I agree with not forcing an execution model on your callers, if you can avoid it. I also try to extend the rule to be as flexible as possible for callers. For e

I agree with not forcing an execution model on your callers, if you can avoid it. I also try to extend the rule to be as flexible as possible for callers. For example, in C++, I don't like to see a function that returns a container. I prefer a function that accepts an output iterator as a parameter.