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9588 :: C++ binding - error: use of deleted function

• mantielero (orginal) [2022-11-07T22:17:33+01:00] view original

  I keep on playing with OpenCascade library. I am trying to visualize something on the screen. For that purpose, I am trying to mimic a simplified version of this example.

  My Nim code (very ugly, I know) goes as follows:

  import occt
  
  #-----
  # 1. Type definition
  #------
  type
    OcctAisHello* = object of AIS_ViewController
      myContext*:Handle[AISInteractiveContext]
      myView*:Handle[V3d_View]
  
  
  # Return context.
  proc context(this:OcctAisHello):Handle[AIS_InteractiveContext] =
    return this.myContext
  
  
  # Return view.
  proc view(this:OcctAisHello):Handle[V3d_View] =
    return this.myView
  
  
  # --------------------------------------
  # 2. This is the constructor
  # --------------------------------------
  proc newOcctAisHello*():OcctAisHello =
    # graphic driver setup
    var aDisplay:Handle[Aspect_DisplayConnection] = newHandle( cnew newAspectDisplayConnection() )
    var aDriverOpenGl:Handle[OpenGlGraphicDriver] = newHandle( cnew newOpenGlGraphicDriver(aDisplay) )
    var aDriver:Handle[Graphic3d_GraphicDriver]   = newHandle( cast[ptr Graphic3d_GraphicDriver](aDriverOpenGl.get) )
    #var aDriver:Graphic3d_GraphicDriver   = aDriverOpenGl.downcast
    
    
    # viewer setup
    var aViewer:Handle[V3d_Viewer] = newHandle( cnew newV3dViewer( aDriver ) )
    `*`(aViewer).setDefaultLights()
    `*`(aViewer).setLightOn()
    
    # view setup
    var myView = newHandle( cnew newV3dView(aViewer) )
    var aWindow:Handle[Xw_Window] = newHandle( cnew newXwWindow(aDisplay, "OCCT Viewer", 100, 100, 512, 512) )
    var aWinAspect:Handle[AspectWindow] = newHandle( cast[ptr AspectWindow](aWindow.get) )
    # Atom aDelWinAtom = aDisplay->GetAtom (Aspect_XA_DELETE_WINDOW);
    `*`(myView).setWindow(aWinAspect)
    `*`(myView).setBackgroundColor( newQuantityColor(quantity_NOC_GRAY50) )
    `*`(myView).triedronDisplay( aspectTOTP_LEFT_LOWER, newQuantityColor(quantity_NOC_WHITE), 0.1 )
    `*`(myView).changeRenderingParams().renderResolutionScale = 2.0
    
    # interactive context and demo scene
    var myContext = newHandle( cnew newAISInteractiveContext(aViewer) )
    result.myContext = myContext
    result.myView    = myView
    #var aSolid:TopoDS_Solid = box(100.0,100.0,100.0).solid()
    var mybox = box(1.0, 2.0, 3.0)
    mybox.build()
    var solid:TopoDS_Solid =  mybox.solid()
    if solid.isNull:
      raise newException(ValueError, "Can't export null shape to STEP")
    
    var aShape:TopoDS_Shape = solid
    var aShapeAis:Handle[AIS_Shape] = newHandle( cnew newAISShape(aShape) )
    var aShapePrs:Handle[AIS_InteractiveObject] = newHandle( cast[ptr AIS_InteractiveObject](aShapeAis.get) )
    `*`(myContext).display(aShapeAis, AIS_Shaded.cint, 0, false)
    `*`(myView).fitAll(0.01, false)
    
    `*`(aWindow).map()
    `*`(myView).reDraw()
  
  # --------------------------------------
  # 3. Here it is define the main function
  # --------------------------------------
  proc main =
    var aViewer:OcctAisHello = newOcctAisHello()
    # X11 event loop
    var aWindow:Handle[Xw_Window] = newHandle( cast[ptr Xw_Window]( `*`(`*`(aViewer).view()).window) )
    var aDispConn:Handle[Aspect_DisplayConnection] = `*`(`*`(`*`(aViewer.view()).viewer()).driver()).getDisplayConnection()
    
    var anXDisplay:Display = `*`(aDispConn).getDisplay()[]
    
