1 # -*- mode: cperl; tab-width: 8; indent-tabs-mode: nil; basic-offset: 2 -*-
2 # vim:ts=8:sw=2:et:sta:sts=2
3 package Module::Metadata;
5 # Adapted from Perl-licensed code originally distributed with
6 # Module-Build by Ken Williams
8 # This module provides routines to gather information about
9 # perl modules (assuming this may be expanded in the distant
10 # parrot future to look at other types of modules).
15 our $VERSION = '1.000016';
16 $VERSION = eval $VERSION;
23 if ($INC{'Log/Contextual.pm'}) {
24 Log::Contextual->import('log_info');
26 *log_info = sub (&) { warn $_[0]->() };
29 use File::Find qw(find);
31 my $V_NUM_REGEXP = qr{v?[0-9._]+}; # crudely, a v-string or decimal
33 my $PKG_FIRST_WORD_REGEXP = qr{ # the FIRST word in a package name
34 [a-zA-Z_] # the first word CANNOT start with a digit
36 [\w']? # can contain letters, digits, _, or ticks
37 \w # But, NO multi-ticks or trailing ticks
41 my $PKG_ADDL_WORD_REGEXP = qr{ # the 2nd+ word in a package name
42 \w # the 2nd+ word CAN start with digits
44 [\w']? # and can contain letters or ticks
45 \w # But, NO multi-ticks or trailing ticks
49 my $PKG_NAME_REGEXP = qr{ # match a package name
50 (?: :: )? # a pkg name can start with aristotle
51 $PKG_FIRST_WORD_REGEXP # a package word
53 (?: :: )+ ### aristotle (allow one or many times)
54 $PKG_ADDL_WORD_REGEXP ### a package word
55 )* # ^ zero, one or many times
57 :: # allow trailing aristotle
61 my $PKG_REGEXP = qr{ # match a package declaration
62 ^[\s\{;]* # intro chars on a line
63 package # the word 'package'
65 ($PKG_NAME_REGEXP) # a package name
66 \s* # optional whitespace
67 ($V_NUM_REGEXP)? # optional version number
68 \s* # optional whitesapce
69 [;\{] # semicolon line terminator or block start (since 5.16)
72 my $VARNAME_REGEXP = qr{ # match fully-qualified VERSION name
73 ([\$*]) # sigil - $ or *
75 ( # optional leading package name
76 (?:::|\')? # possibly starting like just :: (Ì la $::VERSION)
77 (?:\w+(?:::|\'))* # Foo::Bar:: ...
83 my $VERS_REGEXP = qr{ # match a VERSION definition
85 \(\s*$VARNAME_REGEXP\s*\) # with parens
87 $VARNAME_REGEXP # without parens
90 =[^=~] # = but not ==, nor =~
95 my $filename = File::Spec->rel2abs( shift );
97 return undef unless defined( $filename ) && -f $filename;
98 return $class->_init(undef, $filename, @_);
101 sub new_from_handle {
104 my $filename = shift;
105 return undef unless defined($handle) && defined($filename);
106 $filename = File::Spec->rel2abs( $filename );
108 return $class->_init(undef, $filename, @_, handle => $handle);
113 sub new_from_module {
118 $props{inc} ||= \@INC;
119 my $filename = $class->find_module_by_name( $module, $props{inc} );
120 return undef unless defined( $filename ) && -f $filename;
121 return $class->_init($module, $filename, %props);
126 my $compare_versions = sub {
127 my ($v1, $op, $v2) = @_;
128 $v1 = version->new($v1)
129 unless UNIVERSAL::isa($v1,'version');
131 my $eval_str = "\$v1 $op \$v2";
132 my $result = eval $eval_str;
133 log_info { "error comparing versions: '$eval_str' $@" } if $@;
138 my $normalize_version = sub {
140 if ( $version =~ /[=<>!,]/ ) { # logic, not just version
141 # take as is without modification
143 elsif ( ref $version eq 'version' ) { # version objects
144 $version = $version->is_qv ? $version->normal : $version->stringify;
146 elsif ( $version =~ /^[^v][^.]*\.[^.]+\./ ) { # no leading v, multiple dots
147 # normalize string tuples without "v": "1.2.3" -> "v1.2.3"
148 $version = "v$version";
156 # separate out some of the conflict resolution logic
158 my $resolve_module_versions = sub {
159 my $packages = shift;
161 my( $file, $version );
163 foreach my $p ( @$packages ) {
164 if ( defined( $p->{version} ) ) {
165 if ( defined( $version ) ) {
166 if ( $compare_versions->( $version, '!=', $p->{version} ) ) {
167 $err .= " $p->{file} ($p->{version})\n";
169 # same version declared multiple times, ignore
173 $version = $p->{version};
