package lib; use vars qw(@ORIG_INC); use Config; my $archname = $Config{'archname'}; @ORIG_INC = @INC; # take a handy copy of 'original' value sub import { shift; my %names; foreach (reverse @_) { if ($_ eq '') { require Carp; Carp::carp("Empty compile time value given to use lib"); } if (-e && ! -d _) { require Carp; Carp::carp("Parameter to use lib must be directory, not file"); } unshift(@INC, $_); # Put a corresponding archlib directory infront of $_ if it # looks like $_ has an archlib directory below it. if (-d "$_/$archname") { unshift(@INC, "$_/$archname") if -d "$_/$archname/auto"; unshift(@INC, "$_/$archname/$]") if -d "$_/$archname/$]/auto"; } } # remove trailing duplicates @INC = grep { ++$names{$_} == 1 } @INC; return; } sub unimport { shift; my %names; foreach (@_) { ++$names{$_}; ++$names{"$_/$archname"} if -d "$_/$archname/auto"; } # Remove ALL instances of each named directory. @INC = grep { !exists $names{$_} } @INC; return; } 1; __END__ =head1 NAME lib - manipulate @INC at compile time =head1 SYNOPSIS use lib LIST; no lib LIST; =head1 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 C or C statements will find modules which are not located on perl's default search path. =head2 Adding directories to @INC The parameters to C are added to the start of the perl search path. Saying use lib LIST; is I 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. To avoid memory leaks, all trailing duplicate entries in @INC are removed. =head2 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 C 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. =head2 Restoring original @INC When the lib module is first loaded it records the current value of @INC in an array C<@lib::ORIG_INC>. To restore @INC to that value you can say @INC = @lib::ORIG_INC; =head1 SEE ALSO FindBin - optional module which deals with paths relative to the source file. =head1 AUTHOR Tim Bunce, 2nd June 1995. =cut