if ( ref( $obj ) eq 'Foo::Bar' ) {
    # This is generally wrong
}

use Scalar::Util 'blessed';
if ( blessed( $obj ) and $obj->can( $some_method ) ) {
    # We asked if the object could do something. We win. OO inheritance was respected and we played by the rules.
}

if ( blessed( $obj ) and $obj->isa( 'Some::Object' ) ) {
    # This is close to your original and is slightly deprecated but also respects OO inheritance.
}