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Re: [Numbers] Inheritance and ValJO ? (Was: Where to define "quaternion"?)


I think this has already been worked out, but the main reason for no
inheritance is that is probably blocks future conversion to value types.
Composition instead of inheritance is usually the right solution.

Stephen


On Sun, 9 Dec 2018 at 10:21, Gilles <gilles@xxxxxxxxxxxxxxxxxxxxx> wrote:

> Hello.
>
> After the discussion quote below, the conclusion was to go with
> inheritance:
>    https://issues.apache.org/jira/browse/NUMBERS-80
>
> However, it would make "Quaternion" fail the "ValJO" definition[1]
> that mandates that all constructors be private.
>
> Would a protected constructor really be an issue?
> [In the case of "Quaternion", the subclass constructor would only
> perform additional validation (cf. below for details).]
>
>
> Thanks,
> Gilles
>
> [1] https://blog.joda.org/2014/03/valjos-value-java-objects.html
>
> On Mon, 03 Dec 2018 10:31:42 +0100, Gilles wrote:
> > Hi.
> >
> > On Mon, 3 Dec 2018 03:56:02 +0000, Matt Juntunen wrote:
> >> I was just thinking from a practical standpoint. My current
> >> QuaternionRotation class is still in my working branch for
> >> GEOMETRY-14
> >> and so isn't really accessible to anyone. If I can finish it up in
> >> its
> >> current state (hopefully very soon) and get it merged, then someone
> >> else will be able to work with it and blend the functionality with
> >> commons-numbers.
> >
> > Someone else?
> >
> >>
> >> Here are some notes on your questions from before:
> >>
> >>   * Should "QuaternionRotation" inherit from "Quaternion"?
> >>
> >> That would work conceptually. The quaternions in the
> >> QuaternionRotation class are standard quaternions that meet two
> >> other
> >> criteria: 1) they are unit length, and 2) their scalar component is
> >> greater than or equal to zero (in order to standardize the angles
> >> involved).
> >
> > It seems indeed the perfect case for inheritance.
> >
> >> The one sticking point here is that I'm not sure how this
> >> fits with the VALJO concept. If we can get this sorted, then this
> >> very
> >> well may be the best option.
> >
> > What do you see as a potential issue?
> >
> >>
> >>   * Should "Quaternion" be defined in [Geometry] (and removed from
> >> [Numbers])?
> >>
> >> Perhaps. I've certainly only used them to represent 3D rotations.
> >> Are
> >> there any other use cases from commons-numbers?
> >
> > Not within [Numbers], but that's the point of those very low-level
> > components/modules: they are common utilities used by higher-level
> > components/libraries/applications.
> >
> > Given that "QuaternionRotation" is a special case of "Quaternion",
> > it is logical to keep the latter at a lower-level, namely in
> > [Numebers], and make [Geometry] depend on it.
> >
> >>
> >>   * Are some utilities defined in "QuaternionRotation" general
> >>     such that they could be part of the [Numbers] "Quaternion" API.
> >>     An example might be the transformation between quaternion and
> >>     matrix (represented as a double[3][3])?
> >>
> >> The conversion to rotation matrix and slerp are the best candidates
> >> here. The other methods rely on core classes from commons-geometry,
> >> namely Vector3D.
> >
> > Is "slerp" applicable to a general "Quaternion", or does it assume
> > the additional requirements of "QuaternionRotation"?
> > [Same question applies to all utilities in order to decide where to
> > define them.]
> >
> >>
> >> One more note: I decided to make a separate package for 3D rotations
> >> in my working branch for GEOMETRY-14, so QuaternionRotation is now
> >> at
> >>
> >>
> https://github.com/darkma773r/commons-geometry/blob/transforms/commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/rotation/QuaternionRotation.java
> .
> >
> > Could you please update it so that it inherits from "Quaternion"?
> >
> > Thanks,
> > Gilles
> >
> >>
> >> -Matt
> >> ________________________________
> >> From: Gilles <gilles@xxxxxxxxxxxxxxxxxxxxx>
> >> Sent: Sunday, December 2, 2018 3:57 PM
> >> To: dev@xxxxxxxxxxxxxxxxxx
> >> Subject: Re: [Numbers][Geometry] Where to define "quaternion" (Was:
> >> Making Quaternion a VALJO)
> >>
> >> On Sun, 2 Dec 2018 19:20:03 +0000, Matt Juntunen wrote:
> >>> Unless anyone objects, I'm going to continue with what I'm working
> >>> on
> >>
> >> I certainly don't object on your working to improve the geometry
> >> code, but wherever that work overlaps with code being worked on
> >> elsewhere (in this case, the "Quaternion" class), then we'd
> >> rather have a discussion happening here first.
> >>
> >>> with QuaternionRotation and create a merge request. That way, we'll
> >>> at
> >>> least have a reference implementation and baseline functionality
> >>> for
> >>> commons-geometry that we can modify later based on what's decided
> >>> here.
> >>
> >> My questions below are a start; I'm waiting for answers.
> >> Code duplication is bad (TM).
> >>
> >> Regards,
> >> Gilles
> >>
> >>>
> >>> -Matt