176 $file ||= $p->{file} if defined( $p->{file} );
180 $err = " $file ($version)\n" . $err;
195 croak "provides() requires key/value pairs \n" if @_ % 2;
198 croak "provides() takes only one of 'dir' or 'files'\n"
199 if $args{dir} && $args{files};
201 croak "provides() requires a 'version' argument"
202 unless defined $args{version};
204 croak "provides() does not support version '$args{version}' metadata"
205 unless grep { $args{version} eq $_ } qw/1.4 2/;
207 $args{prefix} = 'lib' unless defined $args{prefix};
211 $p = $class->package_versions_from_directory($args{dir});
214 croak "provides() requires 'files' to be an array reference\n"
215 unless ref $args{files} eq 'ARRAY';
216 $p = $class->package_versions_from_directory($args{files});
219 # Now, fix up files with prefix
220 if ( length $args{prefix} ) { # check in case disabled with q{}
221 $args{prefix} =~ s{/$}{};
222 for my $v ( values %$p ) {
223 $v->{file} = "$args{prefix}/$v->{file}";
230 sub package_versions_from_directory {
231 my ( $class, $dir, $files ) = @_;
240 push @files, $_ if -f $_ && /\.pm$/;
246 # First, we enumerate all packages & versions,
247 # separating into primary & alternative candidates
249 foreach my $file (@files) {
250 my $mapped_filename = File::Spec::Unix->abs2rel( $file, $dir );
251 my @path = split( /\//, $mapped_filename );
252 (my $prime_package = join( '::', @path )) =~ s/\.pm$//;
254 my $pm_info = $class->new_from_file( $file );
256 foreach my $package ( $pm_info->packages_inside ) {
257 next if $package eq 'main'; # main can appear numerous times, ignore
258 next if $package eq 'DB'; # special debugging package, ignore
259 next if grep /^_/, split( /::/, $package ); # private package, ignore
261 my $version = $pm_info->version( $package );
263 $prime_package = $package if lc($prime_package) eq lc($package);
264 if ( $package eq $prime_package ) {
265 if ( exists( $prime{$package} ) ) {
266 croak "Unexpected conflict in '$package'; multiple versions found.\n";
268 $mapped_filename = "$package.pm" if lc("$package.pm") eq lc($mapped_filename);
269 $prime{$package}{file} = $mapped_filename;
270 $prime{$package}{version} = $version if defined( $version );
273 push( @{$alt{$package}}, {
274 file => $mapped_filename,
281 # Then we iterate over all the packages found above, identifying conflicts
282 # and selecting the "best" candidate for recording the file & version
284 foreach my $package ( keys( %alt ) ) {
285 my $result = $resolve_module_versions->( $alt{$package} );
287 if ( exists( $prime{$package} ) ) { # primary package selected
289 if ( $result->{err} ) {
290 # Use the selected primary package, but there are conflicting
291 # errors among multiple alternative packages that need to be
294 "Found conflicting versions for package '$package'\n" .
295 " $prime{$package}{file} ($prime{$package}{version})\n" .
299 } elsif ( defined( $result->{version} ) ) {
300 # There is a primary package selected, and exactly one
301 # alternative package
303 if ( exists( $prime{$package}{version} ) &&
304 defined( $prime{$package}{version} ) ) {
305 # Unless the version of the primary package agrees with the
306 # version of the alternative package, report a conflict
307 if ( $compare_versions->(
308 $prime{$package}{version}, '!=', $result->{version}
313 "Found conflicting versions for package '$package'\n" .
314 " $prime{$package}{file} ($prime{$package}{version})\n" .
315 " $result->{file} ($result->{version})\n"
320 # The prime package selected has no version so, we choose to
321 # use any alternative package that does have a version
322 $prime{$package}{file} = $result->{file};
323 $prime{$package}{version} = $result->{version};
327 # no alt package found with a version, but we have a prime
328 # package so we use it whether it has a version or not
331 } else { # No primary package was selected, use the best alternative
333 if ( $result->{err} ) {
335 "Found conflicting versions for package '$package'\n" .
