R help - Nov 2001 - package argument to library as string

The help page for library says that:

package, help: name or character string giving the name of a package.

Yet, I don't seem to be able to use a string variable here.
> version
         _                   
platform sparc-sun-solaris2.6
arch     sparc               
os       solaris2.6          
system   sparc, solaris2.6   
status                       
major    1                   
minor    3.1                 
year     2001                
month    08                  
day      31                  
language R                   
> pkg <- "ts"
> pkg
[1] "ts"
> library(pkg)
Error in library(pkg) : There is no package called
`pkg'
> library(ts)
> detach(2)
> library("ts")
> 
What am I misunderstanding? Why isn't pkg treated the same as "ts"
by library()?

Thanks,

Dave Kane
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Dave Kane <a296180 at onyx.fmr.com> (my next-door neighbor)
wrote:
>  R> pkg <- "ts"
>  R> library(pkg)
>     Error in library(pkg) : There is no package called `pkg'
You need:
R> library(pkg, character.only=TRUE)

-- 
                              -- David Brahm (brahm at alum.mit.edu)
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"David Kane  <David Kane" <a296180 at mica.fmr.com> writes:
> > pkg <- "ts"
> > pkg
> [1] "ts"
> > library(pkg)
> Error in library(pkg) : There is no package called `pkg'
> > library(ts)
> > detach(2)
> > library("ts")
> > 
> 
> What am I misunderstanding? Why isn't pkg treated the same as
"ts" by library()?
Welcome to the world of nonstandard argument evaluation... Similar
issues relate to the argument to help et al.

Basically, we have been trying to be nice to the user and allow them
to "forget" putting quotes around the package name. As a consequence,
library(pkg) might also have been intended to load someones "prototype
kernel generator" or so, and there's really no way to tell. As David
B. points out there is a way to override this.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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As seen in Dave Kane's question and my response, one needs the
"character.only"
argument to library() in order to make a loop like this work:
R> for (i in rlibs) library(i, character.only=TRUE)

It seems like a similar option would be useful for detach():
R> for (i in rlibs) detach(paste("package",i,sep=":"))  #
FAILS!
and any other functions which immediately run substitute() on their arguments.
-- 
                              -- David Brahm (brahm at alum.mit.edu)
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