[EMAIL PROTECTED] a écrit :
> The reader would check if a hint was provided in the constructor,
> otherwise it will fall back on the system hint, and if that one is not
> defined either, assume a default behaviour.
>
> We are wondering if this follows the "best practices" on how to use hints
> in GeoTools.
Yes with a slight nuance. If we want to apply the same approach than referencing
(for example) then:
- The constructor do not looks for system hint. It uses user-provided hints
exactly as provided, and assume default behavior for non-specified hints.
- The System hints are added by the FactoryFinder.
Example:
The DefaultCoordinateOperationFactory constructor looks for
Hints.LENIENT_DATUM_SHIFT as specified in the user-provided Hints. If the user
didn't privided a value for this hints, then the factory default to
Boolean.FALSE. It does *not* looks into the system hints - it uses the hints
exactly as specified by the users.
public DefaultCoordinateOperationFactory(Hints userHints) {
super(userHints);
boolean lenientDatumShift = false;
if (userHints != null) {
Object candidate = userHints.get(Hints.LENIENT_DATUM_SHIFT);
if (candidate instanceof Boolean) {
lenientDatumShift = ((Boolean) candidate).booleanValue();
}
}
this.lenientDatumShift = lenientDatumShift;
}
In ReferencingFactoryFinder, the 'getCoordinateOperationFactory' method is
basically implemented as below:
CoordinateOperationFactory getCoordinateOperationFactory(Hints hints) {
hints = addDefaultHints(hints);
return getServiceRegistry().getServiceProvider(
CoordinateOperationFactory.class, null, hints,
Hints.COORDINATE_OPERATION_FACTORY);
}
where 'addDefaultHints' is a private helper method as below:
private static Hints addDefaultHints(final Hints hints) {
final Hints completed = GeoTools.getDefaultHints();
if (hints != null) {
completed.add(hints);
}
return completed;
}
Martin
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Geotools-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/geotools-devel