340 # Despite possible conflicting versions, we choose to record
341 # something rather than nothing
342 $prime{$package}{file} = $result->{file};
343 $prime{$package}{version} = $result->{version}
344 if defined( $result->{version} );
348 # Normalize versions. Can't use exists() here because of bug in YAML::Node.
349 # XXX "bug in YAML::Node" comment seems irrelevant -- dagolden, 2009-05-18
350 for (grep defined $_->{version}, values %prime) {
351 $_->{version} = $normalize_version->( $_->{version} );
362 my $filename = shift;
365 my $handle = delete $props{handle};
366 my( %valid_props, @valid_props );
367 @valid_props = qw( collect_pod inc );
368 @valid_props{@valid_props} = delete( @props{@valid_props} );
369 warn "Unknown properties: @{[keys %props]}\n" if scalar( %props );
373 filename => $filename,
384 my $self = bless(\%data, $class);
387 $self->_parse_fh($handle);
390 $self->_parse_file();
393 unless($self->{module} and length($self->{module})) {
394 my ($v, $d, $f) = File::Spec->splitpath($self->{filename});
397 my @candidates = grep /$f$/, @{$self->{packages}};
398 $self->{module} = shift(@candidates); # punt
401 if(grep /main/, @{$self->{packages}}) {
402 $self->{module} = 'main';
405 $self->{module} = $self->{packages}[0] || '';
410 $self->{version} = $self->{versions}{$self->{module}}
411 if defined( $self->{module} );
417 sub _do_find_module {
419 my $module = shift || croak 'find_module_by_name() requires a package name';
420 my $dirs = shift || \@INC;
422 my $file = File::Spec->catfile(split( /::/, $module));
423 foreach my $dir ( @$dirs ) {
424 my $testfile = File::Spec->catfile($dir, $file);
425 return [ File::Spec->rel2abs( $testfile ), $dir ]
426 if -e $testfile and !-d _; # For stuff like ExtUtils::xsubpp
427 return [ File::Spec->rel2abs( "$testfile.pm" ), $dir ]
428 if -e "$testfile.pm";
434 sub find_module_by_name {
435 my $found = shift()->_do_find_module(@_) or return;
440 sub find_module_dir_by_name {
441 my $found = shift()->_do_find_module(@_) or return;
446 # given a line of perl code, attempt to parse it if it looks like a
447 # $VERSION assignment, returning sigil, full name, & package name
448 sub _parse_version_expression {
452 my( $sig, $var, $pkg );
453 if ( $line =~ /$VERS_REGEXP/o ) {
454 ( $sig, $var, $pkg ) = $2 ? ( $1, $2, $3 ) : ( $4, $5, $6 );
456 $pkg = ($pkg eq '::') ? 'main' : $pkg;
461 return ( $sig, $var, $pkg );
467 my $filename = $self->{filename};
468 my $fh = IO::File->new( $filename )
469 or croak( "Can't open '$filename': $!" );
471 $self->_handle_bom($fh, $filename);
473 $self->_parse_fh($fh);
476 # Look for a UTF-8/UTF-16BE/UTF-16LE BOM at the beginning of the stream.
477 # If there's one, then skip it and set the :encoding layer appropriately.
479 my ($self, $fh, $filename) = @_;
481 my $pos = $fh->getpos;
482 return unless defined $pos;
485 my $count = $fh->read( $buf, length $buf );
486 return unless defined $count and $count >= 2;
489 if ( $buf eq "\x{FE}\x{FF}" ) {
490 $encoding = 'UTF-16BE';
491 } elsif ( $buf eq "\x{FF}\x{FE}" ) {
492 $encoding = 'UTF-16LE';
493 } elsif ( $buf eq "\x{EF}\x{BB}" ) {
495 $count = $fh->read( $buf, length $buf );
496 if ( defined $count and $count >= 1 and $buf eq "\x{BF}" ) {
501 if ( defined $encoding ) {
502 if ( "$]" >= 5.008 ) {
503 # $fh->binmode requires perl 5.10
504 binmode( $fh, ":encoding($encoding)" );
508 or croak( sprintf "Can't reset position to the top of '$filename'" );
515 my ($self, $fh) = @_;
517 my( $in_pod, $seen_end, $need_vers ) = ( 0, 0, 0 );
518 my( @pkgs, %vers, %pod, @pod );
524 while (defined( my $line = <$fh> )) {
529 # From toke.c : any line that begins by "=X", where X is an alphabetic
530 # character, introduces a POD segment.
