[PROJ] Management of datum grid files.

[Chris Crook]

Even

Cheers
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.

I wasn't thinking this is necessarily part of RFC 4 (other than potential relationship with CDN).
This more comes from trying to sort out the missing NZ height grids and where  to implement
and maintain 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.

I agree.   GDAL packages already include python scripts.  It certainly provides
and easy implementation for an initial version, and much better than nothing
even if there are some users who cannot use it.

> > 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.

I was thinking that once installed the proj utilities must know where they will
look for grid files, so I was just wondering what was the easiest way for a python
utility to determine this.   I'd thought maybe one of the utilities could report
status information including the default search path it was using in the installation.
Of  course programs using proj could reset PROJ_LIB so wouldn't necessarily be
using the same location :-(

Cheers
Chris

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