Batch script for mass install of ports?

I was wondering if anyone has any experience writing batch scripts which can
install batches of Darwin (Mac) ports in sequence so that an admin doesn't
have to baby sit installation of many ports in a sequence-dependent chain of
ports?

Of course this would mean that some sort of exception handling would have to
be built in to the script such that if a port failed to build, it would then
stop and not continue to build ports that would be further dependent on the
broken port.

Surely dependent ports will be installed automatically by first installing a
port if its dependencies have not already been installed. However, I think
it would be nice to have each port installed one at a time for auditing
purposes. And let us not forget that dependency chains can be delicate and
if one link the chain breaks that could spell trouble for its dependents.

My first thought is that an expect script would be useful for this type of
task. I was thinking of writing one but I didn't want to re-invent the wheel
if someone has already put together something like this.

Also, has anyone ever written an application that can read an installed
dependency chain of ports and visualize them with graphs? That would be
really cool to have a visual tool.

Best regards,

T.