On this page

Spellbook configuration basics๏ƒ

๐ŸŸก Intermediate ยท Lesson 19

SpellbookConfiguration - the book's policy object. with_defaults() is easy mode; set_property tunes the knobs; conjure VALIDATES AND FREEZES it (frozen config refuses mutation - fail fast, not drift).

Before you run๏ƒ

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๏ƒ

python UX_and_AIX_experiences/02_intermediate/19_spellbook_configuration_basics.py

py -3.14t UX_and_AIX_experiences/02_intermediate/19_spellbook_configuration_basics.py

Download this collection ยท Source on GitHub

Public surface๏ƒ

md.SpellbookConfiguration, set_property, the freeze law

Code๏ƒ

 1"""
 2TIER: intermediate (19)
 3GOAL: SpellbookConfiguration - the book's policy object. with_defaults()
 4      is easy mode; set_property tunes the knobs; conjure VALIDATES AND
 5      FREEZES it (frozen config refuses mutation - fail fast, not drift).
 6SURFACE EXERCISED: md.SpellbookConfiguration, set_property, the freeze law
 7"""
 8import melder as md
 9
10
11class Service:
12    pass
13
14
15def main() -> None:
16    configuration = md.SpellbookConfiguration()
17    configuration.with_defaults()
18    configuration.set_property("phase_scheduler_workers_per_spellbook", 1)
19
20    book = md.Spellbook(configuration=configuration)
21    book.bind(spell=Service, existence="unique")
22    conduit = book.conjure()  # validates + freezes the configuration here
23    assert isinstance(conduit.meld(spell=Service), Service)
24    print("configured, conjured, melded")
25
26    try:
27        configuration.set_property("phase_scheduler_workers_per_spellbook", 8)
28        print("post-freeze mutation unexpectedly succeeded")
29    except Exception as err:
30        print("frozen configuration guards itself:", type(err).__name__)
31
32
33if __name__ == "__main__":
34    main()

Check the outcome๏ƒ

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.

More intermediate examples ยท Level guide

API contracts๏ƒ