As any of you who looked at the syntax may have noticed, the current syntax is a bit evil since you write

IMP_BEGIN_CHECK(EXPENSIVE); some stuff which gets controlled by the surrounding statement and is in a nested scope IMP_END_CHECK;

We want something that naturally conveys that the surrounded blocks are in a nested scope.

One possibility is something like

IMP_IF_CHECK(level) which would expand to if (get_check_level() > level)

So the user has to add braces to put more than one statement in there. I think I like that better and emacs does the right thing with indenting it. Any thoughts?