NAME
Devel::Events::Filter::HandlerOptional - A role for filters that are useful even without a handler.
SYNOPSIS
package MyFilter;
use Moose;
with qw/Devel::Events::Filter::HandlerOptional/;
sub filter_event {
# do something
}
DESCRIPTION
This is just like Devel::Events::Filter except it won't complain if handler
is unset, but instead just drop events.