Some weird obscure D syntax.

new_expressions.d

/+
  Inner classes contain a hidden field that contains a reference to the
  instance of the outer class. D has a special 'new' expression that can
  be used to create instances of inner classes and attach them to outer
  class instances.
+/

// Using printf
extern(C) int printf(char*, ...);

// Class A has a public inner class B
class A {
  // Class A has an instance variable 'x'
  int x;

  // A constructor that sets 'x'
  this(int bar) {
    x = bar;
  }

  // Inner class B
  class B{
    void foo() {
      printf("hello %d\n", x);
    }
  }
}

int main(char[][] args) {
  // Creating a new instance of A
  auto a1 = new A(42);
  auto a2 = new A(10);

  // Creating a new instance of B within the context of 'a'
  auto b1 = a1.new B;
  auto b2 = a2.new B;

  // Sweet
  b1.foo();
  b2.foo();

  return 0;
}