Lecture.md

Dictish

Design Goals

• Implement a dict-like object without relying on dict.
• Implement enough of dict's behaviour to make it useful.
• Avoid mutation.
• Extend the functionality beyond what's available in dict in Python 3.8.
  • Supporting merging two dictish through or:ing them (d | other).
  • Supporting appending to a dictish by add:ing to it (d + key_value_pair).
  • Behaving like a function (callable).
  • Supporting subset and superset comparisons of two dictish.

Tutorial Steps

1. Basic, empty dictish.
2. Basic dictish with key-value pairs.
3. Iterating over keys, values, and items.
4. Supporting subscript (d["key"]).
5. Supporting get (d.get("key")).
6. Equality.
7. Deduplicating key-value pairs.
8. Supporting | and +.
9. Representation (repr and str).

Going Further

10. Hello doctests!
11. Extracting a helper collection class.
12. A bit of inspiration taken from Clojure.
13. Subset and superset comparisons.

Stretch Goals

14. A word on hashing.
15. A word on Abstract Base Classes.