What functionality does the yield keyword in Python provide? For example, I'm trying to understand this code1: def _get_child_candidates(self, distance, min_dist, max_dist): if self._leftchild and distance - max_dist < self._median: yield self._leftchild if self._rightchild and distance + max_dist >= self._median: yield self._rightchild And this is the caller: result, candidates = [], [self] while candidates: node = candidates.pop() distance = node._get_dist(obj) if distance <= max_dist and distance >= min_dist: result.extend(node._values) candidates.extend(node._get_child_candidates(distance, min_dist, max_dist)) return result What happens when the method _get_child_candidates is called? Is a list returned? A single element? Is it called again? When will subsequent calls stop? 1. This piece of code was written by Jochen Schulz (jrschulz), who made a great Python library for metric spaces. This is the link to the complete source: Module mspace. Continue reading...
