是否可以在 dart 中使用 getter 作为 function 参数？

Question

I have a repetitive function like this:

repetitiveFunction(Type type) async* {
  yield* _recordCollectionQuery(type)
    .snapshots()
    .map((snapshot) {
      final List<Record> records = snapshot.docs
        .map((doc) => RecordDto.fromFirestore(doc).toDomain())
        .toList();
    // Here instead of using "record1.number", I want to use parameter like "record1.param"
    records.sort((record1, record2) => record2.number.compareTo(record1.number));
    return records;
  });
}

Here Record class is freezed data class. I have to use this function multiple times just changing record.number , here number is a getter of Record class. So can I use this getter as a function parameter?

Answer 1

You can't directly use getters/setters as functions since the point of getters/setters is to be indistinguishable from member variables.

You instead can easily wrap the getters in anonymous functions (eg (record) => record.number) , and you then can supply different anonymous functions for different getters:

Here's a concrete example:

Stream<List<Record>> repetitiveFunction(
  List<Record> records,
  Comparable Function(Record) getComparableProperty,
) async* {
  yield* _recordCollectionQuery(type).snapshots().map((snapshot) {
    final List<Record> records = snapshot.docs
        .map((doc) => RecordDto.fromFirestore(doc).toDomain())
        .toList();
    records.sort((record1, record2) => getComparableProperty(record2)
        .compareTo(getComparableProperty(record1)));
    return records;
  });
}