rm() deletes 'c' if c('a','b') is the argument (PR#9399)

Steven McKinney wrote:

Same behaviour seen on Apple Mac OSX 10.4.8 platform:

  

sessionInfo()
    

R version 2.4.0 Patched (2006-10-31 r39758) 
powerpc-apple-darwin8.8.0 

locale:
en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8

attached base packages:
[1] "methods"   "stats"     "graphics"  "grDevices" "utils"     "datasets"  "base"     

other attached packages:
    XML 
"1.2-0" 
  

ls()
    

[1] "getMonograph" "last.warning" "myfun"       
  

a <- 1
b <- 2
c <- letters
a
    

[1] 1
  

b
    

[1] 2
  

c
    

 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"
  

rm(c('a', 'b'))
a
    

Error: object "a" not found
  

b
    

Error: object "b" not found
  

c
    

.Primitive("c")
  

ls()
    

[1] "getMonograph" "last.warning" "myfun"       
  

a <- 1
b <- 2
d <- letters
ls()
    

[1] "a"            "b"            "d"            "getMonograph" "last.warning" "myfun"       
  

rm(c('a', 'b'))
    

Warning message:
remove: variable "c" was not found 
  

ls()
    

[1] "d"            "getMonograph" "last.warning" "myfun"       
  

Steven McKinney

Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre

email: smckinney at bccrc.ca

tel: 604-675-8000 x7561

BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C. 
V5Z 1L3
Canada




-----Original Message-----
From: r-devel-bounces at r-project.org on behalf of hanl2 at wyeth.com
Sent: Wed 11/29/2006 10:35 AM
To: r-devel at stat.math.ethz.ch
Cc: R-bugs at biostat.ku.dk
Subject: [Rd] rm() deletes 'c' if c('a','b') is the argument (PR#9399)
 
Full_Name: Lixin Han
Version: 2.4.0
OS: Windows 2000
Submission from: (NULL) (155.94.110.222)


A character vector c('a','b') is supplied to rm().  As a result, 'c' is deleted
unintentionally.

  

a <- 1:5
b <- 'abc'
c <- letters
ls()
    

[1] "a" "b" "c"
  

rm(c('a','b'))
ls()
    

character(0)
  

  

The reason is that

 > x <- function(...) sapply(match.call(expand.dots = FALSE)$..., 

as.character)

 > x(c(a,b))

     [,1]
[1,] "c"
[2,] "a"
[3,] "b"

Which in turn happens because

 > as.character(quote(c(a,b)))

[1] "c" "a" "b"

I don't know if it really qualifies as a bug, but it's not documented 
that as.character() is used and I suppose we could be more careful with 
the argument checking.