FWIW, I would write this code:

  $shift->caption($args->{'caption'});
  $shift->starts($args->{'starts'});
  $shift->ends($args->{'ends'});
  $shift->monday($args->{'monday'});
  $shift->tuesday($args->{'tuesday'});
  $shift->wednesday($args->{'wednesday'});
  $shift->thursday($args->{'thursday'});
  $shift->friday($args->{'friday'});
  $shift->saturday($args->{'saturday'});
  $shift->sunday($args->{'sunday'});
  $shift->holiday($args->{'holiday'});
[download]

as:

$shift->$_( $args->{$_} ) foreach qw(
 caption
 starts
 ends
 monday
 tuesday
 wednesday
 thursday
 friday
 saturday
 sunday
 holiday
);
[download]

You're specifying things twice (name of method and name of field in hash), which is always bad from a maintenance point of view.

Also, I find the use of $shift confusing: usually a variable called $self is a more common idiom.

Liz