# Fx.Fx.Class

The constructible service class returned by `Fx.Service`.

## Signatures

```ts
interface Class<Self, Id extends string, A, E> extends Service<Self, Id, A, E> {
    new (): Service<Self, Id, A, E>;
}
```

## Why

A single value can act as the service tag, the service-backed `Fx`, and the owner
of its [Layer](https://effect.website/docs/v4/api/effect/Layer) constructor,
matching Effect's class-based service ergonomics.

## Ownership and lifetime

Constructing the class returns the class value and starts no producer. Installed
layer scopes own actual implementations.

## Construct signatures

Returns the service class as its service-backed `Fx` value.

## Construct signatures: Why

Supports Effect's class-as-tag ergonomics without allocating wrapper instances.

## Construct signatures: Ownership and lifetime

Construction starts no producer. The installed layer owns the implementation.

## Examples

```ts
import { Fx } from "@typed/fx"
import type { Fx as FxModel } from "@typed/fx/Fx"

class Ticks extends Fx.Service<Ticks, number>()("app/Ticks") {}
const definition: FxModel.Class<Ticks, "app/Ticks", number, never> = Ticks
```