Python: duplicate RhinoCommon structure

Replies to This Discussion

Permalink Reply by Florian Frank on November 12, 2013 at 1:26pm

Hi Emilio,

this is not a stupid question. You're talking about a so called deep-copy of an object. You can call it a copy-constructor but Point3d and Plane are an Exception for this type of constructors.

All GeometryBase based classes:

  Rhino.Geometry.GeometryBase
      Rhino.Geometry.AnnotationBase
      Rhino.Geometry.Brep
      Rhino.Geometry.BrepLoop
      Rhino.Geometry.Curve
        Rhino.Geometry.ArcCurve
        Rhino.Geometry.CurveProxy
        Rhino.Geometry.LineCurve
        Rhino.Geometry.NurbsCurve
        Rhino.Geometry.PolyCurve
        Rhino.Geometry.PolylineCurve
      Rhino.Geometry.DetailView
      Rhino.Geometry.Hatch
      Rhino.Geometry.InstanceDefinitionGeometry
      Rhino.Geometry.InstanceReferenceGeometry
      Rhino.Geometry.Light
      Rhino.Geometry.Mesh
      Rhino.Geometry.MorphControl
      Rhino.Geometry.Point
      Rhino.Geometry.Point3dGrid
      Rhino.Geometry.PointCloud
      Rhino.Geometry.Surface
      Rhino.Geometry.TextDot

have inherited the method  Duplicate(), which makes a full (deep) copy of that object and returns a GeometryBase object. For all other types like Line, Arc, Circle, there are no comparing methods.

But you can cast a line/arc/circle/ellipse to a NurbsCurve duplicate that one. Later on you can convert the obtained GeometryBase object back to your desired type with these Methods:

TryGetArc(Arc, Double), TryGetCircle(Circle), TryGetEllipse(Ellipse).

I hope this answers your question.

Cordiali saluti,

FF

Permalink Reply by Emilio Morello on November 12, 2013 at 2:57pm

Hi Florian,

many thanks for your clear explanation !

Indeed I copied the arc by an instruction like:

    newarc = Rhino.Geometry.ArcCurve( oldarc ).Arc

I'm glad to see that it's also what you suggest.  :)   ( I wasn't sure about it )

But I'm not glad to learn that there is no better way ...  ;)

... Having to create a class instance to copy a structure instance feels somewhat strange ...

OK, problem solved.

Thanks again !

Saluti

emilio

Permalink Reply by David Rutten on November 12, 2013 at 3:11pm

Emilio,

if oldarc is of type Rhino.Geometry.Arc, you can just assign it directly and a copy will be made:

Arc newArc = oldArc;

oldArc.Radius = 5;

at this point newArc will still have the old radius.

--

David Rutten

david@mcneel.com

Tirol, Austria

Permalink Reply by Emilio Morello on November 12, 2013 at 3:34pm

Hi David,

please correct me if I'm wrong.

I think that copy by assignment for structures works fine in VB and C#, but I just learned (the hard way ...) that Python works differently.

It seems that structure instances are copied by reference, just like class instances ...

Thanks for replying !

emilio

Permalink Reply by Anders Holden Deleuran on November 12, 2013 at 2:46pm

I suppose that a generic Python specific approach would be to use the copy module. See attached file. Also, really great post Florian.

Attachments:

• GHPython_CopyObject.gh, 4 KB

Permalink Reply by Florian Frank on November 12, 2013 at 3:12pm

That's awesome...these kind of things are the reason people should do python instead of vb/c# ;-)

Thanks Anders

Permalink Reply by Anders Holden Deleuran on November 12, 2013 at 3:17pm

Careful now, no worries ;)

Permalink Reply by Emilio Morello on November 12, 2013 at 3:27pm

Hi Anders,

nice idea ! Works fine.  :)

Thanks a lot !