$m

• Saw it with autohandlers (call_next()) and caching (cache(), cache_self()).
• It's the Mason Request object.
• Has a bunch of handy methods, particularly for calling other components.
• It's a global available in all components, all the time.
• Methods include:
• scomp() - returns component output in a scalar

my $link =
    $m->scomp( '/lib/link_to_person.mas',
               person => $person );

• abort() - stops processing, in its tracks!

$m->abort unless $user->is_editor;

• ... and many more.