GeezerVison

To allow an instance of your Dart class to be called like a function, implement the call() method.

The call() method allows an instance of any class that defines it to emulate a function. This method supports the same functionality as normal functions such as parameters and return types.

In the following example, the WannabeFunction class defines a call() function that takes three strings and concatenates them, separating each with a space, and appending an exclamation. Click Run to execute the code.

class WannabeFunction {
  String call(String a, String b, String c) => '$a $b $c!';
}

var wf = WannabeFunction();
var out = wf('Hi', 'there,', 'gang');

void main() => print(out);