Thanks a lot. I appreciate the help :) On Fri, Mar 7, 2008 at 2:53 AM, Roman Perepelitsa < roman.perepelitsa@gmail.com> wrote:

Ashkan Aliabadi writes:

...

Dear all,I've decided to write an ABC named BasicIterator, from which

all derived iterators are to be descended. The reason being that I have to refer to iterators inside an interface and I need a general base type as a place holder to which I can refer. Besides, I don't want to use CRTP in the interface, but I don't care if I'm forced to use it inside BasicIterator.As discussed in the interoperability section of iterator_facade (here), the euqal() function must be templatized. The problem is that I have to make equal() a pure virtual member function in order to force derived types override it, but templated virtual functions on the other hand, are not valid.So I was wondering what the best approach is. How can I achieve both of these goals? Please advise.Any ideas/suggestions are welcome.Thanks in advance

You might want to take a look at any_range from oven library ( http://p-stade.sourceforge.net/oven/doc/html/oven/ranges.html#oven.ranges.an... ) or any_iterator from adobe opensource library (http://stlab.adobe.com/classadobe_1_1any__iterator.html). Both of them provide convenient way for declaring methods in interface classes that return or accept ranges of values.

HTH, Roman Perepelitsa.

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Ashkan Aliabadi writes:

Following node_iter example of iterator_facade (here), how can I wrap that

inside an any_iterator? I'm really having a hard time figuring that out. I'm using an any_iterator implementation by Thomas Becker (here). I would really appreciate it if anyone could give me a hand.Regards You should use iterator_facade to create new types of iterators (for example, if you have your own data structure and want to provide iterator based access to its elements). This is one part of the story. Another part is any_iterator. It's just an iterator that any other iterator can be convertible to. You don't need to add support for any_iterator in your own iterator (that you probably create using iterator_facade); any_iterator will just work with any iterator type (even ones from STL). Here is an example of how you can use any_iterator. #include <vector> #include <algorithm> #include <iterator> #include <iostream> #include int main() { // first type argument is value_type of // iterator. second is iterator category. typedef IteratorTypeErasure::any_iterator random_access_iterator_of_int; typedef IteratorTypeErasure::any_iterator input_iterator_of_int; std::vector<int> v; // any random access iterator with value_type = int // is convertible to random_access_iterator_of_int random_access_iterator_of_int r(v.begin()); // any input iterator with value_type = int // is convertible to input_iterator_of_int input_iterator_of_int b(v.begin()), e(v.end()); std::copy(b, e, std::ostream_iterator<int>(std::cout, "\n")); } HTH, Roman Perepelitsa