R devel - Jun 2003 - library(grid) : .First.lib fails (PR#3347)

Dear r-bugs,

I'm having problems loading the 'grid' package when it has been
detached
earlier in the same session:
> library(grid)
> detach("package:grid")
> library(grid)
Error in .Call("L_initGrid", PACKAGE = "grid") :
        .Call function name not in load table
Error in library(grid) : .First.lib failed

This bug was mentioned on r-help some time ago
(www.stat.math.ethz.ch/pipermail/r-help/2002-January/016904.html), but I
don't think it has entered the bug tracking system yet. The bug is
relevant for me since it crashes functions I use for package maintenance.

Regards,
Arni

OS:   Windows XP
R:    1.7.1
grid: 0.7.4

On Fri, 27 Jun 2003 arnima@u.washington.edu wrote:
> I'm having problems loading the 'grid' package when it has been
detached
> earlier in the same session:
> 
> > library(grid)
> > detach("package:grid")
> > library(grid)
> Error in .Call("L_initGrid", PACKAGE = "grid") :
>         .Call function name not in load table
> Error in library(grid) : .First.lib failed
> 
> This bug was mentioned on r-help some time ago
> (www.stat.math.ethz.ch/pipermail/r-help/2002-January/016904.html), but I
> don't think it has entered the bug tracking system yet. The bug is
> relevant for me since it crashes functions I use for package maintenance.
[That has nothing to do with this: it was a broken Windows build of R
1.4.0 on CRAN, and that message says that it was fixed in the next build.]


Basically, what you are doing is not supported.  Don't detach packages you 
want to re-use.  With the sort of amount of memory people have these days, 
it makes little sense ever to detach packages. (It does not unload the DLL 
in general, and grid is a rare exception.)

The specific issue is that grid contains a .Last.lib which does unload the 
DLL but does not unregister it. It needs to be

.Last.lib <-function(libpath) {
  if (.grid.loaded) {
    # Kill all existing devices to avoid replay
    # of display list which tries to run grid code
    # Not very friendly to other registered graphics systems
    # but its safety first for now
    graphics.off()
    .Call("L_killGrid", PACKAGE="grid")
    dyn.unload(paste(libpath, "libs",
                     paste("grid", .Platform$dynlib.ext,
sep=""),
                     sep=.Platform$file.sep))
   .dynLibs(.Dyn.libs[-match("grid", .dynLibs()])
  }
}

and note the comment there.  (Paul: please use file.path is the dyn.unload 
call.)


-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595