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Spellmap defaults๏
๐ก Intermediate ยท Lesson 16
SpellMap - the declarative DI placeholder. As a constructor DEFAULT it declares exactly which spell fills the parameter, including frame + binding_name targeting. Exactly-one law: ambiguous or missing targets fail at conjure, not at runtime.
Before you run๏
Use the Intermediate guide for prerequisite concepts. Run from a checkout with Melder installed and Python 3.14 free-threading selected. The collection download includes the level's local helper modules.
Run the saved script๏
python UX_and_AIX_experiences/02_intermediate/16_spellmap_defaults.py
py -3.14t UX_and_AIX_experiences/02_intermediate/16_spellmap_defaults.py
Public surface๏
md.SpellMap as a constructor default
Code๏
1"""
2TIER: intermediate (16)
3GOAL: SpellMap - the declarative DI placeholder. As a constructor
4 DEFAULT it declares exactly which spell fills the parameter,
5 including frame + binding_name targeting. Exactly-one law:
6 ambiguous or missing targets fail at conjure, not at runtime.
7SURFACE EXERCISED: md.SpellMap as a constructor default
8"""
9import melder as md
10
11
12class PrimaryStore:
13 label = "primary"
14
15
16class Consumer:
17 def __init__(self, store=md.SpellMap(PrimaryStore)) -> None:
18 self.store = store
19
20
21def main() -> None:
22 book = md.Spellbook()
23 book.bind(spell=PrimaryStore, existence="unique")
24 book.bind(spell=Consumer, existence="unique")
25 conduit = book.conjure()
26
27 consumer = conduit.meld(spell=Consumer)
28 assert isinstance(consumer.store, PrimaryStore)
29 print("SpellMap default resolved:", consumer.store.label)
30
31
32if __name__ == "__main__":
33 main()
Check the outcome๏
The script contains its own assertions or demonstrated refusal paths. Run it to evaluate those checks against your installed version. The code above is taken directly from the saved file; no run output is invented here.