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Registration hooks๏
๐ก Intermediate ยท Lesson 03
Hooks ride the registration, not the call site - pre, activation, and post hooks attach through the fluent chain and fire around instance creation. The printed order IS the documentation; the 3.14t run records the exact firing points.
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/03_registration_hooks.py
py -3.14t UX_and_AIX_experiences/02_intermediate/03_registration_hooks.py
Public surface๏
md.SpellBinder.with_pre_hook / with_activation_hook / with_post_hook
Code๏
1"""
2TIER: intermediate (03)
3GOAL: Hooks ride the registration, not the call site - pre, activation,
4 and post hooks attach through the fluent chain and fire around
5 instance creation. The printed order IS the documentation; the
6 3.14t run records the exact firing points.
7SURFACE EXERCISED: md.SpellBinder.with_pre_hook / with_activation_hook /
8 with_post_hook
9"""
10import melder as md
11
12EVENTS: list[str] = []
13
14
15class Engine:
16 def __init__(self) -> None:
17 EVENTS.append("engine constructed")
18
19
20def note(stage: str):
21 def hook(*args: object, **kwargs: object) -> None:
22 EVENTS.append(stage)
23 return hook
24
25
26def main() -> None:
27 book = md.Spellbook()
28 md.SpellBinder(book).bind(Engine) \
29 .as_unique() \
30 .with_pre_hook(note("pre")) \
31 .with_activation_hook(note("activation")) \
32 .with_post_hook(note("post")) \
33 .finalize()
34
35 conduit = book.conjure()
36 engine = conduit.meld(spell=Engine)
37 assert isinstance(engine, Engine)
38 assert "engine constructed" in EVENTS
39 print("lifecycle event order:", " -> ".join(EVENTS))
40
41
42if __name__ == "__main__":
43 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.