> >>> ________________________________
> >>> From: Gilles <gilles@xxxxxxxxxxxxxxxxxxxxx>
> >>> Sent: Saturday, December 1, 2018 9:40 PM
> >>> To: dev@xxxxxxxxxxxxxxxxxx
> >>> Subject: Re: [Numbers][Geometry] Where to define "quaternion" (Was:
> >>> Making Quaternion a VALJO)
> >>>
> >>> On Sat, 01 Dec 2018 12:56:34 +0100, Gilles wrote:
> >>>> Hello.
> >>>>
> >>>> On Sat, 1 Dec 2018 06:05:31 +0000, Matt Juntunen wrote:
> >>>>> Hi guys,
> >>>>>
> >>>>> FYI, I've been working on a quaternion-related class named
> >>>>> QuaternionRotation for commons-geometry (see link below). It
> >>>>> includes
> >>>>> slerp as well as several other geometry-oriented methods, such as
> >>>>> conversion to/from axis-angle representations and creation from
> >>>>> basis
> >>>>> rotations. It's not quite ready for a merge yet since I still
> >>>>> need
> >>>>> to
> >>>>> finish the Euler angle conversions.
> >>>>>
> >>>>> I did not use the Quaternion class from commons-numbers since I
> >>>>> wanted to focus solely on using quaternions to represent 3D
> >>>>> rotations.
> >>>>> I felt like the commons-numbers class was too general for this.
> >>>>
> >>>> We need to explore further how to avoid duplication.
> >>>>
> >>>> Some questions:
> >>>>  * Should "QuaternionRotation" inherit from "Quaternion"?
> >>>>  * Should "Quaternion" be defined in [Geometry] (and removed from
> >>>>    [Numbers])?
> >>>>  * Are some utilities defined in "QuaternionRotation" general
> >>>>    such that they could be part of the [Numbers] "Quaternion" API.
> >>>>    An example might be the transformation between quaternion and
> >>>>    matrix (represented as a double[3][3])?
> >>>>
> >>>> The second consideration could apply to any computation that does
> >>>> not require types defined in [Geometry].  For example,
> >>>> interpolation
> >>>> is a purely quaternion-internal operation.
> >>>
> >>> s/second/third/
> >>>
> >>>>
> >>>> It looks to me that it should be possible to come up with a design
> >>>> that defines "rotation" in [Geometry] which uses a "quaternion"
> >>>> defined in [Numbers].
> >>>> Otherwise, one would wonder why "Complex" is also not in
> >>>> [Geometry]
> >>>> (for 2D rotations).
> >>>>
> >>>> Best regards,
> >>>> Gilles
> >>>>
> >>>>>
> >>>>> Regards,
> >>>>> Matt
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> https://github.com/darkma773r/commons-geometry/blob/transforms/commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/QuaternionRotation.java
> >>>>>
> >>>>>
> >>>>>
> >>>>> [https://avatars1.githubusercontent.com/u/3809623?s=400&v=4]<
> https://github.com/darkma773r/commons-geometry/blob/transforms/commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/QuaternionRotation.java
> >
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> darkma773r/commons-geometry<
> https://github.com/darkma773r/commons-geometry/blob/transforms/commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/QuaternionRotation.java
> >
> >>>>> Apache Commons Geometry. Contribute to
> >>>>> darkma773r/commons-geometry
> >>>>> development by creating an account on GitHub.
> >>>>> github.com
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> ________________________________
> >>>>> From: Gilles <gilles@xxxxxxxxxxxxxxxxxxxxx>
> >>>>> Sent: Friday, November 30, 2018 9:37 AM
> >>>>> To: dev@xxxxxxxxxxxxxxxxxx
> >>>>> Subject: Re: [numbers] Making Quaternion a VALJO
> >>>>>
> >>>>> On Fri, 30 Nov 2018 14:22:45 +0000, Steve Bosman wrote:
> >>>>>>> > and I have also emailed an ICLA.
> >>>>>>
> >>>>>>> Not received/acknowledged yet.
> >>>>>>
> >>>>>> I am now listed on the "Persons with signed CLAs but who are not
> >>>>>> (yet)
> >>>>>> committers." page.
> >>>>>
> >>>>> Welcome!
> >>>>>
> >>>>>>> > I think two convenience divide methods performing qr^{-1} and
> >>>>>>> r^{-1}q
> >>>>>>> > for q
> >>>>>>> > and r would be useful, but I couldn't think of nice names for
> >>>>>>> them.
> >>>>>>
> >>>>>>> What are the use-cases?
> >>>>>>> Why aren't "multiply" and "inverse" enough?
> >>>>>>
> >>>>>> I must admit I'm new to quaternions and stumbled into the
> >>>>>> project
> >>>>>> while
> >>>>>> trying to improve my understanding so I'm not going to claim
> >>>>>> great
> >>>>>> knowledge of how common these operations are. I was primarily
> >>>>>> thinking of
> >>>>>> Quaternion Interpolation - SLERP and SQUAD. It seems to me that
> >>>>>> you
> >>>>>> end up
> >>>>>> creating inverse instances and throwing them away a lot and I
> >>>>>> thought
> >>>>>> it
> >>>>>> would be good to reduce that overhead.
> >>>>>
> >>>>> Surely, the class "Quaternion" is minimal but, before adding to
> >>>>> the API, we be careful to have use-cases for low-level
> >>>>> operations.
> >>>>> Those mentioned above seems more high-level, tied to a specific
> >>>>> domain (see also "Commons Geometry", another new component not
> >>>>> yet
> >>>>> released) but I may be wrong...
> >>>>>
> >>>>> Regards,
> >>>>> Gilles
> >>>>>
> >>>>>>
> >>>>>> Steve
> >>>>>
> >>>>
>
>
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