How to make the function type safe?

Question

I am pretty new in Dart and I would like to know, how to make Function defined as a property more type safe:

class NewTransaction extends StatelessWidget {

  final titleController = TextEditingController();
  final amountController = TextEditingController();
  final Function addNewTx;

  NewTransaction(this.addNewTx);

With type safety I mean, that I can determine what are the inputs and outputs. Now I can pass anything to Function object.

Already answered at https://stackoverflow.com/questions/12545762/what-is-a-typedef-in-dart — Randal Schwartz, Nov 15 '20 at 22:24

score 2 · Accepted Answer · answered Nov 15 '20 at 22:36

When declaring a Function parameter, declare the return type and parameters.

In your example, I will imagine a void return type, and a String parameter. As a result:

class NewTransaction extends StatelessWidget {
  final titleController = TextEditingController();
  final amountController = TextEditingController();
  final void Function(String) addNewTx;

  NewTransaction(this.addNewTx);

}

How to make the function type safe?

1 Answers1