From: Devin Mullins <twifkak@...>
Date: 2006-11-05T04:02:55+09:00
Subject: Re: Redefining a class

$ ri remove_const
---------------------------------------------------- Module#remove_const
      remove_const(sym)   => obj
------------------------------------------------------------------------
      Removes the definition of the given constant, returning that
      constant's value. Predefined classes and singleton objects (such as
      _true_) cannot be removed.

For a more thorough answer, read the Rails reloading code.

Devin