[vtk-developers] Implicit copy constructors in VTK

[Marcus D. Hanwell]

I agree with Rob, and can take care of putting a patch together for
the classes you call out. The rules outlined only make sense for
vtkObject derived classes, we should provide clear guidelines for
those that are not part of that hierarchy too.

On Wed, Jul 24, 2013 at 11:06 AM, Robert Maynard
<robert.maynard at kitware.com> wrote:
> The VTK coding standards should be amended to state that those rules
> are only valid for classes that derive from vtkObject.
>
> Classes like vtkBond, vtkTuple, vtkBoundingBox all which don't inherit
> from vtkObject should follow the rule of three and implement the copy
> and assignment constructor if they implement a destructor.
>
> On Wed, Jul 24, 2013 at 10:50 AM, Sean McBride <sean at rogue-research.com> wrote:
>> Hi all,
>>
>> So I'm looking at the clang warnings on Rogue7, but need C++ help before I can proceed further.  We have two similar warnings, repeated for several classes:
>>
>> VTK/Common/DataModel/vtkBond.h:30:3: warning: definition of implicit copy constructor for 'vtkBond' is deprecated because it has a user-declared destructor [-Wdeprecated]
>>   ~vtkBond();
>>   ^
>>
>> VTK/Common/Math/vtkQuaternion.h:201:8: warning: definition of implicit copy constructor for 'vtkQuaternion<float>' is deprecated because it has a user-declared copy assignment operator [-Wdeprecated]
>>   void operator=(const vtkQuaternion<T>& q);
>>        ^
>>
>> From what I can tell, in C++11, the implicit generation of copy constructors is now deprecated if 1) you provide a user-declared destructor or 2) you provide a user-declared copy assignment operator.
>> <http://stackoverflow.com/a/11255258>
>>
>> So it would seem a solution is to provide an explicit copy constructor, but VTK's coding standards gives me pause: "Classes should have protected constructors and destructors, and privately declared but unimplemented copy constructor and assignment operator. Rationale: VTK’s reference counting implementation depends on carefully controlling each object’s reference count".
>>
>> So now I'm not sure how to proceed...
>>
>> Thanks,
>>
>> --
>> ____________________________________________________________
>> Sean McBride, B. Eng                 sean at rogue-research.com
>> Rogue Research                        www.rogue-research.com
>> Mac Software Developer              Montréal, Québec, Canada
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