Lisp programmers often use the REPL (similar to IRB) as a simple way
to make an interactive interface to their app.  I'd like to do the
same thing with irb - that is, define my classes, and load irb in the
context.

I can get about half way there:

 require 'irb'
 IRB.start
 my_class = MyClass.new(...) # I want this to be the context
 irb my_class

...works, but you have to type "quit" to load.  Is there a better way
to leverage IRB from within my code?  What do the Ruby hackers say? (I
know a lot have a Lisp background, and so wouldn't want Ruby to not
have a REPL shell...)