On 26/08/16 12:03, Andy Seaborne wrote:
On 26/08/16 00:28, Martynas Jusevičius wrote:
Hey,
EnhGraph JavaDoc contains:
"WARNING. The polymorphic aspects of EnhGraph are not supported and
are not expected to be supported in this way for the indefinite
future."
https://jena.apache.org/documentation/javadoc/jena/org/apache/jena/enhanced/EnhGraph.html
Is that supposed to mean Jena 3 does not support polymorphism, or
what?
No - the comment is much older than that.
Please clarify :)
I don't know what the javadoc comment means :-)
I do.
Once upon a time, when Jena2 was being invented, Jeremy invented Jena's
polymorphic node machinery, where a Resource in a Model may have
many different facets and you can use the .as() method to switch
between different facets of the same underlying node. All the
data about a facet is defined by the RDF Graph (= model for these
purposes) but of course might cache information. Changing facets
doesn't lose the information associated with a different facet.
We wondered if that same technique could be used to have
different kinds of Model as facets of an EnhGraph, so the same
entire graph could be presented in multiple different
ways.
However this turned out to be (a) a non-trivial extension of
the polymorphic resource machinery and (b) uncalled-for. But
we never got around to taking the hooks out. We just put a
comment in saying "don't try this". You're not missing
anything.
Chris
"Our future looks secure, but it's all out of our hands"
- Magenta, /Man and Machine/
