# Config disposal and the frozen law

**🟡 Intermediate · Lesson 30**

SpellbookConfiguration, knob by knob - part 1: DISPOSAL. Two set-once properties describe teardown policy: disposal (bool) - stored flag; matched names drive calls disposal_method_names (list) - the ordered book-wide vocabulary enforce_priority_disposal_methods places the book block first when True or last when False (default). The book owns shared names in both modes. Both are IDEMPOTENT properties: set once, immutable after - the teardown story of a world must not change mid-flight. And the whole configuration FREEZES at conjure: any set_property after that refuses. Configuration is a pre-flight surface, period.

## Before you run

Use the [Intermediate guide](../../intermediate/index.md) 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

```bash
python UX_and_AIX_experiences/02_intermediate/30_config_disposal_and_the_frozen_law.py
```

```powershell
py -3.14t UX_and_AIX_experiences/02_intermediate/30_config_disposal_and_the_frozen_law.py
```

{download}`Download this collection <../../downloads/intermediate-examples.zip>` · [Source on GitHub](https://github.com/Synaptic724/melder/blob/0895ce795453cd87e35d70665957b4e89aad3317/UX_and_AIX_experiences/02_intermediate/30_config_disposal_and_the_frozen_law.py)

## Public surface

SpellbookConfiguration.set_property,
                   with_enforce_priority_disposal_methods, bind, meld, cleanup

## Code

```{literalinclude} ../../downloads/02_intermediate/30_config_disposal_and_the_frozen_law.py
:language: python
:linenos:
```

## 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.

[More intermediate examples](index.md) · [Level guide](../../intermediate/index.md)

## Related guides

- [Configuration before conjure](../../intermediate/configuration.md)

## API contracts

- [SpellbookConfiguration](../../reference/api/configuration/spellbookconfiguration.md)