The second test you pose is probably the more efficient, but you overlook a few candidates:

    my $ref;
    if ($ref = ref($obj) and $ref !~ /^(SCALAR|ARRAY|HASH|GLOB|Regexp)
+$/) {
        $obj->method();
    }
[download]

Technically, the Regexp references are objects, but they are part of the core, and wouldn't represent an application-defined class. Of course, you can drop that from the regex above, if you like.

--rjray