[Insight-developers] inheritance

[Peter Cech]

On Sat, May 26, 2007 at 02:24:04 +0000, debbie larson wrote:
> Hi,
> 
> This is a basic question on inheritance but I am stuck. I wrote a class 
> that inherits from FloodFilledFunctionConditionalConstIterator. Thus in the 
> .h file I wrote
> 
> template<class TImage, class TFunction>
> class ITK_EXPORT FloodFilledFunctionConditionalConstIterator2:
>    public FloodFilledFunctionConditionalConstIterator<TImage,TFunction>
> 
> Now the parent class has several typedefs that I would like to use in the 
> child class. For example it has
> 
>   typedef typename TImage::IndexType  IndexType;
> 
> How do I use IndexType in the child class?
> 
> I tried
> 
> const IndexType & topIndex = m_IndexStack.front();
> 
> then I tried
> 
> const Superclass::IndexType & topIndex = m_IndexStack.front();

As for the type the above should work. You can do

  typedef Superclass::IndexType    IndexType

for convenience. Another thing that can go wrong is access to
Superclass' member variables. One has to access them via this->

  const Superclass::IndexType & topIndex = this->m_IndexStack.front();

This is requirement of C++ standard - AFAIK only for inheriting
templated classes, but does not hurt if you use it everywhere.

If there are still problems, post the relevant code and compiler error.

Regards,
Peter