[vtk-developers] vtkNew<>

[David Gobbi]

I guess that I should really give an example:

#include "vtkObject.h"
#include "vtkNew.h"

class vtkTransform;

class vtkMyClass: public vtkObject
{
...

protected:

  vtkNew<vtkTransform> Transform;

};

I know that it looks a little odd, but the utility of this should be obvious.

  David


On Fri, Jan 29, 2010 at 11:33 AM, David Gobbi <david.gobbi at gmail.com> wrote:
> I have a slightly crazy idea for vtkNew.  The only places where it
> calls any vtkObjectBase methods are in the constructor and destructor.
>  Does that mean that we could actually use vtkNew<> in our header
> files if we split vtkNew.h into a vtkNew.h and a vtkNew.txx?  We'd
> include vtkNew.h in our header files, and include vtkNew.txx (with
> definitions of the constructor and destructor) in our .cxx files.
>
> My kerthunker isn't working well enough today to convince myself that
> this would work.
>
>  David
>
>
> On Fri, Jan 29, 2010 at 10:16 AM, Brad King <brad.king at kitware.com> wrote:
>> Will Schroeder wrote:
>>> Well I have to say the vtkSmartPointer macro discussion was one of the
>>> most entertaining threads I've had the pleasure of participating in.
>>> It's good to know that after 17 years we finally know how to instantiate
>>> objects in VTK and that we are making progress :-)
>>
>> March of progress:
>>
>> 1980: C
>>    printf("%10.2f", x);
>> 1988: C++
>>    cout << setw(10) << setprecision(2) << showpoint << x;
>> 1996: Java
>>    java.text.NumberFormat formatter = java.text.NumberFormat.getNumberInstance();
>>    formatter.setMinimumFractionDigits(2);
>>    formatter.setMaximumFractionDigits(2);
>>    String s = formatter.format(x);
>>    for (int i = s.length(); i < 10; i++) System.out.print(' ');
>>    System.out.print(s);
>> 2004: Java
>>    System.out.printf("%10.2f", x);
>>
>> -----------------------------------
>>
>> 1994:
>>    vtkPolyData* pd = vtkPolyData::New();
>>    ...
>>    if(some_error)
>>      {
>>      pd->Delete(); // Hopefully we remember this one.
>>      return;
>>      }
>>    ...
>>    pd->Delete();
>> 2004:
>>    vtkSmartPointer<vtkPolyData> pd = vtkSmartPointer<vtkPolyData>::New()
>> 2010:
>>    vtkNew<vtkPolyData> pd;
>>
>> I guess we did better than formatted printing.
>>
>>> Has anyone thought about how we are going to roll this out?
>> [snip]
>>> I assume Bill and others are going to continue with experiments
>>
>> That is my understanding.
>>
>>> and if we still like it what then? We've got examples,
>>> tests, code base, tutorials, books, etc. to contend with.
>>
>> When the vtkSmartPointer<>::New() approach was added, it just slowly
>> moved into tests and examples.  It probably hasn't finished yet either.
>> Unlike vtkSmartPointer<>, vtkNew<> is useable only for local variables.
>> Perhaps its brevity and clear purpose will lead to quicker adoption.
>>
>>> My current favorite solution is to ask Brad to fix everything
>>
>> Hey, I voted for (1)!
>>
>> -Brad
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>