Can not find superclass

I defined two classes 'Super' und 'Sub' in two separate files
that look
like this:

class Super < ActiveRecord::Base
end

class Sub < Super
end

After compiling 'Sub' I get the following error message
"uninitialized
constant Super (NameError)"

I believe your problem is that, for each request, rails only loads the
appropriate controller files. You need to put a 'require' or 'load' (or
some rails-specific require command) in your second file to ensure that
the controller file that you define Super in is being loaded (causing
Super to be defined) before you attempt to use it.