R devel - Dec 2000 - Problem with sink() in 1.20 on Windows (PR#779)

When I use sink(filename) to save the results of the run, the file
does not seem to be closed or released back to the OS after I issue
the "sink()" command.  Here is a baby example:

sink("test.txt")
tdta <- data.frame(x = x <- 0:10,y = 2 * x + rnorm(11))

print(summary(lm(y ~ x, data=tdta)))
sink()

At this point (even after refreshing the Explorer window) the filesize of
"test.txt" is listed as 0 bytes, and as long as Rgui is running, I
cannot delete the file.  Emacs cannot read the file (but Notepad can).  This
happens both in the gui
and when the commands are in a file run via "source()".

--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 9x 4.10 (build 1998)

Search Path:
 .GlobalEnv, Autoloads, package:base

R. Woodrow Setzer, Jr.                                            Phone:
(919) 541-0128
Experimental Toxicology Division                       Fax:  (919) 541-5394
Pharmacokinetics Branch
NHEERL MD-74; US EPA; RTP, NC 27711


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On Tue, 19 Dec 2000 Setzer.Woodrow@epamail.epa.gov wrote:
> When I use sink(filename) to save the results of the run, the file
> does not seem to be closed or released back to the OS after I issue
> the "sink()" command.  Here is a baby example:
sink works on connections, not files, as from 1.2.0.
> sink("test.txt")
> tdta <- data.frame(x = x <- 0:10,y = 2 * x + rnorm(11))
> 
> print(summary(lm(y ~ x, data=tdta)))
> sink()
> 
> At this point (even after refreshing the Explorer window) the filesize of
> "test.txt" is listed as 0 bytes, and as long as Rgui is running,
I
> cannot delete the file.  Emacs cannot read the file (but Notepad can). 
This happens both in the gui
> and when the commands are in a file run via "source()".
Yes, but what is the bug exactly?  The connection is still open so you can
switch output back to it.  If you want different behaviour, you can open a
connection and close it yourself.  As in

zz <- file("test.txt", "w")
sink(zz)
tdta <- data.frame(x = x <- 0:10,y = 2 * x + rnorm(11))
print(summary(lm(y ~ x, data=tdta)))
sink()
close(zz)

It might be better to close the file as well as the connection when
switching, but that is not what was done.  To do that use

sink <- function (file = NULL, append = FALSE) 
{
    if (is.null(file)) 
        file <- 1
    else if (is.character(file)) { 
        file <- file(file, ifelse(append, "a", "w"))
        on.exit(close(file))
    } else if (!inherits(file, "connection")) 
        stop("`file' must be NULL, a connection or a character
string")
    .Internal(sink(file, append))
}

(One possible cause of confusion is that the connection might be closed,
but not the file.)

-- 
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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Dear Prof. Ripley,

You wrote
> Yes, but what is the bug exactly?  
Just testing connections, I think the bug is that the help for sink says that:

  If `file' is a connection if will be opened if necessary.
     Switching to another file or connection closes the existing
     connection unless it is the console.

and after switching to another file or connection the existing connection is not
closed.
> showConnections()
     class description mode text isopen can read can
write
> sink("tempfile")
> sink()
> showConnections()
  class      description mode text   isopen   can read can write
3 "tempfile" "file"      "w"  "text"
"opened" "no"     "yes"   
> # now we have silently an open connection left
I tend to think that a sequence of

 sink(WhateverConnectionInvolved)
 :
 :
 sink()

should leave WhateverConnectionInvolved in the same state it was before the
sequence.
i.e. if WhateverConnectionInvolved was non.existent it should be non.existent
i.e. if WhateverConnectionInvolved was existent but not opened it should be
existent but not opened
i.e. if WhateverConnectionInvolved was existent and opened it should be existent
and opened

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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