/ 
Blosxom-Header-0.01010
/ Blosxom::Header

NAME

Blosxom::Header - Missing interface to modify HTTP headers

SYNOPSIS

use Blosxom::Header;

my $headers = { -type => 'text/html' };

my $h = Blosxom::Header->new($headers);
my $value = $h->get($key);
my $bool = $h->exists($key);

$h->set($key, $value); # overwrites existent header
$h->remove($key);

$h->{headers}; # same reference as $headers

DESCRIPTION

Blosxom, a weblog application, exports a global variable $header which is a reference to hash. This application passes $header CGI::header() to generate HTTP headers.

When plugin writers modify HTTP headers, they must write as follows:

package foo;
$blosxom::header->{'-type'} = 'text/plain';

It's obviously bad practice. Blosxom misses the interface to modify them.

This module allows you to modify them in an object-oriented way. If loaded, you might write as follows:

my $h = Blosxom::Header->new($blosxom::header);
$h->set('Content-Type' => 'text/plain');

METHODS

$h = Blosxom::Header->new($headers);

Creates a new Blosxom::Header object. The object holds a reference to the original given $headers argument.

$h->get('foo')

Returns a value of the specified HTTP header.

$h->exists('foo')

Returns a Boolean value telling whether the specified HTTP header exists.

$h->set('foo' => 'bar')

Sets a value of the specified HTTP header.

$h->remove('foo')

Deletes the specified element from HTTP headers.

EXAMPLES

The following code is a Blosxom plugin to enable conditional GET and HEAD using If-None-Match and If-Modified-Since headers. Refer to Plack::Middleware::ConditionalGET.

plugins/conditional_get:

package conditional_get;
use strict;
use warnings;
use Blosxom::Header;

sub start { !$blosxom::static_entries }

sub last {
    return unless $ENV{REQUEST_METHOD} =~ /^(GET|HEAD)$/;

    my $h = Blosxom::Header->new($blosxom::header);
    if (_etag_matches($h) or _not_modified_since($h)) {
        $h->set('Status' => '304 Not Modified');
        $h->remove($_)
            for qw(Content-Type Content-Length Content-Disposition);

        # Truncate output
        $blosxom::output = q{};
    }

    return;
}

sub _etag_matches {
    my $h = shift;
    return unless $h->exists('ETag');
    $h->get('ETag') eq _value($ENV{HTTP_IF_NONE_MATCH});
}

sub _not_modified_since {
    my $h = shift;
    return unless $h->exists('Last-Modified');
    $h->exists('Last-Modified') eq _value($ENV{HTTP_IF_MODIFIED_SINCE});
}

sub _value {
    my $str = shift;
    $str =~ s{;.*$}{};
    $str;
}

1;

DEPENDENCIES

Blosxom 2.1.2

SEE ALSO

The interface of this module is inspired by Plack::Util::headers.

AUTHOR

Ryo Anazawa (anazawa@cpan.org)

LICENSE AND COPYRIGHT

Copyright (c) 2011 Ryo Anazawa. All rights reserved.

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

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.