You can use ref to figure out the type of a reference/object. In your case, it seems you don't want to print it if it's "SCALAR"; or maybe the other way round, you do want to print it if it's "HTML::ElementTable::DataElement".

    if ( ref($row->[7]) eq "HTML::ElementTable::DataElement" )
    {
        print $row->[7]->as_text;
    }
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Update: a more generic way would be to use can() to directly test whether the method in question is available:

use Scalar::Util 'blessed';

    if ( blessed($row->[7]) and $row->[7]->can("as_text") )
    {
        print $row->[7]->as_text;
    }
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can() can only be called on blessed references, though, so you'd need to use Scalar::Util... (unless you resort to ugly stuff like if ("$ref"=~/=/ and ...) ).