[x3d-public] SFRotation constructor axis argument by reference or value ?

[Don Brutzman]

[Dick and I are on a teleconference]

The way that you have written this, it looks to us like each object is independent.

Thus if you create a 'rot' SFRotation object, its values are passed by value only change if they are directly modified.

This seems to be a straightforward case of object encapsulation.  For those interested in learning more, general information:

* Encapsulation (computer programming)
   https://en.wikipedia.org/wiki/Encapsulation_(computer_programming)


On 3/3/2020 7:06 AM, Andreas Plesch wrote:
> In the ecmascript SAI, SFRotation has a constructor which has the
> rotation axis as a SFVec3f argument:
> 
> new SFRotation ( SFVec3f axis, numeric  angle )
> 
> https://www.web3d.org/documents/specifications/19777-1/V3.3/Part1/functions.html#SFRotation
> (Table 7.18, -url in the first sentence is off-)
> 
> The question is when I make a new SFRotation and later change the
> SFVec3f which was used for the axis, does the previously constructed
> SFRotation also change ?
> 
> axis = new SFVec3f ( 0, 0, 1 );
> rot = new SFRotation( axis, 3.14 );
> axis.y = 1.0
> axis.z = 0.0
> // rot.y is ?
> // constructed by value: rot.y = 0.0
> // constructed by reference: rot.y = 1.0
> 
> I did not check the abstract SAI spec. for guidance so it is very
> possible I missed something.
> 
> This is just an example. There are of course other constructors which
> use objects as parameters. It is also probably rare that a script
> would want to do this.
> 
> It may depend on the scripting language. In ecmascript objects are
> passed by reference, you have to explicitly make a copy if you need
> it. This is for performance. So I would guess for ecmascript it should
> be rot.y = 1.0 .
> 
> -Andreas


all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman