Mail::Message::Head::Subset - subset of header information of a message

Description

       Some types of folders contain an index file which lists a few lines of information per messages.
       Especially when it is costly to read header lines, the index speeds-up access considerably.  For
       instance, the subjects of all messages are often wanted, but waiting for a thousand messages of the
       folder to be read may imply a thousand network reads (IMAP) or file openings (MH)

       When you access header fields which are not in the header subset, the whole header has to be parsed
       (which may consume considerable time, depending on the type of folder).

       Extends "DESCRIPTION" in Mail::Message::Head.

Details

       Extends "DETAILS" in Mail::Message::Head.

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.

Inheritance

        Mail::Message::Head::Subset realizes a Mail::Message::Head::Complete

        Mail::Message::Head::Subset
          is a Mail::Message::Head
          is a Mail::Reporter

License

       Copyrights 2001-2025 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/

perl v5.40.1                                       2025-04-25                   Mail::Message::Head::Subset(3pm)

Methods

       Extends "METHODS" in Mail::Message::Head.

   Constructors
       Extends "Constructors" in Mail::Message::Head.

       Mail::Message::Head::Subset->build( [PAIR|$field]-LIST )
           Inherited, see "Constructors" in Mail::Message::Head

       Mail::Message::Head::Subset->new(%options)
           Inherited, see "Constructors" in Mail::Message::Head

   Theheader
       Extends "The header" in Mail::Message::Head.

       $obj->isDelayed()
           Inherited, see "The header" in Mail::Message::Head

       $obj->isEmpty()
           Inherited, see "The header" in Mail::Message::Head

       $obj->isModified()
           Inherited, see "The header" in Mail::Message::Head

       $obj->knownNames()
           Inherited, see "The header" in Mail::Message::Head

       $obj->message( [$message] )
           Inherited, see "The header" in Mail::Message::Head

       $obj->modified( [BOOLEAN] )
           Inherited, see "The header" in Mail::Message::Head

       $obj->orderedFields()
           Inherited, see "The header" in Mail::Message::Head

   Accesstotheheader
       Extends "Access to the header" in Mail::Message::Head.

       $obj->count($name)
           Count  the  number  of  fields  with  this  $name.  If the $name cannot be found, the full header get
           loaded.  In case we find any $name field, it is decided we know all  of  them,  and  loading  is  not
           needed.

       $obj->get( $name, [$index] )
           Get  the data which is related to the field with the $name.  The case of the characters in $name does
           not matter.  When a $name is used which is not known yet, realization will take place.

       $obj->study( $name, [$index] )
           Inherited, see "Access to the header" in Mail::Message::Head

   Aboutthebody
       Extends "About the body" in Mail::Message::Head.

       $obj->guessBodySize()
           The body size is defined in the "Content-Length" field.  However, this field may not  be  known.   In
           that  case, a guess is made based on the known "Lines" field.  When also that field is not known yet,
           "undef" is returned.

       $obj->isMultipart()
           Inherited, see "About the body" in Mail::Message::Head

   Internals
       Extends "Internals" in Mail::Message::Head.

       $obj->addNoRealize($field)
           Inherited, see "Internals" in Mail::Message::Head

       $obj->addOrderedFields($fields)
           Inherited, see "Internals" in Mail::Message::Head

       $obj->fileLocation()
           Inherited, see "Internals" in Mail::Message::Head

       $obj->load()
           Inherited, see "Internals" in Mail::Message::Head

       $obj->moveLocation($distance)
           Inherited, see "Internals" in Mail::Message::Head

       $obj->read($parser)
           Inherited, see "Internals" in Mail::Message::Head

       $obj->setNoRealize($field)
           Inherited, see "Internals" in Mail::Message::Head

   Errorhandling
       Extends "Error handling" in Mail::Message::Head.

       $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, $callback] )
       Mail::Message::Head::Subset->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )
           Inherited, see "Error handling" in Mail::Reporter

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

       $obj->log( [$level, [$strings]] )
       Mail::Message::Head::Subset->log( [$level, [$strings]] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->logPriority($level)
       Mail::Message::Head::Subset->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::Message::Head.

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

Name

       Mail::Message::Head::Subset - subset of header information of a message

Overloaded

       Extends "OVERLOADED" in Mail::Message::Head.

       overload: ""
           Inherited, see "OVERLOADED" in Mail::Message::Head

       overload: bool
           Inherited, see "OVERLOADED" in Mail::Message::Head

Synopsis

        my $subset = Mail::Message::Head::Subset->new(...)
        $subset->isa('Mail::Message::Head')  # true
        $subset->guessBodySize               # integer or undef
        $subset->isDelayed                   # true