SYNOPSIS

 my $cleanup = $msg->rebuild;

DESCRIPTION

Modifying existing messages is a pain, certainly if this has to be done in an automated fashion. The problems are especially had when multiparts have to be created or removed. The rebuild() method tries to simplify this task and add some standard features.

DETAILS

Rebuilding a message

Modifying an existing message is a complicated job. Not only do you need to know what you are willing to change, but you have to take care about multiparts (possibly nested in multiple levels), rfc822 encapsulated messages, header field consistency, and so on. The rebuild() method let you focus on the task, and takes care of the rest.

The rebuild() method uses rules to transform the one message into an other. If one or more of the rules apply, a new message will be returned. A simple numeric comparison tells whether the message has changed. For example

 print "No change"
    if $message == $message->rebuild;

Transformation is made with a set of rules. Each rule performs only a small step, which makes is easily configurable. The rules are ordered, and when one makes a change to the result, the result will be passed to all the rules again until no rule makes a change on the part anymore. A rule may also return undef in which case the part will be removed from the (resulting) message.

General rules

This sections describes the general configuration rules: all quite straight forward transformations on the message structure. The rules marked with (*) are used by default.

You can specify a selection of these rules with rebuild(rules) and rebuild(extra_rules).

Conversion rules

This section describes the rules which try to be smart with the content. Please contribute with ideas and implementations.

Adding your own rules

If you have designed your own rule, please consider contributing this to Mail::Box; it may be useful for other people as well.

Each rule is called

 my $new = $code->($message, $part, %options)

where the %options are defined by the rebuild() method internals. At least the rules option is passed, which is a full expansion of all the rules which will be applied.

Your subroutine shall return $part if no changes are needed, undef if the part should be removed, and any newly constructed Mail::Message::Part when a change is required. It is easiest to start looking at the source code of this package, and copy from a comparible routine.

When you have your own routine, you simply call:

 my $rebuild_message = $message->rebuild
  ( extra_rules => [ \&my_own_rule, 'other_rule' ] );