R help - Jul 2012 - locked binding of setwd() in R 2.15.x causes .Rprofile to fail

[Env: Win XP, R 2.14.2, R 2.15.0]

I have a replacement function for setwd() in my .Rprofile which displays 
the current R path in the R window
title. It no longer works in R 2.15.x, giving the error below. Worse, 
the error prevents the rest of my
.Rprofile script from completing.

Is there some way to rescue this, i.e., preserve this behavior in
R 2.15? If not, how can I modify my script so it will still work under R 
2.14.2 and not fail under R 2.15?

Error in utils::assignInNamespace("setwd", function(dir) { :
locked binding of ?setwd? cannot be changed

######################
#-- functions from .Rprofile
# modify setwd() to also show the current path in the window title
# assigns .lastdir in the global environment
local({
oldsetwd <- setwd
utils::assignInNamespace("setwd",
function(dir) {
.lastdir <<- oldsetwd(dir)
utils::setWindowTitle( short.path(base::getwd()) )
.lastdir
}, "base")
})

# setwd replacement, allowing cd() to be like 'cd -' on unix (return to 
last dir)
cd <- function(dir) {
if(missing(dir)) dir <- .lastdir
.lastdir <<- base::setwd(dir)
utils::setWindowTitle( short.path(base::getwd()) )
}

short.path <- function(dir, len=2) {
np <-length(parts <- unlist(strsplit(dir, '/')))
parts <-rev( rev(parts)[1:min(np,len)] )
dots <- ifelse (np>len, '...', '')
paste(dots,paste(parts, '/', sep='', collapse=''))
}

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

Does trace() do what you want from a .Rprofile file?  It works
from the command line:

  > trace(setwd,print=FALSE,quote(options(prompt=paste0(dir,">
"))))
  Tracing function "setwd" in
  package "base"
  [1] "setwd"
  > setwd("z:/")
  z:/> getwd()
  [1] "z:/"
  z:/> setwd("c:/temp")
  c:/temp> pi
  [1] 3.141593
  c:/temp>

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf
> Of Michael Friendly
> Sent: Monday, July 30, 2012 8:11 AM
> To: R-help
> Subject: [R] locked binding of setwd() in R 2.15.x causes .Rprofile to fail
> 
> [Env: Win XP, R 2.14.2, R 2.15.0]
> 
> I have a replacement function for setwd() in my .Rprofile which displays
> the current R path in the R window
> title. It no longer works in R 2.15.x, giving the error below. Worse,
> the error prevents the rest of my
> .Rprofile script from completing.
> 
> Is there some way to rescue this, i.e., preserve this behavior in
> R 2.15? If not, how can I modify my script so it will still work under R
> 2.14.2 and not fail under R 2.15?
> 
> Error in utils::assignInNamespace("setwd", function(dir) { :
> locked binding of 'setwd' cannot be changed
> 
> ######################
> #-- functions from .Rprofile
> # modify setwd() to also show the current path in the window title
> # assigns .lastdir in the global environment
> local({
> oldsetwd <- setwd
> utils::assignInNamespace("setwd",
> function(dir) {
> .lastdir <<- oldsetwd(dir)
> utils::setWindowTitle( short.path(base::getwd()) )
> .lastdir
> }, "base")
> })
> 
> # setwd replacement, allowing cd() to be like 'cd -' on unix
(return to
> last dir)
> cd <- function(dir) {
> if(missing(dir)) dir <- .lastdir
> .lastdir <<- base::setwd(dir)
> utils::setWindowTitle( short.path(base::getwd()) )
> }
> 
> short.path <- function(dir, len=2) {
> np <-length(parts <- unlist(strsplit(dir, '/')))
> parts <-rev( rev(parts)[1:min(np,len)] )
> dots <- ifelse (np>len, '...', '')
> paste(dots,paste(parts, '/', sep='', collapse=''))
> }
> 
> --
> Michael Friendly     Email: friendly AT yorku DOT ca
> Professor, Psychology Dept.
> York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
> 4700 Keele Street    Web:   http://www.datavis.ca
> Toronto, ONT  M3J 1P3 CANADA
> 
> ______________________________________________
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