/ 
Blosxom-Header-0.01012
/ Blosxom::Header

NAME

Blosxom::Header - Missing interface to modify HTTP headers

SYNOPSIS

# blosxom.cgi
package blosxom;

our $header = { -type => 'text/html' };

# plugins/foo
package foo;
use Blosxom::Header;

my $h = Blosxom::Header->new($blosxom::header);
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 $blosxom::header

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 developers modify HTTP headers, they must write as follows:

package foo;
$blosxom::header->{'-status'} = '304 Not Modified';

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

This module allows you to modify them in an object-oriented way:

my $h = Blosxom::Header->new($blosxom::header);
$h->set(Status => '304 Not Modified');

You don't have to care whether to put a hyphen before a key, and also whether to make a key lowercased or camelized. And so the following forms are semantically identical:

status
-status
Status
-Status

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.

RECOGNIZED PARAMETERS

Refer to CGI::header.

type

Represents the Content-Type header.

$h->set(type => 'text/plain')
nph

If set to a true value, will issue the correct headers to work with a NPH (no-parse-header) script.

$h->set(nph => 1)
expires

Represents the Expires header. You can specify an absolute or relative expiration interval. The following forms are all valid for this field.

$h->set(expires => '+30s') # 30 seconds from now
$h->set(expires => '+10m') # ten minutes from now
$h->set(expires => '+1h')  # one hour from now
$h->set(expires => '-1d')  # yesterday
$h->set(expires => 'now')  # immediately
$h->set(expires => '+3M')  # in three months
$h->set(expires => '+10y') # in ten years time

# at the indicated time & date
$h->set(expires => 'Thu, 25 Apr 1999 00:40:33 GMT')

Represents the Set-Cookie header. The parameter can be an arrayref or a string.

$h->set(cookie => ['foo=bar', 'bar=baz']);
$h->set(cookie => 'foo=bar')
charset

Represents the character set sent to the browser. If not provided, defaults to ISO-8859-1.

$h->set(charset => 'utf-8')
attachment

Can be used to turn the page into an attachment. Represents suggested name for the saved file.

$h->set(attachment => 'foo.png')
p3p

Will add a P3P tag to the outgoing header. The parameter can be arrayref or a space-delimited string.

$h->set(p3p => [qw(CAO DSP LAW CURa)])
$h->set(p3p => 'CAO DSP LAW CURa')

In either case, the outgoing header will be formatted as:

P3P: policyref="/w3c/p3p.xml" cp="CAO DSP LAW CURa"

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-Length attachment);

        # If the Content-Type header isn't defined,
        # CGI::header will add default value.
        # And so makes it defined.
        $h->set(type => q{});

        # 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');
    $h->get('Last-Modified') eq _value($ENV{HTTP_IF_MODIFIED_SINCE});
}

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

1;

DEPENDENCIES

Blosxom 2.1.2

SEE ALSO

CGI

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.