Every once in a while, someone emails me about Stringbean and wonders why I'm not working on it much. Stringbean is more like an LPMud than a MOO and would allow for in-game coding of objects in Python. I've been giving a few reasons of why I'm not really actively working on it:
It's not currently possible (without a lot of work) to build a restricted execution environment within the Python interpreter to protect the driver from the mudlib codebase if both are implemented in Python. That's not a wildly large issue except that it forces you to really trust in-game developers. The Zope folks have something like this in place, but I don't know if it would help me solve my problem or not. Mostly this requires a lot of research and work.
It's difficult to terminate infinite loops and other long-running code which will cause mudlag. It's not uncommon for me to accidentally create an infinite loop. If you can't somehow halt execution, then this forces you to shut down the whole mud and restart it. When working on Varium, we created a reaper thread which would send a signal to the Python process causing the execution thread (which was the main thread of execution) to throw an exception and thus "terminate" execution. Even with this, it's not clear what state the driver would be in. This also requires a lot more research and work.
I bumped into Twisted Reality (which is what this post is all about).
Twisted Reality is a MOO oriented mud so it's got a different focus than Stringbean does. However, Twisted Reality is also attempting to solve another big problem I have with muds using Aspects.
The problem is this: you build a bunch of objects the player can manipulate (things like torches, swords, hammers, nails, screwdrivers, etc) and in order to add another way for the players to manipulate and modify these objects, you have to code manipulation/modification-handling code for every single object. What if you wanted to allow players to burn an object? Well, for every object, you'd have to implement burn-handling code.
You could implement this using multiple inheritance. Each object inherits from a object-type class (armor, weapon, container, etc) as well as a material class (iron, wood, organic, copper, glass, etc). The material classes could handle effects like burning. But what if you had something like an axe with a wooden handle and an iron blade?
Anyhow, it'd be easier if the burn code could be centralized into one place--an aspect. The stuff in the Reality mailing list is interesting enough that even though I haven't looked into it further, it's caused me to want to wait to research it more before I go work on Stringbean again.