Re: [Geotools-devel] First draft of org.geotools.factory.Hints

[Martin D. <mar...@no...>]

Jody Garnett a =E9crit :
> Thanks Martin! That is great, did we want to do this work together on a=
=20
> branch?

Yes. I haven't done any work yet except this Hints class, because it was=20
already used by GridCoverage anyway and I was working yesterday on the=20
part that uses it (namely Resampler2D, the class that reproject images).=20
I have been silent on the Factory topic lately because I wanted to think=20
a little bit more about it. I started to see yesterday a possible plan=20
for Hints in CRS. Since it would not break compatibility and would not=20
really be a major shift, we may or may not do it on a branch, at our choi=
ce.

Lets try some clarifications first (please correct me if I'm=20
understanding wrong):

   - If I'm understanding right, you wish the ability to provides hints
     an a call basis (so two threads can have independant set of hints).

   - Hints, if provided, would have priority over any 'setOrdering'
     settings.

   - In my opinion, Hints doesn't invalidate the need for a default
     ordering. If no hints are provided, some default ordering applies.
     For example, I still believe that unless otherwise specified by a
     hint, a database-backed EPSG factory should have priority over a
     WKT-based one if the JDBC connection is found available.

   - For default ordering, I suggest that system-wide setting is
     suffisient.

   - Since hints are unrelated to ordering (they have priority over
     any ordering settings), there is no need for FOO_ORDERING hint.
     User can specifies directly the factory he wants to use as a
     FOO_FACTORY hint.

   - The hint can be either an instance of a factory, or a
     java.lang.Class if the user just wants to specify the implementation
     but don't care much about which instance of this implementation is
     used (it gives a chances to FactoryFinder to share the same
     instance of that particular implementation).


	Does it make sense?

		Martin.