Re: [Boost-users] [fusion] transform & iterators

On Thursday 11 March 2010 11:39:10 Steven Watanabe wrote:

...

Ugh. That makes things difficult then. There's no simple way to define a function that just takes a pair of iterators and does something with them. Surely others have tried to do things like this before. What's the typical solution?

Use a recursive function template or use one of fusion's algorithms.

But the non-compiling example in the first testcase shows that a fusion algorithm doesn't provide a general solution. The sequence could be the result of an application of transform() or some other algorithm that causes problems. Unless there's some other technique I've missed. In any case, I wasn't completely clear about what my goal is. Ultimately I'd like to initialize a class with a pair of iterators: struct foo { vector<int> data; template<typename InputIterator> foo(InputIterator begin, InputIterator end) : data(begin, end) {} }; foo could be initialized from many different kinds of sources: vector<int> mydata; foo f(mydata.begin(), mydata.end()); fusion::vector mydata(1,2,3,4); foo f(fusion::begin(mydata), fusion::end(mydata)); Unfortunately, it appears this isn't possible and foo will need at least two constructors: struct foo { vector<int> data; template<typename InputIterator> foo(InputIterator begin, InputIterator end) : data(begin, end) {} template<typename Sequence> foo(Sequence d) { // Some fusion algorithm } }; But that doesn't seem to be a general solution either due to the transform() problem described above. -Dave