532 if ( $line =~ /^=([a-zA-Z].*)/ ) {
534 # Then it goes back to Perl code for "=cutX" where X is a non-alphabetic
535 # character (which includes the newline, but here we chomped it away).
536 $is_cut = $cmd =~ /^cut(?:[^a-zA-Z]|$)/;
542 if ( $line =~ /^=head[1-4]\s+(.+)\s*$/ ) {
544 if ( $self->{collect_pod} && length( $pod_data ) ) {
545 $pod{$pod_sect} = $pod_data;
550 } elsif ( $self->{collect_pod} ) {
551 $pod_data .= "$line\n";
555 } elsif ( $is_cut ) {
557 if ( $self->{collect_pod} && length( $pod_data ) ) {
558 $pod{$pod_sect} = $pod_data;
568 # Skip comments in code
569 next if $line =~ /^\s*#/;
571 # Would be nice if we could also check $in_string or something too
572 if ($line eq '__END__') {
576 last if $line eq '__DATA__';
578 # parse $line to see if it's a $VERSION declaration
579 my( $vers_sig, $vers_fullname, $vers_pkg ) =
581 ? $self->_parse_version_expression( $line )
584 if ( $line =~ /$PKG_REGEXP/o ) {
586 push( @pkgs, $pkg ) unless grep( $pkg eq $_, @pkgs );
587 $vers{$pkg} = $2 unless exists( $vers{$pkg} );
588 $need_vers = defined $2 ? 0 : 1;
590 # VERSION defined with full package spec, i.e. $Module::VERSION
591 } elsif ( $vers_fullname && $vers_pkg ) {
592 push( @pkgs, $vers_pkg ) unless grep( $vers_pkg eq $_, @pkgs );
593 $need_vers = 0 if $vers_pkg eq $pkg;
595 unless ( defined $vers{$vers_pkg} && length $vers{$vers_pkg} ) {
597 $self->_evaluate_version_line( $vers_sig, $vers_fullname, $line );
600 # first non-comment line in undeclared package main is VERSION
601 } elsif ( !exists($vers{main}) && $pkg eq 'main' && $vers_fullname ) {
604 $self->_evaluate_version_line( $vers_sig, $vers_fullname, $line );
606 push( @pkgs, 'main' );
608 # first non-comment line in undeclared package defines package main
609 } elsif ( !exists($vers{main}) && $pkg eq 'main' && $line =~ /\w+/ ) {
612 push( @pkgs, 'main' );
614 # only keep if this is the first $VERSION seen
615 } elsif ( $vers_fullname && $need_vers ) {
618 $self->_evaluate_version_line( $vers_sig, $vers_fullname, $line );
621 unless ( defined $vers{$pkg} && length $vers{$pkg} ) {
631 if ( $self->{collect_pod} && length($pod_data) ) {
632 $pod{$pod_sect} = $pod_data;
635 $self->{versions} = \%vers;
636 $self->{packages} = \@pkgs;
637 $self->{pod} = \%pod;
638 $self->{pod_headings} = \@pod;
643 sub _evaluate_version_line {
645 my( $sigil, $var, $line ) = @_;
647 # Some of this code came from the ExtUtils:: hierarchy.
649 # We compile into $vsub because 'use version' would cause
650 # compiletime/runtime issues with local()
652 $pn++; # everybody gets their own package
653 my $eval = qq{BEGIN { my \$dummy = q# Hide from _packages_inside()
654 #; package Module::Metadata::_version::p$pn;
666 $eval = $1 if $eval =~ m{^(.+)}s;
669 # Try to get the $VERSION
671 # some modules say $VERSION = $Foo::Bar::VERSION, but Foo::Bar isn't
672 # installed, so we need to hunt in ./lib for it
673 if ( $@ =~ /Can't locate/ && -d 'lib' ) {
674 local @INC = ('lib',@INC);
677 warn "Error evaling version line '$eval' in $self->{filename}: $@\n"
679 (ref($vsub) eq 'CODE') or
680 croak "failed to build version sub for $self->{filename}";
681 my $result = eval { $vsub->() };
682 croak "Could not get version from $self->{filename} by executing:\n$eval\n\nThe fatal error was: $@\n"
685 # Upgrade it into a version object
686 my $version = eval { _dwim_version($result) };
688 croak "Version '$result' from $self->{filename} does not appear to be valid:\n$eval\n\nThe fatal error was: $@\n"
689 unless defined $version; # "0" is OK!
