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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 JonChesterfield 3y ago
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.
- throwaway2037 3y agoordered in a slightly weird way 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?