# Config

Configuration types and errors, plus the create function behind defineConfig.

`Config` holds `Config.create` and the types of the helpers it returns. Applications usually call it through its root alias, [`defineConfig`](/docs/api/core/defineConfig), which has the same options and inferred helpers.

```ts title="zyzz.config.ts"
import { Config } from 'zyzz'

export const { style, vars } = Config.create({
  vars: { color: { brand: '#06c' } },
})
```

## Members

[Config.create](/docs/api/core/defineConfig)

Bind style and recipe helpers to a variable set, and return the config
helpers.

## Types

* **`Config.create.Options`:** The accepted options.
* **`Config.create.ReturnType<options>`:** The helpers inferred from the options.
* **`Config.StyleFactory`:** The bound `style` function.
* **`Config.VariableConfig<options>`:** The helpers of a config with `vars`.
* **`Config.VariableOptions`:** The options of a config with `vars`.
* **`Config.VariableScope<options>`:** The bound `vars` function and reference tree.

```ts title="scoped.ts"
import type { Config } from 'zyzz'

// Accepts the `vars` helper of any config with a `color.brand` token
export function scoped(
  select: Config.VariableScope<{ vars: { color: { brand: string } } }>,
) {
  return select({ colorScheme: 'dark' })
}
```

## Errors

### Config.InvalidError

Thrown when options cannot form a configuration, such as unknown options, named sets with different paths, or invalid layer names. Its `name` is `'Config.InvalidError'`. Invalid variable values throw [`Vars.InvalidError`](/docs/api/core/namespaces/Vars#varsinvaliderror) instead.

```ts
import { Config } from 'zyzz'

// Options loaded at runtime, which TypeScript cannot check
declare const options: Config.create.Options

try {
  Config.create(options)
} catch (error) {
  if (error instanceof Config.InvalidError) console.error(error.message)
}
```