lib(3pm) Perl Programmers Reference Guide lib(3pm)
NAME
lib - manipulate @INC at compile time
SYNOPSIS
use lib LIST;
no lib LIST;
DESCRIPTION
This is a small simple module which simplifies the manipulation of @INC
at compile time.
It is typically used to add extra directories to perl's search path so
that later "use" or "require" statements will find modules which are
not located on perl's default search path.
Adding directories to @INC
The parameters to "use lib" are added to the start of the perl search
path. Saying
use lib LIST;
is almost the same as saying
BEGIN { unshift(@INC, LIST) }
For each directory in LIST (called $dir here) the lib module also
checks to see if a directory called $dir/$archname/auto exists. If so
the $dir/$archname directory is assumed to be a corresponding
architecture specific directory and is added to @INC in front of $dir.
lib.pm also checks if directories called $dir/$version and
$dir/$version/$archname exist and adds these directories to @INC.
The current value of $archname can be found with this command:
perl -V:archname
The corresponding command to get the current value of $version is:
perl -V:version
To avoid memory leaks, all trailing duplicate entries in @INC are
removed.
Deleting directories from @INC
You should normally only add directories to @INC. If you need to
delete directories from @INC take care to only delete those which you
added yourself or which you are certain are not needed by other modules
in your script. Other modules may have added directories which they
need for correct operation.
The "no lib" statement deletes all instances of each named directory
from @INC.
For each directory in LIST (called $dir here) the lib module also
checks to see if a directory called $dir/$archname/auto exists. If so
the $dir/$archname directory is assumed to be a corresponding
architecture specific directory and is also deleted from @INC. lib.pm
also checks if directories called $dir/$version and
$dir/$version/$archname exist and deletes these directories from @INC.
Restoring original @INC
When the lib module is first loaded it records the current value of
@INC in an array @lib::ORIG_INC. To restore @INC to that value you can
say
@INC = @lib::ORIG_INC;
CAVEATS
In order to keep lib.pm small and simple, it only works with Unix
filepaths. This doesn't mean it only works on Unix, but non-Unix users
must first translate their file paths to Unix conventions.
# VMS users wanting to put [.stuff.moo] into
# their @INC would write
use lib 'stuff/moo';
NOTES
In the future, this module will likely use File::Spec for determining
paths, as it does now for Mac OS (where Unix-style or Mac-style paths
work, and Unix-style paths are converted properly to Mac-style paths
before being added to @INC).
If you try to add a file to @INC as follows:
use lib 'this_is_a_file.txt';
"lib" will warn about this. The sole exceptions are files with the
".par" extension which are intended to be used as libraries.
SEE ALSO
FindBin(3) - optional module which deals with paths relative to the
source file.
PAR(3) - optional module which can treat ".par" files as Perl libraries.
AUTHOR
Tim Bunce, 2nd June 1995.
"lib" is maintained by the perl5-porters. Please direct any questions
to the canonical mailing list. Anything that is applicable to the CPAN
release can be sent to its maintainer, though.
Maintainer: The Perl5-Porters <perl5-porters@perl.org>
Maintainer of the CPAN release: Steffen Mueller <smueller@cpan.org>
COPYRIGHT AND LICENSE
This package has been part of the perl core since perl 5.001. It has
been released separately to CPAN so older installations can benefit
from bug fixes.
This package has the same copyright and license as the perl core.
perl v5.30.3 2020-06-03 lib(3pm)
perl 5.30.3 - Generated Thu Jun 4 16:39:37 CDT 2020