[PROJ] Suggestion - add EPSG version to proj_info()

[Roger Bivand]

Even,

On Mon, 12 Apr 2021, Even Rouault wrote:

> Roger,
>
>
> Le 12/04/2021 à 11:10, Roger Bivand a écrit :
>>  I realise that simple SQL on proj.db can return the EPSG.VERSION key from
>>  the metadata table in proj.db, and that PROJ and EPSG versions are
>>  hard-wired in a single run-time. Could also the built-time EPSG version be
>>  made available?
>
> You can use proj_context_get_database_metadata(ctxt, "EPSG.VERSION")
>
>

Thanks, this is useful, and will be informative for others. Is there a 
table of PROJ version and EPSG version correspondence?

>>
>>  An alternative would be a mechanism to allow rgdal to use "its" PROJ
>>  search path, and GRASS (or other binary software) to use "its" search
>>  path, but while I implemented this for PROJ 6 in rgdal, I went back to
>>  PROJ_LIB because we need both the proj.db directory and the CDN download
>>  directory (on both sides, I expect).
>
> You can use proj_context_get_user_writable_directory() to retrieve it and 
> then add it along your regular "PROJ_LIB" directory with 
> proj_context_set_search_paths()
>

OK, thanks. For R packages (now rgdal, sf, terra and others distribute 
share/proj when built binary - Windows and MacOS), we'll need to work out 
in consort whether to combine our efforts, which may be tricky.

Thanks again!

Best wishes,

Roger

> Even
>
>
>

-- 
Roger Bivand
Emeritus Professor
Department of Economics, Norwegian School of Economics,
Postboks 3490 Ytre Sandviken, 5045 Bergen, Norway.
e-mail: Roger.Bivand at nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en