I thought the performance issue was solved by caching property accessors...
and that was done way back. I did not notice that the patch would change
that but I will have to look it over again.
The issue i am more concerned with before Jody took this thread in a
different direction was the compatibility one and change in behaviour.
Anyways, I look forward to the IRC breakout about this one. Hopefully we can
resolve this issue (if Jody lets us stay on task that is :P)
-Justin
On Tue, Sep 21, 2010 at 12:10 AM, Niels <[email protected]> wrote:
> On 21/09/10 12:05, Jody Garnett wrote:
>
> I understand the problem with using null to represent two cases; can you
> check the filter and xpath specifications to see how they handle this
> problem? Do they produce an error; or return an empty result? The answer may
> inform what we do here; perhaps they have thought of a good way to be clear?
>
> It seems to me that the filter specification doesn't mention the case of
> non-existent properties at all. It only mentions the case of a null value
>
>
> The *<PropertyIsNull> *element encodes an operator that checks to see if
> the value of its content is NULL. A NULL is equivalent to no value present.
> The value 0 is a valid value and is not considered NULL.
>
> 'The value of its content' implies to me that there is still a property,
> but this is open for interpretation of course.
>
> X-Path will return an 'empty list' when an element doesn't exist. There
> isn't really such a thing as null values in xpath as such.
>
>
> If you have a builder object for your mapping file could you make use of
> additional information to prevent an invalid mapping file being produced?
> Allow it to throw exceptions of the filters being passed in do not match the
> data they are to run on?
>
> Hmmm mappings are expressions that can contain functions, operators,
> etc... and properties can be evaluated with several property accessors. I do
> no see how the property names can be tested without recursively going
> through the expression tree and trying the several property accessors -
> basically evaluating it.
>
> --
> *Niels Charlier*
>
> Software Engineer
> CSIRO Earth Science and Resource Engineering
> Phone: +61 8 6436 8914
>
> Australian Resources Research Centre
> 26 Dick Perry Avenue, Kensington WA 6151
>
>
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--
Justin Deoliveira
OpenGeo - http://opengeo.org
Enterprise support for open source geospatial.
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