use Tie::Constrained;

# Other code as before, with and without SIG{__DIE__}

sub db_connect
{
    my (
        $dsn,       # data source name
        $error_msg  # if any
        );

    # Set up connection string...
    $dsn = "DBI:mysql:database=xxx;host=somehost;port=nn";

    tie $cfg::dbh,
        'Tie::Constrained' =>
                    {
                    test => sub {
                                    $_[0]->isa('DBI::db')
                                    and $_[0]->ping;
                                },
                    value => DBI->connect($dsn,
                                          "user", "passwd",
#'DBI:mysql:','','',
                             {RaiseError => 0, AutoCommit => 1}),
                    fail => sub {
                                    $_[1] = DBI->connect($dsn,
                                                     "user", "passwd",
                                 {RaiseError => 0, AutoCommit => 1});
                            if( $DBI::errstr)
                            {
                                # FAIL
                                $error_msg = "db_connect(): $DBI::errstr";
                                print "$error_msg\n";
                                $cfg::db_retry_cnt++;
                                if( !$cfg::db_cxn_msg_sent &&
                                    $cfg::db_retry_cnt > 3 )
                                {
                                    print "would have sent email/sms\n";
                                    $cfg::db_cxn_msg_sent = 1;
                                }
                            }
                            else
                            {
                                # SUCCESS
                                $cfg::db_cxn_msg_sent = 0;
                                $cfg::db_retry_cnt = 0;
                            }
                                }
                    };
    $Tie::Constrained::STRICT = 1;
}