yes...yes...but, what if i want to:

my $dbh = "123456"; # just as a test, instead of DBI->connect(....);

if ($dbh != valid_DBI_handle()) {
  print "please supply a PROPER reference to a DBI object, or whatever
+ it's called\n";
} else {
  # okay, dbh actually points to a real db connection
  print "dbh is truly valid";
}
[download]

because most posts about this say to simply

if (!$dbh) {
  die "no db connection!";
} else {
  $dbh->run_some_command();
}
[download]

well, if $dbh eq 1, then we try to run_some_command will fail, and cause a bad user experience, to the point where the user's trust in the site dies along with the script!