Equivalent C++ to Python generator pattern

Question

I\'ve got some example Python code that I need to mimic in C++. I do not require any specific solution (such as co-routine based yield solutions, although they would be acce

Answer 1

If you only need to do this for a relatively small number of specific generators, you can implement each as a class, where the member data is equivalent to the local variables of the Python generator function. Then you have a next function that returns the next thing the generator would yield, updating the internal state as it does so.

This is basically similar to how Python generators are implemented, I believe. The major difference being they can remember an offset into the bytecode for the generator function as part of the "internal state", which means the generators can be written as loops containing yields. You would have to instead calculate the next value from the previous. In the case of your pair_sequence, that's pretty trivial. It may not be for complex generators.

You also need some way of indicating termination. If what you're returning is "pointer-like", and NULL should not be a valid yieldable value you could use a NULL pointer as a termination indicator. Otherwise you need an out-of-band signal.