Martin Maechler wrote: >>>>>> "PD" == Peter Dalgaard <[EMAIL PROTECTED]> >>>>>> on Tue, 18 Nov 2008 00:00:40 +0100 writes: > > PD> Martin Maechler wrote: > >> But in spite of all that I agree that I'd have liked > >> `FALSE` <- <whatever> to signal an error about the fact > >> that it is a reserved word. > >> > RT> This is clearly not a very important issue, but it might > RT> bear some thinking about. > >> > >> Yes. I'd propose that R-core look into how to make > >> assignment to a reserved word an error. > > PD> I disagree. In a sense, this is the point of having the > PD> backtick operator: allowing you to work with names that > PD> would otherwise be syntax errors (notice that such names > PD> are sometimes created outside your control, e.g. via > PD> column names in data frames). If you start disallowing > PD> some of them again, well, that way lies madness! > > No, no. I'm not against allowing names that are otherwise syntax > errors. They were always possible via assign(). > I just am convinced we should not allow reserved words.
Please unconvince yourself then... You are solving a problem that isn't there: In R, you can assign to `FALSE` and access it as `FALSE`. You can not access it as FALSE because that is a keyword and you cannot assign to FALSE either. > { S / S-plus does not either and gives a nice error message: > > S> assign("FALSE", TRUE) > Problem: The name "FALSE" is reserved -- assignments to it are not allowed > } But FALSE is not a keyword in S. In R this would correspond to locking down F and T. There's another issue, namely that some keywords do have associated functions; e.g., `if` exists as a variable, and walls do come tumbling down if you redefine it (to a different function). However, that is a completely different thing, more related to redefining "+". (Incidentally, how hard would it be to ensure that such symbols were always looked up in the base namespace?). -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel