[vtk-developers] Implicit copy constructors in VTK

[Jean-Christophe Fillion-Robin]

@Robert, @Bill:  My initial motivation was to make it easier for novice to
review/follow/understand the code. Not having user feedback to support
this, I will plan on doing a survey of our Slicer users/developers.


On Wed, Jul 24, 2013 at 12:51 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> I agree with Robert. I'd rather see the explicit lions rather than a
> macro. Makes code easier to follow for novices.
>
>
>
> On Wed, Jul 24, 2013 at 12:33 PM, Robert Maynard <
> robert.maynard at kitware.com> wrote:
>
>> Personally I don't see enough complaints about people forgetting to
>> follow the rule of three to add another macro helper to VTK.
>> We have a smoke test that does verify that all classes that derive
>> from vtkObject have private copy constructor and copy assignment
>> operator.
>>
>>
>> On Wed, Jul 24, 2013 at 11:55 AM, Jean-Christophe Fillion-Robin
>> <jchris.fillionr at kitware.com> wrote:
>> > Would it make sense to provide a VTK_DISABLE_COPY() macro ?  (Similar to
>> > what is done within Qt with Q_DISABLE_COPY [1])
>> >
>> > [1] http://qt-project.org/doc/qt-5.0/qtcore/qobject.html#Q_DISABLE_COPY
>> >
>> >
>> > On Wed, Jul 24, 2013 at 11:48 AM, Marcus D. Hanwell
>> > <marcus.hanwell at kitware.com> wrote:
>> >>
>> >> 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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>> >
>> > --
>> > +1 919 869 8849
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>
>
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> Unpaid intern in BillsBasement at noware dot com
>



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