IParserErrorMessageProvider properties must be implemented as **own** properties

[AccessViolator]

In short: in TypeScript IParserErrorMessageProvider implementation requires use of 'fat arrow' syntax, while implementation of ILexerErrorMessageProvider doesn't.
This syntax works only for ILexerErrorMessageProvider:

export class MyLexerErrorMessageProvider implements ILexerErrorMessageProvider {
  buildUnableToPopLexerModeMessage(token: IToken): string {
    return 'blah';
  }
...
}

IParserErrorMessageProvider requires fat arrow syntax to work:

export class MyParserErrorMessageProvider implements IParserErrorMessageProvider {
  buildNotAllInputParsedMessage = (options: { firstRedundant: IToken; ruleName: string }): string => {
    return 'blah';
  }
}

[bd82]

Hi @AccessViolator

Fat Arrow syntax is not required for either.

• See TypeScript Playground Example

It is true the APIs use different styles (multiple parameters vs single config object param) TBH
I do not recall why exactly is that 😄, but I'm uncertain it is a big issue...

[AccessViolator]

Well, it's not required to compile, but is required to work. Without fat arrow parser returns original messages. You should try it :)
I suppose it has smth to do with the implementation of utils.defaults()

[bd82]

Interesting point, I suppose there is an assumption that these properties exist directly on the object passed and because you implement this interface using a class rather than a plain object literal then the utils.defaults overrides those.

I will take a deeper look (hopefully on the weekend).

[bd82]

Hi @AccessViolator I finally got around to this 😄

The fix should be in 7.0.0 which will hopefully be released this weekend.
I removed the use of defaults completely, I don't think it fits well when the interface includes methods.