> > No! 'identifier?' does not check whether a syntax object represents a > variable reference, given 1) identifier macros and 2) #%top transformers for > unbound variables. If you really, really want to check if something is a > variable reference, 'local-expand' it and look at the result. >
Will I not always get an "unbound identifier in module" (or something similar) with the offending variable explicitly in the message? That's as good to me as any message I make up. If not, it would be worth the effort. > But even if it is a variable reference, there's no guarantee that there > isn't another thread holding a reference to it, waiting to change it from a > real to, say a complex number right after the 'real?' check is done. > I'm sure one can always come up with pathological things that can be done. Even if I do something to ensure that the test and binding are atomic, I not sure it doesn't defeat the purpose of the macro - to protect unsafe code. I would say don't use unsafe code on variables that are shared among processes. But thanks for the comments. > > Ryan > >
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