DB<4> c
DBD::DB2::Constants::AUTOLOAD(blib\lib/DBD/DB2/Constants.pm:1572):
1572:       my $val = constant($constname, @_ ? $_[0] : 0);

  DB<4> p $constname
SQL_PARAM_INPUT_OUTPUT

  DB<5> l
1572==>b            my $val = constant($constname, @_ ? $_[0] : 0);
1573:       if ($! != 0) {
1574:           if ($! =~ /Invalid/) {
1575:               $AutoLoader::AUTOLOAD = $AUTOLOAD;
1576:               goto &AutoLoader::AUTOLOAD;
1577            }
1578            else {
1579:                   croak "Your vendor has not defined DBD::DB2::Constants macro $constname";
1580            }
1581        }
  DB<5> n
constant 'SQL_PARAM_INPUT_OUTPUT',0
Now I'm here and return 2
DBD::DB2::Constants::AUTOLOAD(blib\lib/DBD/DB2/Constants.pm:1573):
1573:       if ($! != 0) {

  DB<5> p $!
No such file or directory

  DB<6> p $val
2

  DB<7>