> Duncan Murdoch writes:
> The source to the noquote() function looks like this:
> noquote <- function(obj, right = FALSE) {
> ## constructor for a useful "minor" class
> if(!inherits(obj,"noquote"))
> class(obj) <- c(attr(obj, "class"),
> if(right) c(right = "noquote") else "noquote")
> obj
> }
> Notice what happens with right = TRUE:
>> x <- noquote("a", right = TRUE)
>> x
> [1] a
>> class(x)
> right
> "noquote"
> The class vector for x is named. The print method pays attention to the
> name, so we get different behaviour for a class of "noquote" and a class
> of c(right = "noquote").
> I had never noticed a named class vector before, and it raised some
> questions for me:
> - Is this used anywhere else?
Not that I'd be aware of: I think MMae is the expert here.
> - Are names preserved in all the operations normally done on a class
> vector? (As far as I can see they are, but maybe I've missed something.)
> - Is it a good idea to encode a string value worth of information in the
> name, rather than setting the class to something like c("noquote",
> "right") instead?
My preference would be to have unnamed class vectors, so that the names
could perhaps eventually be used to store the name of the package which
owns the class. For noquote, I guess you'd want something like
c("noquote_right", "noquote")
Best
-k
> Comments would be welcome.
> Duncan Murdoch
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