Re: possible strange idea about hierarchical lists

[Ted Zlatanov <tzz@northernlight.com>]

prj@po.cwru.edu (Paul Jarc) writes:

> Ted Zlatanov <tzz@northernlight.com> wrote:
>> Parsing of the hierarchy specification.  It's a tree structure, with
>> the widest-coverage lists at the top and more specific lists at the
>> bottom.  I suppose it could be hacked as a 2-level list, but a tree
>> hierarchy is more generic.
>
> The 2-level list is just as expressive, I think, and easier to
> implement.  Suppose A contains B, and B contains C, and you have a
> message addressed to B and C.  In order to strip out C, you'd have to
> traverse the entire tree to first find B; there's no guarantee that
> the top level will have anything interesting.
>
> Also suppose A nd D both contain B.  This is actually easier to
> express with the 2-level list; with a tree, you'd have to duplicate
> the whole subtree under B.  With a 2-level list, you just add B under
> both A and D, and the code takes care of looking for a top-level B
> with its own entries under it.

You are right.  It's faster and easier (for implementer and user) to
use a 2-level list.  But is anyone except me interested in it?

Ted