Geometry Boost List: [ggl] [order] 2: read_wkt to read

Subject: [ggl] [order] 2: read_wkt to read
From: Barend Gehrels (barend)
Date: 2011-02-27 06:49:47

Hi,

Yesterday I mailed part 1 of the order of parameters (combine). This is 
about read_wkt.

It's signature: void read_wkt(string, Geometry);

should probably change to read_wkt(Geometry, string) to conform to the 
order GeometryIn, GeometryOut, others.

At the same time, read_wkt is currently an extension. It is extensively 
used in nearly every testcase, many samples, etc. If we go to the 
release-branche, we either should skip all extensions or move WKT to 
something else.

To allow for all these changes at the same time, I propose the following.

1) We make a new folder "domains" which is subdivided as the 
"extensions" are. So we now get a:
domains/gis/io/wkt for the WKT-parser.

2) We move wkt to there

3) At the higher level (in io, or in domains, or in algorithms) we make 
one new algorithm called "read". This one has a required template 
parameter denoting the format. And it reverses the arguments. So we get, 
for example:

polygon_2d triangle;
boost::geometry::read<format_wkt>(triangle, "POLYGON((1 1,1 2,2 1,1 1))");

and we can get the same for format_wkb and possibly other formats we 
will support for reading. There even might be a format_autodetect which 
figures out the format from the string. In OGC this algorithm is called 
geomfromtext, returning a geometry. I had this earlier but it was 
discarded because there are so many text formats, but now we might 
consider using that name again.

Changing all read_wkt to read<format_wkt> will be a bigger change 
especially for me, because of all tests (reversing the arguments), but I 
think it is manageable, and better like this. The read_wkt function 
itself can stay in extensions for backwards compatiblity, with a 
compiler warning that it is deprecated.

There is one tweak, because there is also:
read_wkt(std::string const& wkt, OutputIterator out)
only working for linestring and ring. This case is probably not used and 
might be deprecated either (so no new function read<format_wkt> for it).

Objections to this all?

Regards, Barend

-- 
Barend Gehrels
http://about.me/barendgehrels