How to pass a function onto a generic function parameter in Flutter?

Question

For example, I have this function parameter:

class MyClass {

  U Function<T, U>(T data) callback;
  MyClass ({ this.callback }) : super();

}

var int Function(String value) func = (String value) => int.parse(value);
MyClass(callback: func); // error

The error is:

The argument type 'int Function(String)' can't be assigned to the parameter type 'U Function<T, U>(T)'.

How can I make this work?

EDIT:

Based on Shubhamhackz's answer, I conclude that the only thing wrong with my code is that because the generics are on the variables and not on the function parameters, and the variables are created when the class is declared and instantiated. I should put the <T, U> on the class declaration itself, and not on the function variable declaration. So the class declaration becomes like this:

class MyClass<T, U> {

  U Function(T data) callback;
  MyClass ({ this.callback }) : super();

}

question from:https://stackoverflow.com/questions/65896146/how-to-pass-a-function-onto-a-generic-function-parameter-in-flutter

Answer 1

To declare a generic function parameter and pass it as argument. This is the way how I would implement it in dart.

typedef Callback<T,U> = U Function(T data);

void main() {
  Callback<String,int> func = (String value) {
    return int.parse(value);
  };
  MyClass(callback: func); 
}

class MyClass {

  Callback<String,int> callback;
  MyClass ({ this.callback }) : super() {
    print('MyClass Called');
  }
  
}

Output :

MyClass Called