Background. In STL, one requests an iterator from a container using the begin()/end() methods. In ITK, we have many potential iterator types to run across an image, so we removed the iterators from the containers (image). There is a fair amount of work to initialize an image iterator, so rather than constructing new iterators (in loops) using methods like begin()/end(), we created the GoToBegin()/IsAtEnd() methods.
Current issue. If Begin() on an iterator returns an iterator, then it should be deprecated. We'd rather people use use GoToBegin()/IsAtEnd() to be efficient. Begin()/End() should have been removed from all Image iterators long ago. But many of the other types listed (MapContainer, FixedArray, Neighborhood, ...) follow the STL paradigm more closely (where you ask a container for an iterator) and these should have Begin()/End() methods and probably should not have GoToBegin()/GoToEnd(). So in summary, Begin()/End() should be called on a container to return an iterator while GoToBegin()/IsAtEnd() should be called on an iterator to reset or test the end condition. Jim From: Insight-developers [mailto:[email protected]] On Behalf Of Williams, Norman K Sent: Friday, July 11, 2014 10:14 AM To: ITK Subject: [ITK-dev] Deprecated Begin/End in iterators? I ran into this when doing an explicit instantiation of ImageRegionIterator. Explicit instantiation will elaborate every method in a class, not just the ones that are called, so ImageRegionIterator::Begin (which is deprecated) is implemented by calling Superclass::Begin (which is also deprecated) which throws a compiler warning about the method being deprecated. My first impulse was to change the implementation to call the non-deprecated Superclass::GoToBegin, but that's kind of silly - it's probably not worth the effort to push through Gerrit. The real question is this: Why are Begin and End deprecated in the Image Region iterators, and not in all the other classes? There are a lot of classes that have Begin/End and not GoToBegin and GoToEnd: ConstShapedNeighborhoodIterator ConstSliceIterator EquivalencyTable FixedArray FixedArray ImageConstIterator ImageConstIteratorWithIndex ImageConstIteratorWithOnlyIndex ImageIterator ImageRegionConstIterator ImageRegionIterator ImageRegionReverseConstIterator ImageRegionReverseIterator ImageReverseConstIterator IndexedContainerInterface IndexedContainerInterface MapContainer MapContainer MetaDataDictionary MetaDataDictionary Neighborhood Neighborhood NeighborhoodIterator ObjectStore Point ShapedNeighborhoodIterator SliceIterator SparseFieldLayer SparseFieldLayer SpecialCoordinatesImage ThreadedIteratorRangePartitioner VectorContainer VectorContainer NarrowBand NarrowBand MultivariateLegendrePolynomial MultivariateLegendrePolynomial Histogram Histogram ImageToListSampleAdaptor ImageToListSampleAdaptor ImageToNeighborhoodSampleAdaptor ImageToNeighborhoodSampleAdaptor JointDomainImageToListSampleAdaptor JointDomainImageToListSampleAdaptor ListSample ListSample MembershipSample MembershipSample PointSetToListSampleAdaptor PointSetToListSampleAdaptor Subsample Subsample VectorContainerToListSampleAdaptor VectorContainerToListSampleAdaptor LevelSetContainerBase LevelSetContainerBase LevelSetEquationContainer LevelSetEquationContainer LevelSetEquationTermContainer LevelSetEquationTermContainer OneWayEquivalencyTable WatershedSegmentTable WatershedSegmentTable WatershedSegmentTree WatershedSegmentTree ________________________________ Notice: This UI Health Care e-mail (including attachments) is covered by the Electronic Communications Privacy Act, 18 U.S.C. 2510-2521, is confidential and may be legally privileged. If you are not the intended recipient, you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you. ________________________________
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