Iterator blocks and yield return

Collection Classes - slide 36 : 36

Iterators are implemented by methods made with iterator blocks

IEnumerator<Type> Method() { // iterator block
  Type t;

  ...
  yield return t;
  ...
}

Characteristics
- The return type of the method must be an enumerator or an enumerable
- A method with an iterator block is not executed immediately when calling it
- Instead an enumerable object is created and returned
- Execution starts when MoveNext is activated on the enumerable object

The compiler transforms a method with an iterator block to an underlying state machine which manages the traversal

Infinite Collections of Integers