R devel - Dec 2000 - unlink() is not synchronized with existing connections (PR#783)

> # creating a file
> cat("sddfasdf", file="tempfile")
> showConnections()
     class description mode text isopen can read can
write
> con <- file("tempfile", "r")
> readLines(con)
[1] "sddfasdf"
Warning message: 
incomplete final line in: readLines(con, n, ok) 
> showConnections()
  class      description mode text   isopen   can read can write
3 "tempfile" "file"      "r"  "text"
"opened" "yes"    "no"    
> unlink("tempfile")
> showConnections()
  class      description mode text   isopen   can read can write
3 "tempfile" "file"      "r"  "text"
"opened" "yes"    "no"    
> # now we have an opened (read) connection to a non-existing file left
BTW: this may be considered as a special case of a more general thing: 
undefined rights to modify/access connections owned by other parts of the
software


Regards


Jens Oehlschlägel


--please do not edit the information below--

Version:
 platform = i386-pc-mingw32
 arch = x86
 os = Win32
 system = x86, Win32
 status = 
 major = 1
 minor = 2.0
 year = 2000
 month = 12
 day = 15
 language = R

Windows NT 4.0 (build 1381) Service Pack 6

Search Path:
 .GlobalEnv, package:ctest, Autoloads, package:base

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On Wed, 20 Dec 2000 joehl@web.de wrote:
> > # creating a file
> > cat("sddfasdf", file="tempfile")
> > showConnections()
>      class description mode text isopen can read can write
> > con <- file("tempfile", "r")
> > readLines(con)
> [1] "sddfasdf"
> Warning message: 
> incomplete final line in: readLines(con, n, ok) 
> > showConnections()
>   class      description mode text   isopen   can read can write
> 3 "tempfile" "file"      "r" 
"text" "opened" "yes"    "no"
> > unlink("tempfile")
> > showConnections()
>   class      description mode text   isopen   can read can write
> 3 "tempfile" "file"      "r" 
"text" "opened" "yes"    "no"
> > # now we have an opened (read) connection to a non-existing file left
What's the problem?  That's perfectly valid on OSes that support it
(e.g.
Unix and Windows NT).  Unlinked files are *not* `non-existing'.
> cat("sddfasdf", file="tempfile")
> con <- file("tempfile", "r")
> unlink("tempfile")
> readLines(con)
[1] "sddfasdf"
Warning message: 
incomplete final line in: readLines(con, n, ok) 
> close(con)

I am not sure what your point is here.  Connections are experimental and
we know it is possible to do silly things with them.  But why would one?


-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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