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        next unless $class->isa('Class::Spiffy');
        my @export = grep {
            not defined &{"$caller_package\::$_"};
        } ( @{"$class\::EXPORT"}, 
            $args->{-base} ? @{"$class\::EXPORT_BASE"} : (),
          );
        my @export_ok = grep {
            not defined &{"$caller_package\::$_"};
        } @{"$class\::EXPORT_OK"};

        # Avoid calling the expensive Exporter::export 
        # if there is nothing to do (optimization)
        my %exportable = map { ($_, 1) } @export, @export_ok;
        next unless keys %exportable;

        my @export_save = @{"$class\::EXPORT"};
        my @export_ok_save = @{"$class\::EXPORT_OK"};
        @{"$class\::EXPORT"} = @export;
        @{"$class\::EXPORT_OK"} = @export_ok;
        my @list = grep {
            (my $v = $_) =~ s/^[\!\:]//;
            $exportable{$v} or ${"$class\::EXPORT_TAGS"}{$v};
        } @export_list;
        Exporter::export($class, $caller_package, @list);
        @{"$class\::EXPORT"} = @export_save;
        @{"$class\::EXPORT_OK"} = @export_ok_save;
    }
}

sub base {
    push @_, -base;
    goto &import;
}

sub all_my_bases {
    my $class = shift;

    return $bases_map->{$class} 
      if defined $bases_map->{$class};

    my @bases = ($class);
    no strict 'refs';
    for my $base_class (@{"${class}::ISA"}) {
        push @bases, @{all_my_bases($base_class)};
    }
    my $used = {};
    $bases_map->{$class} = [grep {not $used->{$_}++} @bases];
}

my %code = (
    sub_start =>
      "sub {\n",
    set_default =>
      "  \$_[0]->{%s} = %s\n    unless exists \$_[0]->{%s};\n",
    init =>
      "  return \$_[0]->{%s} = do { my \$self = \$_[0]; %s }\n" .
      "    unless \$#_ > 0 or defined \$_[0]->{%s};\n",
    weak_init =>
      "  return do {\n" .
      "    \$_[0]->{%s} = do { my \$self = \$_[0]; %s };\n" .
      "    Scalar::Util::weaken(\$_[0]->{%s}) if ref \$_[0]->{%s};\n" .
      "    \$_[0]->{%s};\n" .
      "  } unless \$#_ > 0 or defined \$_[0]->{%s};\n",
    return_if_get =>
      "  return \$_[0]->{%s} unless \$#_ > 0;\n",
    set =>
      "  \$_[0]->{%s} = \$_[1];\n",
    weaken =>
      "  Scalar::Util::weaken(\$_[0]->{%s}) if ref \$_[0]->{%s};\n",
    sub_end =>
      "  return \$_[0]->{%s};\n}\n",
);

sub field {
    my $package = caller;
    my ($args, @values) = do {
        no warnings;
        local *boolean_arguments = sub { (qw(-weak)) };
        local *paired_arguments = sub { (qw(-package -init)) };
        Class::Spiffy->parse_arguments(@_);
    };
    my ($field, $default) = @values;
    $package = $args->{-package} if defined $args->{-package};
    die "Cannot have a default for a weakened field ($field)"
        if defined $default && $args->{-weak};
    return if defined &{"${package}::$field"};
    require Scalar::Util if $args->{-weak};
    my $default_string =
        ( ref($default) eq 'ARRAY' and not @$default )
        ? '[]'
        : (ref($default) eq 'HASH' and not keys %$default )
          ? '{}'
          : default_as_code($default);

    my $code = $code{sub_start};
    if ($args->{-init}) {
        my $fragment = $args->{-weak} ? $code{weak_init} : $code{init};
        $code .= sprintf $fragment, $field, $args->{-init}, ($field) x 4;
    }
    $code .= sprintf $code{set_default}, $field, $default_string, $field
      if defined $default;
    $code .= sprintf $code{return_if_get}, $field;
    $code .= sprintf $code{set}, $field;
    $code .= sprintf $code{weaken}, $field, $field 
      if $args->{-weak};
    $code .= sprintf $code{sub_end}, $field;

    my $sub = eval $code;
    die $@ if $@;
    no strict 'refs';
    *{"${package}::$field"} = $sub;
    return $code if defined wantarray;
}

sub default_as_code {
    require Data::Dumper;
    local $Data::Dumper::Sortkeys = 1;
    my $code = Data::Dumper::Dumper(shift);
    $code =~ s/^\$VAR1 = //;
    $code =~ s/;$//;
    return $code;
}

sub const {
    my $package = caller;
    my ($args, @values) = do {
        no warnings;
        local *paired_arguments = sub { (qw(-package)) };
        Class::Spiffy->parse_arguments(@_);
    };
    my ($field, $default) = @values;
    $package = $args->{-package} if defined $args->{-package};
    no strict 'refs';
    return if defined &{"${package}::$field"};
    *{"${package}::$field"} = sub { $default }
}

sub stub {
    my $package = caller;
    my ($args, @values) = do {
        no warnings;
        local *paired_arguments = sub { (qw(-package)) };
        Class::Spiffy->parse_arguments(@_);
    };
    my ($field, $default) = @values;
    $package = $args->{-package} if defined $args->{-package};
    no strict 'refs';
    return if defined &{"${package}::$field"};
    *{"${package}::$field"} = 
    sub { 
        require Carp;
        Carp::confess 
          "Method $field in package $package must be subclassed";
    }
}

sub parse_arguments {
    my $class = shift;
    my ($args, @values) = ({}, ());
    my %booleans = map { ($_, 1) } $class->boolean_arguments;
    my %pairs = map { ($_, 1) } $class->paired_arguments;
    while (@_) {
        my $elem = shift;
        if (defined $elem and defined $booleans{$elem}) {