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[perl #37260] A fix to a bug of sample code for finding modules in perlfaq3.pod

From:
Taro Kawagishi
Date:
September 25, 2005 03:16
Subject:
[perl #37260] A fix to a bug of sample code for finding modules in perlfaq3.pod
Message ID:
rt-3.0.11-37260-121356.11.5304740718734@perl.org
# New Ticket Created by  Taro Kawagishi 
# Please include the string:  [perl #37260]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/rt3/Ticket/Display.html?id=37260 >


This is a bug report for perl from tarok@acm.org,
generated with the help of perlbug 1.35 running under perl v5.8.7.

A bug report for Perl v5.8.7

Reporter email:	tarok@acm.org

perlfaq3.pod document in the core Perl package has a section
	"How do I find which modules are installed on my system?"
where it gives a sample code to list available Perl modules on the system.

I found the sample code

	use File::Find::Rule;
	my @files = File::Find::Rule->file()->name( '*.pm' )->in( @INC );

and

    use File::Find;
    my @files;
    find sub { push @files, $File::Find::name if -f _ && /\.pm$/ },
         @INC;
	print join "\n", @files;

don't give a complete result on UNIX systems in case a directory path in @INC is a symbolic link and doesn't have the corresponding actual directory in @INC.

For example on my Debian system @INC is set to 
('/etc/perl' '/usr/local/lib/perl/5.8.7' '/usr/local/share/perl/5.8.7' '/usr/lib/perl5' '/usr/share/perl5' '/usr/lib/perl/5.8' '/usr/share/perl/5.8' '/usr/local/lib/site_perl' '.')
and '/usr/lib/perl/5.8' is a symbolic link to '/usr/lib/perl/5.8.7'.
Then the code will never list modules in '/usr/lib/perl/5.8' nor '/usr/lib/perl/5.8.7',
because File::Find::find doesn't work on a symlink directory unless the follow option is enabled.

Giving the follow option will slow the processing if @INC includes '/usr/lib/perl/5.8.7' too,
so I think it would be better to change @INC to include only actual directories before passing to find.

My modification is as follows:

use strict;
use File::Find;
my @files;

# First take away '.' from @INC
@INC = grep { $_ !~ /^[.]$/ } @INC;
my @INC_ACTUAL;
for my $dir (@INC) {
	# replace a symbolic link with the actual directory name.
	if (-l $dir) {
		my $parent;
		($parent = $dir) =~ s|/[^/]+/?$||;
		$dir = $parent .'/'. readlink($dir);
	}
	push @INC_ACTUAL, $dir;
}

find sub { push @files, $File::Find::name if -f _ && /\.pm$/ }, @INC_ACTUAL;

print join "\n", @files;
print "\n";
---
Flags:
    category=docs
    severity=low
---
Site configuration information for perl v5.8.7:

Configured by Debian Project at Thu Jun  9 00:24:12 EST 2005.

Summary of my perl5 (revision 5 version 8 subversion 7) configuration:
  Platform:
    osname=linux, osvers=2.4.28, archname=powerpc-linux-thread-multi
    uname='linux vir 2.4.28 #1 sat jan 22 13:44:23 est 2005 ppc gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=powerpc-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.8.7 -Dsitearch=/usr/local/lib/perl/5.8.7 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dlibperl=libperl.so.5.8.7 -Dd_dosuid -des'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='3.3.6 (Debian 1:3.3.6-5.0.1)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=4321
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so.5.8.7
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.7:
    /etc/perl
    /usr/local/lib/perl/5.8.7
    /usr/local/share/perl/5.8.7
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
    .

---
Environment for perl v5.8.7:
    HOME=/home/tarok
    LANG=C
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash




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