package MyTst;
use warnings;
use strict;

our $Object;

sub import {
  my $class = shift;
  $Object   = shift;

  {
    no strict 'refs';
    *{caller().'::transaction'} = \&transaction;
  }
}

sub transaction(&) {
  $$Object->begin();
  shift()->();
  $$Object->end();
}

1;