[Rd] attach() outputs messages to stdout - should it be stderr?

[Martin Maechler]

>>>>> Henrik Bengtsson <hb at biostat.ucsf.edu>
>>>>>     on Sun, 6 Apr 2014 21:33:15 -0700 writes:

    > Contrary to other functions in 'base', attach() output
    > messages to stdout instead of stdout, e.g.

    >> a <- 1 capture.output(attach(list(a=1)))
    > [1] "The following object is masked _by_ .GlobalEnv:"
    > [2] ""
    > [3] " a"

    > Shouldn't this message go to stderr?

well, it this is changed... it should be changed to use 
message() really -- as library() does.

Then, it will not only go to stderr, but also be something you can
e.g. use  suppressMessages( . )  with.

I tend to agree to change this from cat() to  message(),
and will do so after a bit of waiting..

Martin

    > Here's a patch for the local function checkConflicts() of
    > base::attach(), cf. ditto for base::library() that outputs
    > to stderr:

> Index: library/base/R/attach.R
> ===================================================================
> --- library/base/R/attach.R	(revision 65344)
> +++ library/base/R/attach.R	(working copy)
> @@ -73,7 +73,7 @@
>                                              "The following objects
> are masked %s %s:\n\n%s\n"),
>                                     if (i < db.pos) "_by_" else "from",
>                                     pkg, paste(objs, collapse="\n"))
> -                    cat(msg)
> +                    cat(msg, file = stderr())
>                  }
>              }
>          }

> /Henrik