695 # Try to DWIM when things fail the lax version test in obvious ways
698 # Best case, it just works
699 sub { return shift },
701 # If we still don't have a version, try stripping any
702 # trailing junk that is prohibited by lax rules
705 $v =~ s{([0-9])[a-z-].*$}{$1}i; # 1.23-alpha or 1.23b
709 # Activestate apparently creates custom versions like '1.23_45_01', which
710 # cause version.pm to think it's an invalid alpha. So check for that
714 my $num_dots = () = $v =~ m{(\.)}g;
715 my $num_unders = () = $v =~ m{(_)}g;
716 my $leading_v = substr($v,0,1) eq 'v';
717 if ( ! $leading_v && $num_dots < 2 && $num_unders > 1 ) {
719 $num_unders = () = $v =~ m{(_)}g;
724 # Worst case, try numifying it like we would have before version objects
727 no warnings 'numeric';
734 my ($result) = shift;
736 return $result if ref($result) eq 'version';
738 my ($version, $error);
739 for my $f (@version_prep) {
740 $result = $f->($result);
741 $version = eval { version->new($result) };
742 $error ||= $@ if $@; # capture first failure
743 last if defined $version;
746 croak $error unless defined $version;
752 ############################################################
755 sub name { $_[0]->{module} }
757 sub filename { $_[0]->{filename} }
758 sub packages_inside { @{$_[0]->{packages}} }
759 sub pod_inside { @{$_[0]->{pod_headings}} }
760 sub contains_pod { 0+@{$_[0]->{pod_headings}} }
764 my $mod = shift || $self->{module};
766 if ( defined( $mod ) && length( $mod ) &&
767 exists( $self->{versions}{$mod} ) ) {
768 return $self->{versions}{$mod};
777 if ( defined( $sect ) && length( $sect ) &&
778 exists( $self->{pod}{$sect} ) ) {
779 return $self->{pod}{$sect};
789 Module::Metadata - Gather package and POD information from perl module files
793 use Module::Metadata;
795 # information about a .pm file
796 my $info = Module::Metadata->new_from_file( $file );
797 my $version = $info->version;
799 # CPAN META 'provides' field for .pm files in a directory
800 my $provides = Module::Metadata->provides(
801 dir => 'lib', version => 2
806 This module provides a standard way to gather metadata about a .pm file through
807 (mostly) static analysis and (some) code execution. When determining the
808 version of a module, the C<$VERSION> assignment is C<eval>ed, as is traditional
809 in the CPAN toolchain.
817 =item C<< new_from_file($filename, collect_pod => 1) >>
819 Constructs a C<Module::Metadata> object given the path to a file. Returns
820 undef if the filename does not exist.
822 C<collect_pod> is a optional boolean argument that determines whether POD
823 data is collected and stored for reference. POD data is not collected by
824 default. POD headings are always collected.
826 If the file begins by an UTF-8, UTF-16BE or UTF-16LE byte-order mark, then
827 it is skipped before processing, and the content of the file is also decoded
828 appropriately starting from perl 5.8.
830 =item C<< new_from_handle($handle, $filename, collect_pod => 1) >>
832 This works just like C<new_from_file>, except that a handle can be provided
833 as the first argument.
835 Note that there is no validation to confirm that the handle is a handle or
836 something that can act like one. Passing something that isn't a handle will
837 cause a exception when trying to read from it. The C<filename> argument is
838 mandatory or undef will be returned.
840 You are responsible for setting the decoding layers on C<$handle> if
843 =item C<< new_from_module($module, collect_pod => 1, inc => \@dirs) >>
845 Constructs a C<Module::Metadata> object given a module or package name.
846 Returns undef if the module cannot be found.
848 In addition to accepting the C<collect_pod> argument as described above,
849 this method accepts a C<inc> argument which is a reference to an array of
850 directories to search for the module. If none are given, the default is
853 If the file that contains the module begins by an UTF-8, UTF-16BE or
854 UTF-16LE byte-order mark, then it is skipped before processing, and the
855 content of the file is also decoded appropriately starting from perl 5.8.
