How do I call a super constructor in Dart?

Question

How do I call a super constructor in Dart? Is it possible to call named super constructors?

Answer 1

Yes, it is, the syntax is close to C#, here is an example with both default constructor and named constructor:

class Foo {
  Foo(int a, int b) {
    //Code of constructor
  }

  Foo.named(int c, int d) {
    //Code of named constructor
  }
}

class Bar extends Foo {
  Bar(int a, int b) : super(a, b);
}

class Baz extends Foo {
  Baz(int c, int d) : super.named(c, d);  
}

If you want to initialize instance variables in the subclass, the super() call must be last in an initializer list.

class CBar extends Foo {
  int c;

  CBar(int a, int b, int cParam) :
    c = cParam,
    super(a, b);
}

You can read about the motivation behind this super() call guideline on /r/dartlang.