Date: 06/01/06 (Javascript Community)    Keywords: html, java

I got tired of creating accessor methods for properties (as well as the properties themselves!) in my javascript classes, so, taking a note from the prototype.js library, I wrote a helper which acts a little like ruby's attr_writer and attr_reader as well as method_missing. It's loosely based upon a MockObject class written by William Tayson at http://www.jadetower.org/muses/archives/000388.html. The library itself does not have any dependencies, although I am (for convenience sake) using it with the prototype.js Object.extend() function in the example which follows. // Accessors
// 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
//
// tarpaulin.rubyforge.org
//
// Written by ottercat -- ottercat@ottercat.net
//
// No dependencies on other code

// a helper function used below by multiple functions/objects
function accessorWrapper(method){
    return function(arg) {
    var property=method.substr(3);
    var mode=method.substr(0,3);
    if(mode == "get")
      {
          return this[property];
      }
    else
      {
          this[property]=arg;
      }
    }
}


// create both a getX() and setX()
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);
      }

}

// follow the ruby convention here of creating a reader

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);
      }
}

// follow the ruby convention here of creating a writer

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);
      }
}
Here's test code, showing usage..... var test={
  fred : "flintstone",
  tom : "jerry",
  foo : function() { alert("test!");}
};

Object.extend(test,new Accessors("name rank"));
test.setName("Barney Fife");
test.setRank("Deputy");
for (i in test)
{
document.write(i + "
");
}
document.write(test.getName()+"
");
document.write(test.getRank()+"
");
I'll have this shortly posted to CVS, but what do you think?

Source: http://community.livejournal.com/javascript/101086.html