GammaLib

We should think about supporting multiple extensions also. This is needed for the GCTAEventList class that writes two extensions into a FITS file (an event extension and a Good Time Interval extension).

A possible format for this could be:

test_cta_events1.fits[EVENTS2;GTI2]

test_cta_events1.fits[EVENTS2,1;GTI2,2]

If we decide to support this then GFitsExtension should be able to deal with an arbitrary number of extensions.

Note that instead of generally supporting this we could have two classes: GFitsExtension and GFitsExtensions. The second would be a container of GFitsExtension, but it would have a constructor that parses the multiple-extension string and creates instances of GFitsExtension.

Here a possible code simplification that should be reached with the GFitsExtension class. This code snipped is from GSkyMap::load:

    // If an extension name is specified then first try loading that
    // extension
    if (filename.has_extname()) {
        const GFitsHDU& hdu = *fits.at(filename.extname());
        if (is_healpix(hdu)) {
            read_healpix(static_cast<const GFitsTable&>(hdu));
            loaded = true;
        }
        else if (is_wcs(hdu)) {
            read_wcs(static_cast<const GFitsImage&>(hdu));
            loaded = true;
        }
    }

    // ... otherwise is an extension number is specified then try loading
    // the corresponding HDU
    else if (filename.has_extno()) {
        const GFitsHDU& hdu = *fits.at(filename.extno());
        if (is_healpix(hdu)) {
            read_healpix(static_cast<const GFitsTable&>(hdu));
            loaded = true;
        }
        else if (is_wcs(hdu)) {
            read_wcs(static_cast<const GFitsImage&>(hdu));
            loaded = true;
        }
    }

    if (filename.has_extension()) {
        const GFitsHDU& hdu = *fits.at(filename.extension());
        if (is_healpix(hdu)) {
            read_healpix(static_cast<const GFitsTable&>(hdu));
            loaded = true;
        }
        else if (is_wcs(hdu)) {
            read_wcs(static_cast<const GFitsImage&>(hdu));
            loaded = true;
        }
    }