Question: My googlefu sucks and was unable to find information on this.

Basically I want to have a instance variable that is visible only within the scope of a class/module but is also immutable.

I am new to Ruby and apologize if this question doesn't make much sense.

Answer: 
Ruby constants aren't very constant: they're not immutable, and you can assign another value to them and all you get is a warning. See the question [Constant Assigment Bug in Ruby?](https://stackoverflow.com/questions/3010768/constant-assigment-bug-in-ruby)
I wrote a gem for this case.
<http://rubygems.org/gems/instancevalue>

(The approaching as Ken's one.)