Hi Eric.

On 26/05/2015 03:00 μμ, Eric MSP Veith wrote:
Hello Menelaos,

On Tuesday 26 May 2015 14:47:20, Menelaos Karavelas 
<menelaos.karavelas@gmail.com> wrote:

Yes, this IS the correct way. You need to specialize various
metafunctions in bg::traits namespace so that things work.
Please keep up posted about this.

ok, good to know. I've followed this path and provided template 
specializations for clear, resize, and push_back. The test program you 
supplied now compiles, but gives a rather surprising result:

geometry: LINESTRING(1 1,2 2,3 3,4 4,9 9)
points: (1, 1) (2, 2) (3, 3) (4, 4) (9, 9)
segments: ((2.0872e-317, 6.95257e-310), (6.91222e-310, 6.91222e-310)) 
((2.0872e-317, 6.95257e-310), (6.91222e-310, 6.91222e-310)) ((2.0872e-317, 
6.95257e-310), (6.91222e-310, 6.91222e-310)) ((2.0872e-317, 6.95257e-310), 
(6.91222e-310, 6.91222e-310))

The values of the last line change with each run, but never much, i.e., the 
value left to the dot remains the same.

My understanding is that something is left uninitialized, hence the strange values.

Do I need to provide a separate segment iterator...?

You should not need to. The implementation of the segment iterator is rather generic, but quite tricky, as it is not the typical kind of iterator (for example, dereferrencing returns a value rather than a reference).

What is your linestring's value type and reference type? In the implementation of the segment iterator it is assumed that, when dereferrencing an iterator on the points of the linestring, a reference (or const reference) is returned. If your linestring iterator returns point values then this could indeed be a problem.

- m.

Thanks
Eric


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