# 1) subclassing

package Foo::Bar::Sub;
use base 'Foo::Bar';

sub begin_work { shift->try_it }
sub commit     { shift->do_it }
sub begin_work { shift->try_it }

# 2) wrapping

package Foo::Bar::Wrap;
use Attribute::Property;
use Scalar::Util qw(blessed)

sub new    : New;
sub object : Property { blessed }

sub begin_work { shift->object->try_it }
sub commit     { shift->object->do_it }
sub rollback   { shift->object->fallback }

# 3) intruding

sub Foo::Bar::begin_work { shift->try_it }
sub Foo::Bar::commit     { shift->do_it }
sub Foo::Bar::rollback   { shift->fallback }