why do we need Callable classes in dart

Question

What is the use of callable classes in dart lang? Following is the example code available on official dart site.

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

main() {
  var wf = new WannabeFunction();
  var out = wf("Hi","there,","gang");
  print('$out');
}

How useful is it add a call function and call it using a class instead of creating a function itself in class

Answer 1

This can be useful to make "named functions":

class _Foo {
  const _Foo();

  void call(int bar) {}

  void named() {}
}

const foo = _Foo();

Which allows both:

foo(42);

and

foo.named();