From ripley at stats.ox.ac.uk  Tue Feb  3 09:05:55 2009
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Tue, 3 Feb 2009 08:05:55 +0000 (GMT)
Subject: [Rd] Packages should not only search for libraries with particular
 extensions and paths
Message-ID: <alpine.LFD.2.00.0901300941200.8685@gannet.stats.ox.ac.uk>

Every time I set up a new machine I find myself needing to circumvent 
the obstructions placed by a few package writers who don't understand 
enough about (compiled code) libraries.

Their mistakes include hardcoding a library extension (.so or .a) 
and/or a set of paths such as

         /usr/lib /usr/local/lib /opt/lib ...

Different OSes do have different conventions, especially where 
multiple architectures co-exist.  (E.g. most but not all x86_64 Linux 
use lib64, and Solaris uses lib/amd64 etc.)  This means that a library 
of the right name but the wrong architecture may be found in, say,
/usr/local/lib.

The correct dynamic library extension can be (at least) .so, .sl, 
.dylib or .dll.  (On Darwin aka Mac OS X dynamic libraries and shared 
objects are not the same thing, and can contain one or more 
architectures.)  But really only the linker needs to know that, and 
autoconf's AC_SEARCH_LIBS and similar are a much more reliable test. 
Even if your script finds what looks like a library in a non-standard 
place, it does not mean that either or both of the linker or the 
run-time loader ('ld.so') can find or use it.

-- 
Brian D. Ripley,                  ripley at 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] Packages should not only search for libraries with particular extensions and paths
Prof Brian Ripley