    #while true:
    #  discard
  
  main()
  Run

  When I compile it, I get the error:

  
  CC: stdlib_digitsutils.nim
  CC: stdlib_dollars.nim
  CC: stdlib_system.nim
  CC: viewer04.nim
  /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp: In function 'tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg newOcctAisHello__viewer4852_24()':
  /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp:481:16: error: use of deleted function 'tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg::tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg(const tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg&)'
    481 |         return result;
        |                ^~~~~~
  /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp:89:8: note: 'tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg::tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg(const tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg&)' is implicitly deleted because the default definition would be ill-formed:
     89 | struct tyObject_OcctAisHello__4FfLiMkIhaAMoZFVAV19cSg : public AIS_ViewController {
        |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp:89:8: error: use of deleted function 'AIS_ViewController::AIS_ViewController(const AIS_ViewController&)'
  In file included from /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp:8:
  /usr/include/opencascade/AIS_ViewController.hxx:54:7: note: 'AIS_ViewController::AIS_ViewController(const AIS_ViewController&)' is implicitly deleted because the default definition would be ill-formed:
     54 | class AIS_ViewController
        |       ^~~~~~~~~~~~~~~~~~
  /usr/include/opencascade/AIS_ViewController.hxx:54:7: error: use of deleted function 'Aspect_VKeySet::Aspect_VKeySet(const Aspect_VKeySet&)'
  In file included from /usr/include/opencascade/AIS_ViewController.hxx:17:
  /usr/include/opencascade/Aspect_VKeySet.hxx:25:7: note: 'Aspect_VKeySet::Aspect_VKeySet(const Aspect_VKeySet&)' is implicitly deleted because the default definition would be ill-formed:
     25 | class Aspect_VKeySet : public Standard_Transient
        |       ^~~~~~~~~~~~~~
  compilation terminated due to -fmax-errors=3.
  Error: execution of an external compiler program 'g++ -c -std=gnu++14 -funsigned-char  -w -fmax-errors=3 -fpermissive -I/usr/include/opencascade/   -I/home/jose/.choosenim/toolchains/nim-1.6.6/lib -I/home/jose/src/nimlang/occt.nim/examples -o /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp.o /home/jose/src/nimlang/occt.nim/examples/cache/@mviewer04.nim.cpp' failed with exit code: 1
  Run

  This is a bit too cryptic for me.

  The generated C++ code is here.

  Any idea about what am I doing wrong?

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• rb3 (orginal) [2022-11-07T23:49:07+01:00] view original

  That looks like it's saying a copy constructor is marked deleted from a class which you inherit from (e.g. in AIS_ViewController), and that something in your code is implicitly trying to invoke that copy constructor.

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• demotomohiro (orginal) [2022-11-08T00:08:10+01:00] view original

  I think you need to learn more about C++ language as long as you write C++ library wrapper yourself. If you use only Nim language or use a Nim library that wraps C++ library nicely and is written by C++ expert, you might not need to learn C++. But you are wrapping C++ library and got compile errors from backend C++ compiler.

  Also, using a library correctly usually requires reading the manual of it. C++ library's manual are written for C++ programmer. So reading C++ library manual requires C++ knowledge.

  C++ is old and popular. There are many books or web sites for learning C++. Learning C++ might takes some times but you should be able to fix errors faster yourself after learning C++. That would be better than using C++ libraries without knowing C++ and ask questions everytime you got C++ errors and wait for someone provides the answer.

  I guess AIS_ViewController deleted its copy constructor in order to forbid copying it. But return result; requires copying result. I think you need to read a Open CASCADE manual/tutorial/user guides/etc to use that type correctly. https://dev.opencascade.org/doc/overview/html/index.html

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• mantielero (orginal) [2022-11-08T18:38:33+01:00] view original

  Thanks for the advices. That was the issue.

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