External iterators: for language bindings #33
Description
The current handlegraph api, uses the internal iterator approach (e.g. for_each_edge etc.) This is very inconvenient when trying to use this code from python. The only way to move data from inside the iteratee to the outside is by running the iteration in a different thread than the major python code and pass out the required information using a shared blocking queue. As you can imagine this is a pain to program.
The python approach, like modern java is to use generators/streams instead. This works well in these languages because memory ownership is well defined. For C++ I imagine this approach was taken to make it easier to keep track of who owns what memory. Unfortunately, the push approach inherent in this solution is a pain to use from languages which like to use a pull model.
Could we have standard C++ iterators for each iteratee method?