Re: [Geotools-gt2-users] new advanced tutorial on how to make a function

[Michael B. <mic...@gm...>]

Hello Jody,

Many thanks for this. It looks great.

I have a question that is peripheral to the tutorial, and that I know
we've gone over in the past: what is the valid use of a fallback value
with filter functions ?  The Symbology Encoding spec says:

"The value of the fallbackValue attribute is used as a default value,
if the SE implementation does not support the function. If the
implementation supports the function, then the result value is
determined by executing the function."

In that case, a function shouldn't even have a fallback value field should it ?

I remember struggling with this when helping to do the "env" function.
If you look at the code for EnvFunction you'll see that a "default"
value can be supplied as an optional extra arg to the evaluate method
(this was Andrea's suggestion for how to have a default while not
violating the spec). If the setFallbackValue is called an warning is
logged.

Sorry that this is banal feedback on a nice tutorial - but it's so
good to have a teaching page about filter functions at last so I think
it's worth checking that it's squeaky clean.

Michael


On 28 April 2011 01:08, Jody Garnett <jod...@gm...> wrote:
> Available now:
> - http://docs.geotools.org/latest/userguide/tutorial/advanced/function.html
> Review and feedback are of course welcome.
> --
> Jody Garnett
> --
> Jody Garnett
>
>
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