Yeah, definitely. But, this specific problem is in the context of writing a restricted eval, like for a browser plugin or something like that. I was thinking of doing a global replace of set with tempset and then cleaning up after one plugin runs. But maybe that is the wrong way to do it.
If you did this for all local variables, and then used namespace-undefine-variable! to delete any defs that had been evaluated, I think you would get a fairly well restricted eval.
I agree with you - I think this is roughly the right idea, I just hadn't found namespace-undefine-variable! when I asked this question.
I think there's still somewhat of a problem with wrapping variables in a "let" with their deep copies - that prevents internal code from wrapping builtins and having other builtins use the wrap, because the let will make the builtin-wrap scope different from the outer scope. But you can do the special-suffix thing in this case.
