CODEWITHSUNDEEP
dart
genericUser
genericUser

Reputation: 7208

How to pass a Type parameter to a function in Dart?

I want to pass a Type parameter to my function. Is that possible?

For example:

List getSomething(Type typeToReturn) {
    return List<dynamic, typeToReturn>();
}

My code:

List<charts.Series> getSeriesData(Type typeToReturn) {
    List<DateTime> dates = getDaysInBetween(startTime, DateTime.now());
    List<Map> data = [];
    dates.forEach((DateTime date) => data.add({
          'date': '${date.day.toString()}.${date.month.toString()}',
          'score': _getTotalScoreInSpecificDate(date)
        }));

    return [
      new charts.Series<dynamic, typeToReturn>(
        id: 'Score',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (data, _) => data['date'],
        measureFn: (data, _) => data['score'],
        data: data,
      )
    ];
  }

Upvotes: 0

Views: 1226

Answers (2)

Ben Konyi
Ben Konyi

Reputation: 3229

You want to do something like this using generics, completely dropping your typeToReturn parameter:

List<charts.Series> getSeriesData<T>() {
    // ...

    return [
      new charts.Series<dynamic, T>(
        // ...
      )
    ];
  }

Also, I don't believe you can use a Type object dynamically as a type parameter. I think you can using dart:mirrors, but that library isn't compatible with Flutter and isn't really maintained anymore.

Upvotes: 3

Michael Soliman
Michael Soliman

Reputation: 2818

Yes, you can use Generics, so the function will be something like this:

List<dynamic, T> getSomething<T>(T typeToReturn) {
    return List<dynamic, T>();
}

Upvotes: 1

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