857 =item C<< find_module_by_name($module, \@dirs) >>
859 Returns the path to a module given the module or package name. A list
860 of directories can be passed in as an optional parameter, otherwise
863 Can be called as either an object or a class method.
865 =item C<< find_module_dir_by_name($module, \@dirs) >>
867 Returns the entry in C<@dirs> (or C<@INC> by default) that contains
868 the module C<$module>. A list of directories can be passed in as an
869 optional parameter, otherwise @INC is searched.
871 Can be called as either an object or a class method.
873 =item C<< provides( %options ) >>
875 This is a convenience wrapper around C<package_versions_from_directory>
876 to generate a CPAN META C<provides> data structure. It takes key/value
877 pairs. Valid option keys include:
881 =item version B<(required)>
883 Specifies which version of the L<CPAN::Meta::Spec> should be used as
884 the format of the C<provides> output. Currently only '1.4' and '2'
885 are supported (and their format is identical). This may change in
886 the future as the definition of C<provides> changes.
888 The C<version> option is required. If it is omitted or if
889 an unsupported version is given, then C<provides> will throw an error.
893 Directory to search recursively for F<.pm> files. May not be specified with
898 Array reference of files to examine. May not be specified with C<dir>.
902 String to prepend to the C<file> field of the resulting output. This defaults
903 to F<lib>, which is the common case for most CPAN distributions with their
904 F<.pm> files in F<lib>. This option ensures the META information has the
905 correct relative path even when the C<dir> or C<files> arguments are
906 absolute or have relative paths from a location other than the distribution
911 For example, given C<dir> of 'lib' and C<prefix> of 'lib', the return value
912 is a hashref of the form:
917 file => 'lib/Package/Name.pm'
919 'OtherPackage::Name' => ...
922 =item C<< package_versions_from_directory($dir, \@files?) >>
924 Scans C<$dir> for .pm files (unless C<@files> is given, in which case looks
925 for those files in C<$dir> - and reads each file for packages and versions,
926 returning a hashref of the form:
931 file => 'Package/Name.pm'
933 'OtherPackage::Name' => ...
936 The C<DB> and C<main> packages are always omitted, as are any "private"
937 packages that have leading underscores in the namespace (e.g.
940 Note that the file path is relative to C<$dir> if that is specified.
941 This B<must not> be used directly for CPAN META C<provides>. See
942 the C<provides> method instead.
944 =item C<< log_info (internal) >>
946 Used internally to perform logging; imported from Log::Contextual if
947 Log::Contextual has already been loaded, otherwise simply calls warn.
951 =head2 Object methods
957 Returns the name of the package represented by this module. If there
958 are more than one packages, it makes a best guess based on the
959 filename. If it's a script (i.e. not a *.pm) the package name is
962 =item C<< version($package) >>
964 Returns the version as defined by the $VERSION variable for the
965 package as returned by the C<name> method if no arguments are
966 given. If given the name of a package it will attempt to return the
967 version of that package if it is specified in the file.
969 =item C<< filename() >>
971 Returns the absolute path to the file.
973 =item C<< packages_inside() >>
975 Returns a list of packages. Note: this is a raw list of packages
976 discovered (or assumed, in the case of C<main>). It is not
977 filtered for C<DB>, C<main> or private packages the way the
978 C<provides> method does. Invalid package names are not returned,
979 for example "Foo:Bar". Strange but valid package names are
980 returned, for example "Foo::Bar::", and are left up to the caller
983 =item C<< pod_inside() >>
985 Returns a list of POD sections.
987 =item C<< contains_pod() >>
989 Returns true if there is any POD in the file.
991 =item C<< pod($section) >>
993 Returns the POD data in the given section.
999 Original code from Module::Build::ModuleInfo by Ken Williams
1000 <kwilliams@cpan.org>, Randy W. Sims <RandyS@ThePierianSpring.org>
1002 Released as Module::Metadata by Matt S Trout (mst) <mst@shadowcat.co.uk> with
1003 assistance from David Golden (xdg) <dagolden@cpan.org>.
1005 =head1 COPYRIGHT & LICENSE
1007 Original code Copyright (c) 2001-2011 Ken Williams.
1008 Additional code Copyright (c) 2010-2011 Matt Trout and David Golden.
1009 All rights reserved.
1011 This library is free software; you can redistribute it and/or
1012 modify it under the same terms as Perl itself.