I would look at the problem differently.

• What system are you trying to model?
• What are the things that do stuff in that system?
• What is the minimal set of actions that each thing needs to be able to do?
• How will those things interact?

Once you know those things, then you can start working out what attributes each class needs to have in order to fulfill its requirements. Then, and only then, can you figure out where that information needs to come from. You may find out that most of it shouldn't come from the client at all!

Now, to answer the question "How do I pass attribute/value pairs to a constructor?" ... your very short constructor is actually the canonical (if non-resilient) way of doing it. *shrugs* Personally, I'd never use that outside of golf, but that's just me. There's CPAN code you use every day that uses that (or similarly terse) constructs. Heck, CGI doesn't even use strict!