Migration (v6 to v7)

v7 is a major release. The decorator surface changed. Everything else (the Envapter readers, converters, sources, and types) is unchanged and stays on envapt.

Decorators are now TC39 accessor decorators

The default @Envapt import, and the sugar decorators, is now a TC39 Stage 3 accessor decorator. It needs no experimentalDecorators flag and runs on any runtime, including Bun and Deno executing a .ts file directly.

Declare the field with the accessor keyword. Static fields use static accessor x: T, instance fields use accessor x!: T with the definite-assignment !.

// v6 (legacy form)
import { Envapt, Converters } from 'envapt';

class Config {
    @Envapt('PORT', { converter: Converters.Number, fallback: 3000 })
    static readonly port: number;
}

// v7 default (accessor form, no experimentalDecorators)
import { Envapt, Converters } from 'envapt';

class Config {
    @Envapt('PORT', { converter: Converters.Number, fallback: 3000 })
    static accessor port: number;
}

For an instance field, the change is from declare readonly x: T to accessor x!: T.

Keeping the legacy decorators

If you cannot switch to the accessor form yet, the v6 decorators move to the envapt/legacy subpath. They keep the static readonly / declare readonly form and still need experimentalDecorators.

// keep the v6 behavior
import { Envapt, Converters } from 'envapt/legacy';

class Config {
    @Envapt('PORT', { converter: Converters.Number, fallback: 3000 })
    static readonly port: number;
}

Only the decorators move. Envapter, Converters, the sources, and the types stay on envapt. A module that imports decorators only from envapt/legacy must also import 'envapt' once so the runtime source binds.

Decorated properties are read-only

Assigning to a decorated property now throws EnvaptError. Till v6 the legacy decorator installed only a getter, so an assignment was a silent no-op in sloppy mode or a native TypeError in strict mode. Both the default and legacy forms throw the clearer error in v7.

Decorated fields are typechecked

The decorator checks the decorated field's declared type against the converter's output. A field that cannot hold the value is a compile error, [envapt] field type must hold the converter output. A no-fallback read can be null, so a field that compiled as static readonly port: number for @EnvNum('PORT') on v6 now needs number | null (or static accessor port: number | null in the modern form). This check applies to both the modern and legacy decorators.