[postgis-devel] POINT EMPTY in WKB

[Mateusz Loskot]

On 06/12/10 18:01, Paul Ramsey wrote:
> A final possibility would be to hack POINT EMPTY into WKB, as
> something like POINT(nan nan nan) or POINT(inf inf inf) or POINT(-0 -0
> -0). There would be a danger there in platforms that have different
> interpretations of what nan, inf or -0 are in binary.
> 
> Discussion?

If C/C++ was Fortran, it would be possible to use the well-known
NaN and INF  bit patterns to mean uninitialized values:

http://bit.ly/eINabI

In C/C++, this kind of solution is potentially non-portable.

Very similar idea was discussed on Boost ml about using
those bit patterns to mean uninitialized float-point values
for use with Boost.Serialization library:

http://lists.boost.org/Archives/boost/2005/11/96941.php

Although, this thread may turn into a useful resource.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org
Member of ACCU, http://accu.org