[PROJ] Management of datum grid files.

[Even Rouault]

Chris,

not going to answer to each specific point. I think you're proposing 
interesting ideas worth considering. The way we manage "static" proj-
datumgrid-XXXX packages is certainly not carved in stone. As RFC 4 already 
embraces quite a few different subjects and I need to limit my focus, I'd 
prefer we try to stick on them.
Discussing about that with Howard, he mentionned that packagers could probably 
have their own logic to fetch files of interest for them from the CDN. There 
are certainly further developments that can be built on top of that.

> I like python :-)  I'm not sure if it gives sufficient platform
> independence? 

Probably not the most convenient for Windows users that would have a naked 
installation, but I'm not sure we want to have a specific script for Windows. 
We can assume probably assume folks having a GIS stack to have Python not so 
far away.

> Do any of the proj binaries have a function to report the
> default value for PROJ_LIB that a python utility could use if it is not
> explicitly set?

No. The PROJ binary has no idea where PROJ_LIB can be pointed too. That's why 
it is needed to be defined. For some builds typically done by Linux 
distributions where the installaton path is known at build time, the default 
search path is hardcoded in the binary, but for Windows, the actual 
installation path is rarely known in advance.

Even

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