[Rd] Structure of the object: list() and attr()

[Gabor Grothendieck]

The key issue is inheritance. If you use a data frame with attributes then
you can inherit data frame methods without further definition,
e.g.

   x <- structure(data.frame(a = 1:10), my.attr = 33,
       class = c("myclass", "data.frame"))
   dim(x)  # inherit dim method

but if you do it this way then you need to define your own methods
for each one you want:

   x <- structure(list(.Data = data.frame(a = 1:10), my.attr = 33),
class = "myclass")
   dim.myclass <- function(x) dim(x$.Data)
   dim(x)

for every method you want.


On 8/1/06, Gorjanc Gregor <Gregor.Gorjanc at bfro.uni-lj.si> wrote:
> Hello!
>
> I am writing code where I define objects with new class. When I started,
> it was a simple data.frame with attributes, but it is getting more evolved
> and I would like to hear any pros and cons to go for list structure,
> where one "slot" would be a data.frame, while other "slots" would take over
> role of attributes.
>
> Lep pozdrav / With regards,
>    Gregor Gorjanc
>
> ----------------------------------------------------------------------
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