From ripley at stats.ox.ac.uk  Wed Nov 26 17:52:09 2003
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Wed Nov 26 17:51:11 2003
Subject: [Rd] Question about Unix file paths
In-Reply-To: <16324.47740.655303.232180@devzero.bogus.domain>
Message-ID: <Pine.LNX.4.44.0311261651050.14063-100000@gannet.stats>

On Wed, 26 Nov 2003, John W. Eaton wrote:

> On 26-Nov-2003, Martin Maechler <maechler@stat.math.ethz.ch> wrote:
> 
> | >>>>> " Kurt" == Kurt Hornik <Kurt.Hornik@wu-wien.ac.at>
> | >>>>>     on Wed, 26 Nov 2003 10:05:42 +0100 writes:
> | 
> |      Kurt> Right.  In any case, an explicit glob() function
> |      Kurt> seems preferable to me ...
> | 
> | Good idea!
> | 
> | More than 12 years ago, I had a similar one, and wrote  a
> | "pat2grep()" {pattern to grep regular expression} function
> | --- for S-plus on Unix ---  which I have now renamed to  glob2regexp():
> | -- still not really usable outside unix (or windows with the
> | 'sed' tool in the path), nor perfect, but maybe a good start:
> | 
> | sys <- function(...) system(paste(..., sep = ""))
> | 
> | glob2regexp <- function(pattern)
> | {
> |   ## Purpose: Change "ls pattern" to "grep regular expression" pattern.
> |   ## -------------------------------------------------------------------------
> |   ## Author: Martin Maechler ETH Zurich, ~ 1991
> |   sys("echo '", pattern, "'| sed ",
> |       "'s/\\./\\\\./g;s/*/.*/g;s/?/./g; s/^/^/;s/$/$/; s/\\.\\*\\$$//'")
> | }
> 
> It seems to me that using this approach to implement a proper glob()
> function would be more work than using the glob code that is available
> as part of bash, which I think will allow you to handle much more
> complex patterns, including [xyz] {a,b,c} etc.

Or even the glob code from Perl, which is cross-platform.  It is not clear 
to me what we would want glob() to do on Windows, BTW.

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


[Rd] Question about Unix file paths
Prof Brian Ripley