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=head1 NAME

Module::Build::Notes - Create persistent distribution configuration modules

=head1 DESCRIPTION

This module is used internally by Module::Build to create persistent
configuration files that can be installed with a distribution.  See
L<Module::Build::ConfigData> for an example.

=head1 AUTHOR

Ken Williams <kwilliams@cpan.org>

=head1 COPYRIGHT

Copyright (c) 2001-2006 Ken Williams.  All rights reserved.

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

=head1 SEE ALSO

perl(1), L<Module::Build>(3)

=cut

__DATA__
package NOTES_NAME;
use strict;
my $arrayref = eval do {local $/; <DATA>}
  or die "Couldn't load ConfigData data: $@";
close DATA;
my ($config, $features, $auto_features) = @$arrayref;

sub config { $config->{$_[1]} }

sub set_config { $config->{$_[1]} = $_[2] }
sub set_feature { $features->{$_[1]} = 0+!!$_[2] }  # Constrain to 1 or 0

sub auto_feature_names { grep !exists $features->{$_}, keys %$auto_features }

sub feature_names {
  my @features = (keys %$features, auto_feature_names());
  @features;
}

sub config_names  { keys %$config }

sub write {
  my $me = __FILE__;
  require IO::File;

  # Can't use Module::Build::Dumper here because M::B is only a
  # build-time prereq of this module
  require Data::Dumper;

  my $mode_orig = (stat $me)[2] & 07777;
  chmod($mode_orig | 0222, $me); # Make it writeable
  my $fh = IO::File->new($me, 'r+') or die "Can't rewrite $me: $!";
  seek($fh, 0, 0);
  while (<$fh>) {
    last if /^__DATA__$/;
  }
  die "Couldn't find __DATA__ token in $me" if eof($fh);

  seek($fh, tell($fh), 0);
  my $data = [$config, $features, $auto_features];
  $fh->print( 'do{ my '
	      . Data::Dumper->new([$data],['x'])->Purity(1)->Dump()
	      . '$x; }' );
  truncate($fh, tell($fh));
  $fh->close;

  chmod($mode_orig, $me)
    or warn "Couldn't restore permissions on $me: $!";
}

sub feature {
  my ($package, $key) = @_;
  return $features->{$key} if exists $features->{$key};

  my $info = $auto_features->{$key} or return 0;

  # Under perl 5.005, each(%$foo) isn't working correctly when $foo
  # was reanimated with Data::Dumper and eval().  Not sure why, but
  # copying to a new hash seems to solve it.
  my %info = %$info;

  require Module::Build;  # XXX should get rid of this
  while (my ($type, $prereqs) = each %info) {
    next if $type eq 'description' || $type eq 'recommends';

    my %p = %$prereqs;  # Ditto here.
    while (my ($modname, $spec) = each %p) {
      my $status = Module::Build->check_installed_status($modname, $spec);
      if ((!$status->{ok}) xor ($type =~ /conflicts$/)) { return 0; }
      if ( ! eval "require $modname; 1" ) { return 0; }
    }
  }
  return 1;
}

=begin private

=head1 NAME

NOTES_NAME - Configuration for MODULE_NAME

=head1 SYNOPSIS

  use NOTES_NAME;
  $value = NOTES_NAME->config('foo');
  $value = NOTES_NAME->feature('bar');

  @names = NOTES_NAME->config_names;
  @names = NOTES_NAME->feature_names;

  NOTES_NAME->set_config(foo => $new_value);
  NOTES_NAME->set_feature(bar => $new_value);
  NOTES_NAME->write;  # Save changes


=head1 DESCRIPTION

This module holds the configuration data for the C<MODULE_NAME>
module.  It also provides a programmatic interface for getting or
setting that configuration data.  Note that in order to actually make
changes, you'll have to have write access to the C<NOTES_NAME>
module, and you should attempt to understand the repercussions of your
actions.


=head1 METHODS