indexing operation removes attributes

Question

Apparently, indexing a list with attributes returns a list without the attributes.

> l <- list(a=1:3, b=7)
> attr(l, \'x\') <- 67
> l
$a
[1] 1         


        

Answer 1

Use the sticky package. It was designed exactly for this purpose. (Full Disclosure: I am the package author.) It's simple to use, just call sticky() on your vector/list/etc. For example:

> l <- list(a=1:3, b=7)
> attr(l, 'x') <- 67    
> l <- sticky(l) 
> attr(l,'x')  
> [1] 67
>
> class(l)
> [1] "sticky" "list"