Flutter - Parameter Type for a Method

Question

I am working a FLUTTER project and need to write a method (or maybe a function). One of the parameters in the method needs to be an expression like:

PlayList videos = videoList[index] as PlayList

Is it possible? If so what type should I should use.

Answer 1

• typedef can set the data type, method parameters

typedef ProcessCallback = PlayList Function();

• set as method parameter

void foo(ProcessCallback callback) {
   /// result type is PlayList
   var result =  callback.call();
}

• when calling the foo method

 ProcessCallback callback = () => videoList[index] as PlayList;
 foo(callback);

• Before actually running the callback.call() method, it is just a data type: Closure: () => PlayList
• .call() can also be replaced with ();