Comments in the DESCRIPTION file

On 12/06/2012 04:53 PM, William Dunlap wrote:

Why not just use some tag that R doesn't already use, say "Comment:", instead
of a #?  If you allow # in position one of a line to mean a comment then people
may expect # to be used as a comment anywhere on a line.

I would stick to whatever the DCF spec say, if there is such thing.
If the spec says # on position 1 means a comment then I think read.dcf()
should do that. Then the function can be used to read any DCF file,
not just DESCRIPTION files.

Cheers,
H.

(It may also mess up some dcf parsing code that I've written - it checks that lines
after tagged lines are either empty, the start of a new description, or start with a space,
a continuation of the previous line.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

-----Original Message-----
From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at r-project.org] On Behalf
Of Herv? Pag?s
Sent: Thursday, December 06, 2012 3:47 PM
To: Duncan Murdoch
Cc: christophe.genolini at u-paris10.fr; r-devel at r-project.org; Christophe Genolini
Subject: Re: [Rd] Comments in the DESCRIPTION file



On 12/06/2012 03:41 PM, Herv? Pag?s wrote:

Hi,

Wouldn't be hard to patch read.dcf() though.

FWIW here's the "comment aware" version of read.dcf() I've been using
for years:

   .removeCommentLines <- function(infile=stdin(), outfile=stdout())
   {
     if (is.character(infile)) {
         infile <- file(infile, "r")
         on.exit(close(infile))
     }
     if (is.character(outfile)) {
         outfile <- file(outfile, "w")
         on.exit({close(infile); close(outfile)})
     }
     while (TRUE) {
         lines <- readLines(infile, n=25000L)
         if (length(lines) == 0L)
             return()
         keep_it <- substr(lines, 1L, 1L) != "#"
         writeLines(lines[keep_it], outfile)
     }
   }

   read.dcf2 <- function(file, ...)
   {
     clean_file <- file.path(tempdir(), "clean.dcf")

mmh, would certainly be better to just use tempfile() here.

H.

     .removeCommentLines(file, clean_file)
     on.exit(file.remove(clean_file))
     read.dcf(clean_file, ...)
   }

Cheers,
H.

On 11/07/2012 01:53 AM, Duncan Murdoch wrote:

On 12-11-07 4:26 AM, Christophe Genolini wrote:

Hi all,

Is it possible to add comments in the DESCRIPTION file?

The read.dcf function is used to read the DESCRIPTION file, and it
doesn't support comments.  (The current Debian control format
description does appear to support comments with leading # markers, but
R's read.dcf function doesn't support these.)

You could probably get away with something like

#: this is a comment

since unrecognized fields are ignored, but I think this fact is
undocumented so I would say it's safer to assume that comments are not
supported.

Duncan Murdoch

--
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fhcrc.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fhcrc.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319