On Thu, Nov 29, 2012 at 11:34 AM, Martin Desruisseaux < [email protected]> wrote:
> In Java, we can not really express "nil value" by null, because "nil > value" are not completely nil... They may still be associated to XLink or > the above-cited NilReason. So the proposed approach, which was implemented > in Geotk, is to still return an instance of the metadata object, but the > instance additionally implements the NilObject marker interface - meaning > "I'm totally empty from an ISO 19115 point of view - but I may still have > some ISO 19139 attributes, in particular a NilReason attribute" (sorry for > the headache... The OGC/ISO standards are very complex...). The above-cited > javadoc contains an example of what it looks like in XML. > > Is there any comment about this approach? I think this looks like a good approach. On first glance I wondered if using some kind of enum or constant would be preferable, but it sounds like a marker interface is more flexible. It gives you the flexibility to include the other attributes you were referring to. Greg
