[Insight-developers] ImageRandomNonRepeatingConstIteratorWithIndex segfault

[Luis Ibanez]

Hi David,

I think the real problem is to attempt to use this notation:

(A)       IteratorType it = IteratorType( image, region );

instead of using the simpler:

(B)             IteratorType it( image, region );


In (B), we call a constructor,

in (A), you call the default constructor, then the constructor
with arguments, and then the assignment operator,
all to get the same variable that you can get with (B).

----

Unfortunately, there are examples in ITK that use
the unnecessarily convoluted notation of (A).

--

BTW
The operator= that you are implementing is deceitful
in the sense that it only works in a freshly created
iterator.



     Luis


------------------------------------------------
On Sat, Feb 26, 2011 at 3:36 PM, David Doria <daviddoria at gmail.com> wrote:
> If I create this iterator with:
> itk::ImageRandomNonRepeatingConstIteratorWithIndex<ImageType>
> imageIterator(image, image->GetLargestPossibleRegion());
> everything works fine. However, if I do this:
> itk::ImageRandomNonRepeatingConstIteratorWithIndex<ImageType> imageIterator;
> imageIterator =
> itk::ImageRandomNonRepeatingConstIteratorWithIndex<ImageType>(image,
> image->GetLargestPossibleRegion());
> it segfaults on the GoToBegin() call.
> The crash is at this line of UpdatePosition():
> PositionValueType position = ( *( this->m_Permutation )
> )[m_NumberOfSamplesDone % m_NumberOfSamplesRequested];
> m_Permutation is valid (it was set when the (image, region) constructor was
> called), but m_Permutation->m_Permutation is NULL. It is valid when I create
> the iterator with the first version (above). The default constructor just
> sets everything to NULL, so I don't see any reason why calling the (image,
> region) constructor after the default constructor wouldn't work.
> Any thoughts?
> David
>
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