classed

classed <- function (x, cls)
{
    class(x) <- cls
    x
}

If it doesn't use copy-on-write then the result will be additional
slowdown when all your data is copied again and again (I guess it depends
on how big the object is).

I've often wondered about this. Any comments from someone who really knows the
internals of R? When I first implemented it I did some testing and didn't notice
any really big slowdown and I do use a lot of fairly big (multi MB size)
objects. But notice that the difference is really in the function call, not in
the copying of objects. A function using classed would end

  classed(x, "whatever") }

rather than

 class(x) <- "whatever"
 x}

I think the copy is (or is not) made in both cases.

Paul Gilbert



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