columns readCategory readColumn readColumnCount readRowCount writeColumn ~BintableHdu

readCategory() HduCategory readCategory ( ) const overridevirtual Read the category of the HDU. This is more specific than the type of the HDU. The category is a bitmask which encodes more properties, e.g. Primary is more specific than Image, and MetadataPrimary is even more specific. The result of this function should not be tested with operator ==, but rather with HduFilter::accepts(). Often, the method matches can be used directly. This is indeed a read operation, because the header should be parsed, e.g. to know whether the data unit is empty or not. See also HduCategory matches Reimplemented from Hdu.