Readonly instances cannot have private members

[parzh]

TypeScript Version: 2.8.1

Search Terms: Readonly, freeze, Object.freeze, private

Code

There is a practice to freeze instances in the constructor, right before returning them. But, unfortunately current implementation of the Readonly interface makes it impossible to do so, if there are private instance members of any kind, be it fields, accessors or methods.

class Thingy {
  private doubleIt() {
    return this.value * 2;
  }

  constructor(public value: number) {
    return Object.freeze(this); // Property 'doubleIt' is missing in type 'Readonly<this>'
  }
}

This enforces developers to use workarounds and local usage conventions.

Expected behavior:
No compile errors.

Actual behavior:
Compile error: Property 'squareIt' is missing in type 'Readonly<this>'

Playground Link

Related Issues:
#22315

[ghost]

I'll mark this as a duplicate of #10725 -- although we should probably not have used Readonly in that case since as you can see it doesn't work.

[parzh]

I see the referenced issue as related to this one, rather than duplicate of it.

You're talking about Object.freeze() returning Readonly? No, I think, that's fine. The strange part is that readonly can be applied to properties only, – that's strange IMO. I mean, methods too in principle may or may not be read-only. Not sure about getters and setters though

[ghost]

See #16441.