[PROJ] Disable .local in 7.0.0RC default search paths

[Roger Bivand]

On Sun, 23 Feb 2020, Even Rouault wrote:

>> Thanks, I guess the links will work once it is live
>
> Yes
>
>> - proj-ini isn't a function and grep doesn't find it in the 7.0.0 source
>
> There:
> https://github.com/OSGeo/PROJ/blob/master/docs/source/resource_files.rst#projini

OK, probably not the R package case.

>
>> , environment
>> variables are potentially fragile (multiple loaded packages in an R
>> session may try to set them), so the proj_context_set_enable_network()
>> function may work.
>>
>> However, in a long-running session is also not great. I've been creating
>> and closing ctx handles before and after each use of PRØJ, I'll need to
>> preserve the context for the duration of the session, I suppose, will I
>> not?
>
> Do you mean: if you want to enable network functionality ? You're not obliged to
> change the way you manage PROJ contexts in that regard. But maintaining PROJ context
> alive as long as possible is strongly encouraged for more performance if instanciating
> many coordinate operations, independently of network functionality.
>

I'll look at this carefully - it has always been the case for GDAL that we 
use object handles, so code to preserve a pointer to a GDAL object or 
GEOS context exists.

>> I use this in the alternative workflow - list candidates and choose the
>> best available, and go to proj_trans_* with a prepared pipeline. For 6,
>> this was just giving the name of the grid - will 7 encode the part of the
>> grid used, or will this also use the area of interest?
>
> A grid should be considered as a single object. PROJ 7 with network 
> functionality enabled can download only the part of the grids needed, 
> but this is an implementation & optimization detail, not aimed to be 
> user visible.

This is a very useful clarification, thanks. Looking at 
networkfilemanager.cpp, I can see plenty of functions giving insight when 
I need it. For now, I can add an rgdal load-time comment from 
pj_context_is_network_enabled() to confirm that the network functionality 
is disabled.

Roger

>
> Even
>
>

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: Roger.Bivand at nhh.no
https://orcid.org/0000-0003-2392-6140
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