140 lines
3.6 KiB
Perl
140 lines
3.6 KiB
Perl
package lib;
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use vars qw(@ORIG_INC);
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use Config;
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my $archname = $Config{'archname'};
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@ORIG_INC = @INC; # take a handy copy of 'original' value
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sub import {
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shift;
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foreach (reverse @_) {
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## Ignore this if not defined.
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next unless defined($_);
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if ($_ eq '') {
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require Carp;
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Carp::carp("Empty compile time value given to use lib");
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# at foo.pl line ...
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}
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if (-e && ! -d _) {
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require Carp;
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Carp::carp("Parameter to use lib must be directory, not file");
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}
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unshift(@INC, $_);
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# Put a corresponding archlib directory infront of $_ if it
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# looks like $_ has an archlib directory below it.
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if (-d "$_/$archname") {
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unshift(@INC, "$_/$archname") if -d "$_/$archname/auto";
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unshift(@INC, "$_/$archname/$]") if -d "$_/$archname/$]/auto";
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}
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}
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}
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sub unimport {
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shift;
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my $mode = shift if $_[0] =~ m/^:[A-Z]+/;
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my %names;
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foreach(@_) {
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++$names{$_};
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++$names{"$_/$archname"} if -d "$_/$archname/auto";
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}
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if ($mode and $mode eq ':ALL') {
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# Remove ALL instances of each named directory.
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@INC = grep { !exists $names{$_} } @INC;
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} else {
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# Remove INITIAL instance(s) of each named directory.
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@INC = grep { --$names{$_} < 0 } @INC;
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}
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}
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1;
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__END__
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=head1 NAME
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lib - manipulate @INC at compile time
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=head1 SYNOPSIS
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use lib LIST;
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no lib LIST;
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=head1 DESCRIPTION
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This is a small simple module which simplifies the manipulation of @INC
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at compile time.
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It is typically used to add extra directories to perl's search path so
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that later C<use> or C<require> statements will find modules which are
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not located on perl's default search path.
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=head2 ADDING DIRECTORIES TO @INC
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The parameters to C<use lib> are added to the start of the perl search
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path. Saying
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use lib LIST;
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is I<almost> the same as saying
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BEGIN { unshift(@INC, LIST) }
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For each directory in LIST (called $dir here) the lib module also
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checks to see if a directory called $dir/$archname/auto exists.
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If so the $dir/$archname directory is assumed to be a corresponding
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architecture specific directory and is added to @INC in front of $dir.
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If LIST includes both $dir and $dir/$archname then $dir/$archname will
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be added to @INC twice (if $dir/$archname/auto exists).
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=head2 DELETING DIRECTORIES FROM @INC
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You should normally only add directories to @INC. If you need to
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delete directories from @INC take care to only delete those which you
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added yourself or which you are certain are not needed by other modules
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in your script. Other modules may have added directories which they
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need for correct operation.
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By default the C<no lib> statement deletes the I<first> instance of
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each named directory from @INC. To delete multiple instances of the
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same name from @INC you can specify the name multiple times.
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To delete I<all> instances of I<all> the specified names from @INC you can
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specify ':ALL' as the first parameter of C<no lib>. For example:
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no lib qw(:ALL .);
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For each directory in LIST (called $dir here) the lib module also
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checks to see if a directory called $dir/$archname/auto exists.
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If so the $dir/$archname directory is assumed to be a corresponding
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architecture specific directory and is also deleted from @INC.
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If LIST includes both $dir and $dir/$archname then $dir/$archname will
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be deleted from @INC twice (if $dir/$archname/auto exists).
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=head2 RESTORING ORIGINAL @INC
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When the lib module is first loaded it records the current value of @INC
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in an array C<@lib::ORIG_INC>. To restore @INC to that value you
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can say
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@INC = @lib::ORIG_INC;
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=head1 SEE ALSO
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FindBin - optional module which deals with paths relative to the source file.
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=head1 AUTHOR
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Tim Bunce, 2nd June 1995.
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=cut
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