The invoke op is bothering me -- namely, it disturbs me that it implicitly operates on P0. I know that P0 is the correct register to use according to pdd03, but I dislike having it be implicit. The user is required to set the rest of the pdd03 conventions up manually, so I don't see any need for invoke to be different. And it makes it much more clear what registers are being used if you have to pass in a PMC as an argument.
So would anyone mind if I eliminated the zero-arg invoke op in favor of a one-arg invoke that takes a single PMC? (I may also have situations where I don't need to follow pdd03, and it would be more convenient to use a different register.)
