[geos-devel] Refactoring CoordinateSequence

[Vicky Vergara]

In GEOS there are 2 classes about Coordinate Sequence
https://cvvergara.github.io/GEOS/classgeos_1_1geom_1_1CoordinateSequence.html
https://cvvergara.github.io/GEOS/classgeos_1_1geom_1_1CoordinateArraySequence.html

CoordinateArraySequence is "an Array view" for CoordinateSequence
I find these 2 classes confusing, normally you use CoordinateSequence, some
operations are accesible only through CoordinateArraySequence
Very strange desing for those 2 classes (I would first "merge" both classes
into one, SetAt is on CoordinateArraySequence)

I dont object on re-design (hey I like to do this kind of stuff), but a
careful analysis (experimentation of ideas, like the one above) needs to be
made, because the CoordinateSequence is used in may parts of GEOS.

Regards
VIcky

I was never "married" to JTS, I think GEOS must get "divorced" of JTS, and
a re-design is part of the divorce papers :)





On Thu, Aug 30, 2018 at 11:00 AM, Regina Obe <lr at pcorp.us> wrote:

> Great.  I'm fine with it then – adding to C-APi is fine, removing not so
> fine.
>
>
>
> *From:* geos-devel [mailto:geos-devel-bounces at lists.osgeo.org] *On Behalf
> Of *Daniel Baston
> *Sent:* Thursday, August 30, 2018 11:20 AM
> *To:* GEOS Development List <geos-devel at lists.osgeo.org>
> *Subject:* Re: [geos-devel] Refactoring CoordinateSequence
>
>
>
> Hi Regina,
>
>
>
> This work would be not cause any changes to the C API, though we would
> ultimately want to add some functions to the C API to create packed
> coordinate sequences.
>
>
>
> Dan
>
>
>
> On Thu, Aug 30, 2018 at 9:53 AM Regina Obe <lr at pcorp.us> wrote:
>
> I have no objection.  I know Vicky was complaining about the large number
> of functions that should be private that are exposed. She was planning to
> deprecate them in 3.8 and remove/make private in a later release.
>
>
>
> I'm not sure if this is related to that if she's even looked at that
> class.  Are these linked into CAPI at all?  If so we should probably stub
> them with an error, if not, I don't care if they are removed as we never
> said the C++ -API is stable yet.  My hope is once we clean things up a bit,
> we can guarantee some level of stability for the C++ API as well.
>
>
>
>
>
> Thanks,
>
> Regina
>
>
>
> *From:* geos-devel [mailto:geos-devel-bounces at lists.osgeo.org] *On Behalf
> Of *Daniel Baston
> *Sent:* Thursday, August 30, 2018 9:10 AM
> *To:* GEOS Development List <geos-devel at lists.osgeo.org>
> *Subject:* [geos-devel] Refactoring CoordinateSequence
>
>
>
> I've been exploring porting the PackedCoordinateSequence from JTS to GEOS
> because it seems like a useful way to improve the interoperability of GEOS
> with other code (LWGEOM, for example) without requiring copying of
> everything into GEOS data structures. It turns out that extending
> CoordinateSequence is pretty onerous in GEOS; the CoordinateSequence class
> contains many abstract methods that are not in the corresponding
> CoordinateSequence JTS interface. These methods add requirements of
> mutability (CoordinateSequence::setAt) and extensibility/contractability
> (CoordianteSequence::add, CoordianteSequence::deleteAt) and require the
> author of a derived class to implement functionality that could be seen as
> unrelated to storing a sequence of coordinates (removeRepeatedPoints,
> apply_ro, etc.). Does anyone know why so many methods are added to GEOS
> CoordinateSequence that have no JTS equivalent, and are there any
> objections to factoring some of the functionality out of the
> CoordianteSequence class so that it's easier to write other
> CoordinateSequence implementations?
>
>
>
> Dan
>
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>
>
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>



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Vicky Vergara
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