Config variable inheritance: docs and rules

[Jonathan Matthews]

Hi all -

http://www.ruby-forum.com/topic/188742 seems to contain some
information I've not found explicitly stated anywhere else: that
config variable inheritance is an all or nothing mechanism. Have I
missed some docs somewhere?

Following on from this, I'd like to understand if there's anything I
can reliably determine from a variable's name about the impact that
defining it will have on *other* variables inheritance.

Can I, for instance, assume that defining an xyx_ prefixed variable in
a sub-scope will affect *only* the inheritance of other xyz_ prefixed
variables? Or can there be inheritance side-effects between, say $abc
and $def that I can't possibly determine without documentation or
trial and error?

Equally, can I assume that *all* xyz_ prefixed variables will have
their inheritance affected by the sub-scope definition of *any* other
xyz_ prefixed variable? Or are there examples where defining $xyz_foo
does *not* invalidate the inheritance of $xyz_bar ?

Thanks,
Jonathan
-- 
Jonathan Matthews
London, Oxford, UK
http://www.jpluscplusm.com/contact.html