[Rd] classed

Paul Gilbert pgilbert@bank-banque-canada.ca
Fri, 15 Sep 2000 11:53:04 -0400

>> 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"

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

Paul Gilbert

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