Linux Certif

Toute la documentation sur la certification Linux LPI

Text::Header.3pm

NAME

Text::Header - RFC 822/2068 "header" and "unheader" functions

SYNOPSIS

    use Text::Header;     # header and unheader exported
 
 

    # Construct headers similar to CGI.pm and HTTP::Headers
 
 

    @HEADERS = header(content_type => 'text/html',
                      author => 'Nathan Wiger',
                      last_modified => $date,
                      accept => [qw(text/html text/plain)]);
 
 

    # The above produces the array:
 
 

    @HEADERS = ("Content-Type: text/html\n",
                "Author: Nathan Wiger\n",
                "Last-Modified: Wed Sep 27 13:31:06 PDT 2000\n",
                "Accept: text/html, text/plain\n");
 
 

    # Can also construct SMTP headers to format mail
 
 

    @mail_headers = header(from => 'Nathan Wiger <nate@sun.com>',
                           to => 'perl5-porters@perl.org');
 
 

    print $MAIL @mail_headers, "\nKeep up the great work!\n";
 
 

    # The above would print this to the $MAIL handle:
 
 

    From: Nathan Wiger <nate@sun.com>
    To: perl5-porters@perl.org
 
 

    Keep up the great work!
 
 

DESCRIPTION

This module provides two new functions, "header" and "unheader", which provide general-purpose RFC 822 header construction and parsing. They do not provide any intelligent defaults of HTTP-specific methods. They are simply aimed at providing an easy means to address the mechanics of header parsing.

The output style is designed to mimic "CGI.pm" and "HTTP::Headers", so that users familiar with these interfaces will feel at home with these functions. As shown above, the "headers" function automatically does the following:

    1. uc's the first letter of each tag token and lc's the
       rest, also converting _'s to -'s automatically
 
 

    2. Adds a colon separating each tag and its value, and
       exactly one newline after each one
 
 

    3. Combines list elements into a comma-delimited
       string
 
 

Note that a list is always joined into a comma-delimited string. To insert multiple separate headers, simply call "header" with multiple args:

    push @out, header(accept => 'text/html',
                      accept => 'text/plain');
 
 

This would create multiple ``Accept:'' lines.

Note that unlike "CGI.pm", the "header" function provided here does not provide any intelligent defaults. If called as:

     @out_headers = header;
 
 

It will return an empty list. This allows "header" to be more general pupose, so it can provide SMTP and other headers as well. You can also use it as a generic text formatting tool, hence the reason it's under the "Text::" hierarchy.

The "unheader" function works in exactly the opposite direction from "header", pulling apart headers and returning a list. "unheader":

    1. lc's the entire tag name, converting -'s to _'s
 
 

    2. Separates each tag based on the colon delimiter,
       chomping newlines.
 
 

    3. Returns a list of tag/value pairs for easy assignment
       to a hash
 
 

So, assuming the @HEADERS array shown up top:

    %myheaders = unheader(@HEADERS);
 
 

The hash %myheaders would have the following values:

    %myheaders = (
        content_type => 'text/html',
        author => 'Nathan Wiger',
        last_modified => 'Wed Sep 27 13:31:06 PDT 2000',
        accept => 'text/html, text/plain'
    );
 
 

Note that all keys are converted to lowercase, and their values have their newlines stripped. However, note that comma-separated fields are not split up on input. This cannot be done reliably because some fields, such as the HTTP "Date:" header, can contain commas even though they are not lists. Inferring this type of structure would require knowledge of content, and these functions are specifically designed to be content-independent.

The "unheader" function will respect line wrapping, as seen in SMTP headers. It will simply join the lines and return the value, so that:

    %mail = unheader("To: Nathan Wiger <nate@sun.com>,
                              perl5-porters@perl.org");
 
 

Would return:

    $mail{to} = "Nathan Wiger <nate@sun.com>, perl5-porters@perl.org"
 
 

Notice that multiple spaces between the comma separator have been condensed to a single space. Since the "header" and "unheader" functions are direct inverses, this call:

    @out = header unheader @in;
 
 

Will result in @out being exactly equivalent to @in.

REFERENCES

This is designed as both a Perl 5 module and also a Perl 6 prototype. Please see the Perl 6 proposal at http://dev.perl.org/rfc/333.html

This module is designed to be fully compliant with the internet standards RFC 822 (SMTP Headers) and RFC 2068 (HTTP Headers).

AUTHOR

Copyright (c) 2000 Nathan Wiger <nate@sun.com>. All Rights Reserved.

This module is free software; you may copy this under the terms of the GNU General Public License, or the Artistic License, copies of which should have accompanied your Perl kit.