C++

  CRhinoCommand::result CCommandTest::RunCommand(const CRhinoCommandContext& context)
  {
    // Pick four curve objects
    CRhinoGetObject go;
    go.SetCommandPrompt( L"Select 4 curves" );
    go.SetGeometryFilter( CRhinoGetObject::curve_object);
    go.GetObjects( 4, 4 );
    if( go.CommandResult() != CRhinoCommand::success )
      return go.CommandResult();


    // Validate results
    int i, count = go.ObjectCount();
    if( count != 4 )
      return CRhinoCommand::failure;


    ON_NurbsCurve nc[4];
    // Get nurb form of each curve
    for( i = 0; i < count; i++)
    {
      const ON_Curve* crv = go.Object(i).Curve();
      if( !crv )
        return CRhinoCommand::failure;
      if( !crv->GetNurbForm(nc[i]) )
        return CRhinoCommand::failure;
    }


    // Create the surface
    ON_Brep* brep = RhinoCreateEdgeSrf( 4, nc );
    if( !brep )
    {
      RhinoApp().Print( L"Unable to create surface.\n" );
      return CRhinoCommand::failure;
    }


    // Ready new brep object
    CRhinoBrepObject* obj = new CRhinoBrepObject;
    obj->SetBrep( brep );


    // Add new objet to document
    if( !context.m_doc.AddObject( obj ) )
    {
      delete obj;
      RhinoApp().Print( L"Unable to create surface.\n" );
      return CRhinoCommand::failure;
    }


    context.m_doc.Redraw();
    return CRhinoCommand::success;
  }

VB.NET (Rhino 4)

  Public Overrides Function RunCommand(ByVal context As IRhinoCommandContext)_
    As IRhinoCommand.result
    ' Pick four curve objects
    Dim go As New MRhinoGetObject()
    go.SetCommandPrompt("Select 4 curves")
    go.SetGeometryFilter(IRhinoGetObject.GEOMETRY_TYPE_FILTER.curve_object)
    go.GetObjects(4, 4)
    If (go.CommandResult() <> IRhinoCommand.result.success) Then Return go.CommandResult()


    ' Validate results
    Dim count As Integer = go.ObjectCount()
    If (count <> 4) Then Return IRhinoCommand.result.failure


    Dim nc(3) As OnNurbsCurve
    For i As Integer = 0 To 3
      nc(i) = New OnNurbsCurve()
    Next


    ' Get nurb form of each curve
    For i As Integer = 0 To count - 1
      Dim crv As IOnCurve = go.Object(i).Curve()
      If (crv Is Nothing) Then Return IRhinoCommand.result.failure
      If (crv.GetNurbForm(nc(i)) = 0) Then Return IRhinoCommand.result.failure
    Next


    ' Create the surface
    Dim brep As OnBrep = RhUtil.RhinoCreateEdgeSrf(nc)
    If (brep Is Nothing) Then
      RhUtil.RhinoApp.Print("Unable to create surface." + vbCrLf)
      Return IRhinoCommand.result.failure
    End If


    ' Ready new brep object
    Dim obj As New MRhinoBrepObject()
    obj.SetBrep(brep)


    ' Add new object to document
    If (Not context.m_doc.AddObject(obj)) Then
      RhUtil.RhinoApp.Print("Unable to create surface." + vbCrLf)
      Return IRhinoCommand.result.failure
    End If


    context.m_doc.Redraw()
    Return IRhinoCommand.result.success
  End Function

C# (Rhino 4)

  public override IRhinoCommand.result RunCommand(IRhinoCommandContext context)
  {
    // Pick four curve objects
    MRhinoGetObject go = new MRhinoGetObject();
    go.SetCommandPrompt("Select 4 curves");
    go.SetGeometryFilter(IRhinoGetObject.GEOMETRY_TYPE_FILTER.curve_object);
    go.GetObjects(4, 4);
    if(go.CommandResult() != IRhinoCommand.result.success)
      return go.CommandResult();


    // Validate results
    int count = go.ObjectCount();
    if(count != 4)
      return IRhinoCommand.result.failure;
    OnNurbsCurve[] nc = new OnNurbsCurve[4];
    for( int i=0; i<4; i++ )
      nc[i] = new OnNurbsCurve();


    // Get nurb form of each curve
    for( int i=0; i<count; i++ )
    {
      IOnCurve crv = go.Object(i).Curve();
      if(crv == null)
        return IRhinoCommand.result.failure;
      if(crv.GetNurbForm(ref nc[i]) == 0)
        return IRhinoCommand.result.failure;
    }


    // Create the surface
    OnBrep brep = RhUtil.RhinoCreateEdgeSrf(nc);
    if(brep == null)
    {
      RhUtil.RhinoApp().Print("Unable to create surface.\n");
      return IRhinoCommand.result.failure;
    }


    // Add new object to document
    if(context.m_doc.AddBrepObject(brep) == null)
    {
      RhUtil.RhinoApp().Print("Unable to create surface.\n");
      return IRhinoCommand.result.failure;
    }
    context.m_doc.Redraw();
    return IRhinoCommand.result.success;
  }