transform OO interface into functional one

gistfile1.pl

# $value = get_header( $blosxom::header, 'foo' );
# $bool  = exists_header( $blosxom::header, 'foo' );
# set_header( $blosxom::header, 'foo' => 'bar' );
# remove_header( $blosxom::header, 'foo' );

for my $method ( qw(get set remove exists) ) {
    my $slot = __PACKAGE__ . "::${method}_header";
    my $code = sub {
        my ( $header_ref, @args ) = @_;
        __PACKAGE__->new( $heaeder_ref )->$method( @args );
    };

    no strict 'refs';
    *$slot = $code;
}

# 逆

for my $method ( qw(get set remove exists) ) {
    my $slot     = __PACKAGE__ . "::$method";
    my $func_ref = \&{ "${slot}_header" };
    my $sub_ref  = sub {
        my ( $self, @args ) = @_;
        return $func_ref->( $heaeder_ref, @args );
    };

    no strict 'refs';
    *$slot = $sub_ref;
}