If I may hazard a guess (I don't know why the original code used it), Python dictionaries are also ordered (and there's no option in Python's library to have them not ordered). Maybe they wanted to match Python's behavior.
Python dicts are ordered in a slightly weird way though, and only since 3.6 (before that it leaked the hashtable implementation scheme). Std::map orders things by some boolean comparator (and duly goes wrong if you give it a partial order comparison), binary tree style. Python currently orders by insertion order, very like storing a list of the keys as well as a hash table, so it can iterate over it in insertion order. That's definitely slower than not maintaining that order but it seems popular with python developers.
Do you mean "insertion ordered"? That means the order of iteration is guaranteed to match insertion order. C++'s std::map is ordered by key (less than comparison) to create a binary search tree. So iteration order will always be ordered by key value. C++'s std::unordered_map has no ordering guarantees (that I know). I don't think the standard C++ template library has the equivalent of a modern Python dict, nor Java LinkedHashMap. Does anyone know if that is incorrect?
