# Spellmap defaults

**🟡 Intermediate · 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](../../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/16_spellmap_defaults.py
```

```powershell
py -3.14t UX_and_AIX_experiences/02_intermediate/16_spellmap_defaults.py
```

{download}`Download this collection <../../downloads/intermediate-examples.zip>` · [Source on GitHub](https://github.com/Synaptic724/melder/blob/1211e838099a342c9dde48f064b1e772b6060e13/UX_and_AIX_experiences/02_intermediate/16_spellmap_defaults.py)

## Public surface

md.SpellMap as a constructor default

## Code

```{literalinclude} ../../downloads/02_intermediate/16_spellmap_defaults.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

- [Constructor, explicit, and collection DI](../../intermediate/dependency-injection.md)

## API contracts

- [SpellMap](../../reference/api/resolution/spellmap.md)