NAME

       Mail::Box::MH::Index - keep index files for messages.

INHERITANCE

        Mail::Box::MH::Index
          is a Mail::Reporter

SYNOPSIS

        my $index = Mail::Box::MH::Index->new;
        $index->read(...)
        $index->write(...)

DESCRIPTION

       Message folders which store their data in one single file per message are very inefficient for producing
       subject overviews and for computing message threads.  The "Mail::Box::MH::Index" object is able to store
       and read a the headers of a set of "Mail::Box::MH::Message" messages which are part of a single
       "Mail::Box::MH" folder in one file.

       When the "Mail::Box::MH::Index" functionality is enabled by specifying Mail::Box::MH::new(keep_index)
       when opening a folder, the index file is automatically read.  When the folder is closed, a new index file
       is created.

       Special care is taken to avoid problems which occur when the user changes or removes message files
       without updating the index. If the index is not trustworthy it will not be used (costing some performance
       for the reader of the folder).

       Extends "DESCRIPTION" in Mail::Reporter.

METHODS

       Extends "METHODS" in Mail::Reporter.

   Constructors
       Extends "Constructors" in Mail::Reporter.

       Mail::Box::MH::Index->new(%options)
            -Option   --Defined in     --Default
             filename                    <required>
             head_type                   Mail::Message::Head::Subset
             head_wrap                   72
             log        Mail::Reporter   'WARNINGS'
             trace      Mail::Reporter   'WARNINGS'

           filename => FILENAME
             The FILENAME which is used to store the headers of all the e-mails for one folder. This must be an
             absolute pathname.

           head_type => CLASS
             The type of headers which will be used to store header information when it is read from the index
             file.  You can not be sure the index contains all header line (the mailbox may have been updated
             without updating the index) so this will usually be (an sub-class of) Mail::Message::Head::Subset.

           head_wrap => INTEGER
             The preferred number of character in each header line.

           log => LEVEL
           trace => LEVEL

   The Index
       $obj->append($messages)
           Append $messages to the index file.

       $obj->filename()
           Returns the name of the index file.

       $obj->get($msgfile)
           Look if there is header info for the specified $msgfile.  The filename represents one message in
           folder type which are organized as directory.  This method will return an object of the
           new(head_type) as specified during creation of the index object, or "undef" if the information is not
           known or not trustworthy -i.e. the file size changed.

       $obj->read()
           Read the index file.  The header objects can after this be requested with the get() method.

       $obj->write($messages)
           Write an index file containing the headers specified $messages (Mail::Message objects).

   Error handling
       Extends "Error handling" in Mail::Reporter.

       $obj->AUTOLOAD()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->addReport($object)
           Inherited, see "Error handling" in Mail::Reporter

       $obj->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )
       Mail::Box::MH::Index->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->errors()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->log( [$level, [$strings]] )
       Mail::Box::MH::Index->log( [$level, [$strings]] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->logPriority($level)
       Mail::Box::MH::Index->logPriority($level)
           Inherited, see "Error handling" in Mail::Reporter

       $obj->logSettings()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->notImplemented()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->report( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->reportAll( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->trace( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->warnings()
           Inherited, see "Error handling" in Mail::Reporter

   Cleanup
       Extends "Cleanup" in Mail::Reporter.

       $obj->DESTROY()
           Inherited, see "Cleanup" in Mail::Reporter

DIAGNOSTICS

       Error: Package $package does not implement $method.
           Fatal error: the specific package (or one of its superclasses) does not implement this method where
           it should. This message means that some other related classes do implement this method however the
           class at hand does not.  Probably you should investigate this and probably inform the author of the
           package.

SEE ALSO

       This module is part of Mail-Box distribution version 3.004, built on December 22, 2017.

       Do not forget to read Mail::Box-Overview, Mail::Box-Cookbook, and Mail::Box-Index.  Examples are included
       in the Mail-Box distribution, directories 'examples' and 'scripts'.

       Browseable manuals, papers, and other released material van be found at  Website:
       http://perl.overmeer.net/mailbox/

       The central modules (in separate distributions) in the MailBox suite are: Mail::Message, Mail::Box,
       Mail::Box::IMAP4, Mail::Box::POP3, Mail::Box::Parser::C, Mail::Box::Dbx (unpublished), Mail::Transport,
       Object::Realize::Later, and User::Identity.

       Please post questions or ideas to the author markov@cpan.org.

LICENSE

       Copyrights 2001-2017 by [Mark Overmeer]. For other contributors see ChangeLog.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.  See http://dev.perl.org/licenses/