How to pass a static method to a constant constructor?-CodePudding

Docs says

You can use static methods as compile-time constants. For example, you can pass a static method as a parameter to a constant constructor.

But when I tried doing that, I get an error:

Minimal reproducible code:

class Foo {
  const Foo(int x);
}

class Bar {
  static int get x => 0;
  void m() => const Foo(Bar.x); // Error
}

CodePudding user response：

You need to take the documentation more literally:

You can use static methods as compile-time constants. For example, you can pass a static method as a parameter to a constant constructor.

Emphasis mine. What that means is:

class Foo {
  const Foo(void Function() func);
}

class Bar {
  static void barMethod() {}
}

void main() {
  final foo = Foo(Bar.barMethod);
}

CodePudding user response：

Thanks to @Nagual for pointing out the mistake. I was actually calling the method (and passing int) instead of passing the method itself.

This is what I should have done:

class Foo {
  const Foo(int Function() cb);
}

class Bar {
  static int getX() => 0;
  void m() => const Foo(Bar.getX); 
}