On Sat, Jan 29, 2011 at 7:17 PM, Justin Deoliveira <[email protected]> wrote:
> I don't think it requires a proposal since as you mention the impact is
> pretty small. I would just ask for a complete javadoc on the
> VolatileFunction interface explaining its role.
Works for me. Let me try it out:
-------------------------------------------------------------------------
package org.opengis.filter.expression;
/**
* <p>
* Marker interface indicating that that the function return value can
change during a single data
* access operation even if the argument values provided to it remain constant
* </p>
* <p>
* Very few functions are truly volatile, one example being random(),
whose value is going to change
* over each invocation, even during the same feature collection filtering
* </p>
* <p>
* Functions whose value changes over time but not within the same
feature collection filtering are
* considered to be <em>stable</em> and as such their result can be
considered a constant during the
* single data access operation
* </p>
* <p>
* GeoTools will try to optimize out the stable functions and replace
them with a constant that can
* be easily encoded in whatever native filtering mechanism the datastores have
* </p>
* <p>
* Given the vast majority of function are <em>stable</em> by the
above definition only the fews
* that aren't suitable for constant replacement during a single run
against a feature collection
* should be marked as <em>volatile</em>
*
* @author Andrea Aime - GeoSolutions
*/
public interface VolatileFunction extends Function {
}
-------------------------------------------------------------------------
Feedback welcomed
Cheers
Andrea
--
Ing. Andrea Aime
Technical Lead
GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584962313
fax: +39 0584962313
http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://www.linkedin.com/in/andreaaime
http://twitter.com/geowolf
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