[mapserver-dev] Scale Dependent Token Replacements: to mapscript ornot to mapscript

[thomas bonfort]

Worth,

I'm not sure I understand the "code mapfile specific information into
generic code which gets the specific information from the mapfile." part.
Could you give an example of that?

Supposing that you have a mapscript application that needs to modify a
layer's data based on scale:
Currently, you'd be doing something like:

setup map size and extent
if(scale<1000):
  layer.data="foo.shp"
else
   layer.data="bar.shp"
map.draw()

if mapscript had access to scaletokens, that code would become:

layer.setscaletoken("token",0,1000,"foo.shp")
layer.setscaletoken("token",1000,infinity,"bar.shp")
setup map size and extent
map.draw()

>From my point of view, the first method is clearer. I also can't really
come up with a use-case where a mapscript application would need to
*discover* what scaletokens where configured in a mapfile for a given
layer. Should such a use-case arise, then I agree that exposing scaletokens
would be necessary.
regards,

thomas

On Fri, Dec 14, 2012 at 3:16 PM, Worth Lutz <wal3 at mindspring.com> wrote:

>  As user of mapscript, I sometimes write generic code to use different
> mapfiles for either different clients or other reasons. The mapscript code
> is generic and the specifics are in the mapfile. In other words, I would
> not like to have to code mapfile specific information into generic code
> which gets the specific information from the mapfile.  ****
>
> ** **
>
> I have not thought much about this use case, but think that maybe a
> generic application written in mapscript might use this information in some
> way. Then again, just having the layer set up in the mapfile might be
> enough. Again I have not thought this through very well.****
>
> ** **
>
> That said, I have no immediate need where I might need to use this.****
>
> ** **
>
> Thanks to all the MapServer Developers,****
>
> ** **
>
> Worth Lutz****
>
> ** **
>  ------------------------------
>
> *From:* mapserver-dev-bounces at lists.osgeo.org [mailto:
> mapserver-dev-bounces at lists.osgeo.org] *On Behalf Of *thomas bonfort
> *Sent:* Friday, December 14, 2012 3:42 AM
> *To:* MapServer Dev Mailing List
> *Subject:* [mapserver-dev] Scale Dependent Token Replacements: to
> mapscript ornot to mapscript****
>
> ** **
>
> Devs,****
>
> ** **
>
> There's a point that I overlooked when submitting RFC86, which concerns
> exposing the scale dependent token mechanism to mapscript.****
>
> ** **
>
> I'd argue that the whole point of the RFC is to simplify mapfile
> management thus avoiding the use of mapscript in a number of cases, and
> that there is no real usecase in exposing this API to mapscript (as a
> mapscript script can do these replacements directly on the layer's
> data/filter).****
>
> If there is no objection, I will amend the mapscript part of the RFC to
> state: "Given the more straightforward methods to obtain the same results
> as this RFC in mapscript, access to a layer's SCALETOKENs will  not be
> exposed to mapscript for the time being".****
>
> ** **
>
> So, are there any objections? :)****
>
> ** **
>
> cheers,****
>
> thomas****
>  ------------------------------
>
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