Greetings everyone, I have a question about the default behaviour of a missing entry in an environment. Let us look at the following sequence of R statements:
> e <- new.env() > e$a <- 1 > e$a [1] 1 > e$b NULL > I think I understand the logic for returning NULL to a missing entry in an environment, but I do not think that it is fully justified. I am sure that the R developers must have seen this argument before, but I wish to call for attention to this problem again, because I think that it is important to the default safety of the R programming language. I suppose that one could argue that a good R programmer must be careful not to use NULL in any of his environment entries, but I think it is better to remove altogether this burden from the programmer and simply raise a good, old-fashioned exception when the "$" operator encounters a missing entry in an environment. The biggest advantage is that it will easily eliminate a whole class of programming error. The biggest disadvantage is that it is not backwards-compatible with old R programs. I suppose a personal solution would be to simply redefine the "$" operator in my programs. However, I really do think that the default safety of an R environment matters very much. At the very least, it would be nice to be able to configure the safety of a new environment, perhaps through a parameter. -Trishank ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
