        // constants from their containing modules
        if (object.isA && object.isA(JS.Module)) {
          object.include(this);
          object.include(base.__consts__);
          object.extend(base.__consts__);
        }
      }
      return constants;
    }
  }
});