Possible integration with type-fest ReadonlyDeep

[rodrigofariow]

Hey there!

First of all, I would like to say that this plugin is super awesome and I'm hoping I can use it at work 🥇

At work, we make usage of type-fest, in particular ReadonlyDeep utility type.
I would like to know if the maintainers would consider a possible integration (with functional/prefer-readonly-type, for instance), through a new option, that would make use of ReadonlyDeep utility for objects, arrays, etc instead of readonly on every property.

Motivation

When using the prefer-readonly-type rule, the types declaration (mainly for objects with many properties) tend to become somewhat cluttered with all the readonly properties, e.g:

type Props = {
  readonly header?: string
  readonly subContent?: string
  readonly title?: string
  readonly modalIcon?: JSX.Element
  readonly children?: React.ReactNode
  readonly isOpen?: boolean
  readonly hideCloseIcon?: boolean
  readonly onClose?: (event: React.MouseEvent) => void
  readonly onResult?: (value: boolean) => void
  readonly rejectLabel?: string
  readonly confirmLabel?: string
  readonly buttonStyle?: ButtonProps
  readonly hideTitle?: boolean
  readonly extraClassNames?: ModalProps['extraClassNames'] & {
    readonly buttonsClassName?: string
  }
}

Using ReadonlyDeep:

type Props = ReadonlyDeep<{
  header?: string
  subContent?: string
  title?: string
  modalIcon?: JSX.Element
  children?: React.ReactNode
  isOpen?: boolean
  hideCloseIcon?: boolean
  onClose?: (event: React.MouseEvent) => void
  onResult?: (value: boolean) => void
  rejectLabel?: string
  confirmLabel?: string
  buttonStyle?: ButtonProps
  hideTitle?: boolean
  extraClassNames?: ModalProps['extraClassNames'] & {
    buttonsClassName?: string
  }
}>

I know this would somewhat couple this plugin to type-fest and the implementation might be tricky but it would provide better ergonomics to use immutable types everywhere.

Is this something that makes sense for you to add or it's 100% out of scope?

Thank you for your time :)

[RebeccaStevens]

Hey,

Currently the plain is for next major release of this plugin to address this sort of thing. However there is no time frame for when that might come out.

#259 and #317 are the start of addressing this.
I've also open an issue over on typescript-eslint that is related.

[rodrigofariow]

Hey @RebeccaStevens ,

Thanks for the quick response.
Awesome stuff, glad it has gained some traction!

Closing the issue then since it's somewhat a duplicate.

Cheers!

[RebeccaStevens]

Update: typescript-eslint/typescript-eslint#5699