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https://issues.apache.org/jira/browse/JENA-270?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13400979#comment-13400979
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Rob Vesse commented on JENA-270:
--------------------------------
Where exactly does eval(List<ValueNode>) method come from, this does not
appears to be in the main Expr interface rather appears to be an artifact of
ExprFunctionN?
I can't figure out how I would implement it anyway since there doesn't appear
to be a way to call that on an arbitrary expression so even if I can use the
first value to create an expression I can't evaluate it because I'd have to
convert back into a Binding and a FunctionEnv in order to call eval(Binding,
FunctionEnv) on it. Is that even possible?
> Support dynamic function invocation in ARQ
> ------------------------------------------
>
> Key: JENA-270
> URL: https://issues.apache.org/jira/browse/JENA-270
> Project: Apache Jena
> Issue Type: New Feature
> Components: ARQ
> Affects Versions: ARQ 2.9.2
> Reporter: Rob Vesse
> Assignee: Rob Vesse
> Labels: call, dynamic, functions, sparql
> Fix For: ARQ 2.9.2
>
>
> Per my suggestion to the SPARQL Working Group I am proposing a new built in
> CALL() which can be used in SPARQL queries for dynamic function invocation.
> CALL with no argument returns null
> CALL with some arguments evaluates the first argument, sees if the result is
> a URI (if not errors) and if so tries to generate a function from it and
> invoke it with the arguments to that invocation being the remaining arguments
> to CALL
> I have implemented a prototype implementation of this in the ARQ language
> which I have committed to Trunk, others with more knowledge of expression and
> function evaluation in ARQ may have suggestions on how to improve the
> implementation
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