Behaviour of environment(foo)<- (PR#1509)

J.C.Rougier@durham.ac.uk writes:

Hi Everyone,

I've noticed that setting the environment of a function from a package
actually creates a copy of that function in .GlobalEnv and sets the
environment on this copy:

find(.profile)

[1] "package:newblips"

environment(.profile) <- bb1$getEnv() # this is an environment
find(.profile)

[1] ".GlobalEnv"       "package:newblips"

I don't have a problem with this behaviour (now I understand it!) but
I think that it would help to document it in the help file.  May I
suggest that instead of

     The assignment form sets the environment of the function or
     formula `fun' to the `value' given.

we have

     The assignment form sets the environment of the function or
     formula \code{fun} to \code{value} if \code{fun} is in the
     current environment, otherwise it makes a copy of \code{fun} in
     the current environment and sets the environment of the copy.

I think that describes the current procedure: please correct me if I
am wrong!

But this is generic behaviour for *all* attribute assignment. It makes
no sense to describe a specific instance of it. Consider

data(airquality)
f<-function() { x <- class(airquality)<-NULL; ls() }
f()
class(airquality)