class property not updating value if 'self' keyword is not used

[Ryan McCullagh]

class Buffer
{
	function Buffer(value)
	{
		self.stream   = value;
		self.position = 0;
	}

	function advance()
	{
		return stream[position++];
	}

	function top()
	{
		return stream[position];
	}
}

buffer = Buffer("Hello World");
buffer.advance();
if(buffer.position == 0)
{
  throw "Expected buffer.position to be greater than 0";
}