Thanks for all the responses.  For efficiency purposes (because the file
is accessed so often), probably I prefer 2) rather than 3).  Depending on
the implementation, I guess, 1) will be somewhere between 2) and 3).

However, this is only for the one specific example.  I guess, then, indeed
there is no way to emulate pointer in Ruby.  I used Perl not for long
before I switched to Ruby.  If I am not mistaken, in Perl there is stuff
called reference.

Regards,

Bill
========================================================================
> Some other options:
>   1) Use a delegator.  A SimpleDelegator can change the object it is
>      delegating to on-the-fly.  The children get a reference to the
>      delegator instead of to the IO object you are using.
>   2) Use the observer pattern.  Whenever you change which file you are
>      accessing, mark your state as changed and notify your observers
>      that they need to refetch their references.
>   3) Use ts's suggestion of always accessing the file object via an
>      accessor in the root object.

> Paul