On 11/8/06, Mikael Högqvist <[EMAIL PROTECTED]> wrote:
> Hello again,
> I found another small bug. When giving an empty prefix name in a
> SPARQL query I get: TypeError: unsupported operand type(s) for +:
> 'NoneType' and 'unicode'
>
> This happens in SPARQLEvaluate.py in the convertTerm method. I tried
> making a small patch for it and a test case (see attachment).
>
> I'm interested in getting the SPARQL engine to support a larger subset
> of the SPARQL spec. Especially nested optionals. Is anyone working on
> this currently?

I have been (in part) but I've been stumped by the fact that the
current evaluation method ( sparql.queryObject ) is limited in the
kinds of patterns it can handle - as pointed out earlier.  I've taken
the time instead to try to familiarize myself with the recent paper on
SPARQL semantics [1] in order to determine how to 'fully' implement
the composition approach (as described there) to SPARQL evaluation.

All the pieces are there to support the full specification, the
challenge is to rewrite or refactor the existing expantion tree
mechanism to accomodate a moving target (the spec) without any formal
understanding of the consequences.

If you have any ideas in this regard, please share.

[1] http://www.dcc.uchile.cl/~cgutierr/papers/sparql.pdf

>
> Cheers,
> Mikael
>
>
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