Accessors in Javascript

Here's an example of javascript metaprogramming and creating accessor methods for javascript properties:

  
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File:  accessors.js
 Based on an idea from William Tayson ( http://www.jadetower.org ):
 "Bringing method_missing to javascript" -- 
 http://www.jadetower.org/muses/archives/000388.html

 To create a "mixin" for accessor methods.

 Part of the Tarpaulin Project

 http://tarpaulin.rubyforge.org

 Written by ottercat -- ottercat@ottercat.net

 No dependencies on other code 
 Copyright (c) 2006 by Matt Williams, aka Ottercat

License:
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
 without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
 permit persons to whom the Software is furnished to do so, subject to
 the following conditions:
 
 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

/*
   Function: accessorWrapper
   Wrapper function for the accessors.  It does the work of both the "getter" and "setter"
   functions.

   Parameters:

      method - a string representation of the method name, i.e., getX or setX

   Returns:
  
      A pointer to the accesor function
*/
function accessorWrapper(method){
    return function(arg) {
       var property=method.substr(3,1).toLowerCase()+method.substr(4);
  var mode=method.substr(0,3);
  if(mode == "get")
    {
        return this[property];
    }
  else
    {
        this[property]=arg;
    }
    }
}


/*
  Class: Accessors

  Parameters:

     properties - a whitespace delimited string of properties

  Returns:

     An object consisting of functions which are accessors for the specified properties.
     <accessorWrapper> is invoked for each property to create its accessors.

  See Also:
 
   <accessorWrapper>

*/

function Accessors(properties) {
    properties=properties.split(/[ \t\n]+/);
    for (var i=0; i < properties.length; i++)
      {
    this[properties[i]]="";
    getter="get"+properties[i].substr(0,1).toUpperCase()+properties[i].substr(1);
    this[getter]=accessorWrapper(getter);
    setter="set"+properties[i].substr(0,1).toUpperCase()+properties[i].substr(1);
    this[setter]=accessorWrapper(setter);
      }

}

/*
  Function: attrReader
     Follow the Ruby convention here of creating a reader

  Parameters:

    attributes - a whitespace delimited list of attributes for which you wish to create a Ruby-like reader

  Returns:

   an object containing accessor functions in the manner of getX where x are the attributes
*/
function attrReader(attributes) {
    properties=properties.split(/[ \t\n]+/);
    for (var i=0; i < attributes.length; i++)
      {
    if(this[attributes[i]] == undefined)
      {
    this[attributes[i]]="";
      }
    getter="get"+attributes[i].substr(0,1).toUpperCase()+attributes[i].substr(1);
    this[getter]=accessorWrapper(getter);
      }
}



/*
  Function: attrWriter
     Follow the Ruby convention of creating a writer

  Parameters:

    attributes - a whitespace delimited list of attributes for which you wish to create a Ruby-like writer

  Returns:

   an object containing accessor functions in the manner of setX where x are the attributes
*/
function attrWriter(attributes) {
    properties=properties.split(/[ \t\n]+/);
    for (var i=0; i < attributes.length; i++)
      {
    if(this[attributes[i]] == undefined)
      {
    this[attributes[i]]="";
      }
    setter="set"+attributes[i].substr(0,1).toUpperCase()+attributes[i].substr(1);
    this[setter]=accessorWrapper(setter);
      }
}