I’d be interested to know if anybody is using this too.
Might design-by-contract be a worthy addition to (perhaps my
implementation!) standard language?
I think so, despite the fact that I haven’t used it much myself 
My point is that DBC is actually more useful outside of the static
type checking environment of an Eiffel, C++, or Java. I truly do not
care about the type of an object I’m calling, but I care deeply about
it’s semantics, and that’s what Design by Contract is all about.
So yes, my two cents says it is a worthy element that can be used
effectively in the construction of larger systems. To be effective,
it should be part of the base-level language, and all of the standard
library classes should be annotated with contracts.
Ruby may never need it, but I don’t think we’ll know either way
unless the facility exists in such an ingrained manner that it
becomes second-nature to use it.
/\ndy