Zachary Turner wrote:
I can imagine the code for this might be messy. Imagine if, using boost labmda expressions, I could write:
lazylist<int> fib; fib.push_back(1); fib.push_back(1); fib.push_back(_1->prev + _1->prev->prev);
foreach(fib.begin(), fib.iter(100), cout << _1); //print the first 100 fibonacci numbers
This cannot be very efficient, nor very safe. As I said earlier, foreach(int i, make_range(1, 1) | append_rec(_1 + _2) | limit(100)) std::cout << i << std::endl; seems like a much better design to me. Actually, I've done that for some time already. This is obviously a Boost.RangeEx extension. append_rec() takes an N-ary function object and returns an adaptor that takes a range of at least N elements and returns an infinite range that applies the function object recursively. This can check at compile-time that the range has enough elements, for example. Also, it can reuse any other existing range, including one defined like this. No need for caching: the adaptor can memorize the previous N elements of a given position.