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var test = function(name)
{
	this.name = name;

}

test.prototype= {

	setInitial:  function( b )
	{
		name=this.name;
		if (b)
		{
			 this.callback = {
			 //***************************************
			 initial: function(){return this.arg[0];},
			 //***************************************
			 arg: name
			 }
		}
		else
		{
			this.initial=name[0];
		}

	},
	getInitial:  function()
	{
		if (this.callback)
			return this.callback.initial(); 
		else
			return this.initial;
	}
}

r= new test('raphael');
c= new test('cathy');
r.setInitial(true);
c.setInitial();

Test it