[DISABLED] Lint to prefer using a public final field instead of a private field with a public getter (Style Guide)

[pq]

From the style guide:

PREFER using a public final field instead of a private field with a public getter.

If you have a field that outside code should be able to see but not assign to (and you don’t need to set it outside of the constructor), a simple solution that works in many cases is to just mark it final.

GOOD:

class Box {
  final contents = [];
}

BAD:

class Box {
  var _contents;
  get contents => _contents;
}

[zoechi]

This rule makes only sense when the field is set directly from an argument passed in with every constructor (this.xxx or constructor initialzer list). Otherwise the linter just complaints about every field which is read-only in the public interface but writeable in the private interface. I can't see anything bad about it in the later case.

[pq]

@zoechi 👍 In fact, the advice "Make it final" would be inapplicable (since it wouldn't compile).

[pq]

Opened corresponding bug: #57183.

[pq]

Disabled pending fix of #57183.

[xxgreg]

One way you could make this lint simpler - and not have to scan the entire library for member access is:

• Make the lint optional, and disabled by default.
• Introduce an annotation @shared.
• When the lint is enabled, assume all members that aren't annotated with shared are class private.
• Don't lint members annotated as shared.

You could also add another lint which checks for accidental usage of class private members. (i.e. members which are not annotated as shared)

I'm not sure if this level of strictness would be useful practise. But I'm sure some people, especially those coming from C# or Java would like to use it.

Writing helper code to scan an entire library for member usage will be helpful for other lints, so in the long run it's probably worth doing this correctly anyway.

[hankyusa]

I didn't realize this issue existed when I created dart-lang/site-www#2971.

[pq]

If we want to pursue this, let's start with a fresh proposal.