ienumerator

Why does this code: public IEnumerator Test() { } Gives you an error: Error CS0161 'Test.GetEnumerator()': not all code paths return a value However this code: public IEnumerator Test() { if(false) yield return 0; } Doesn't? (and works as expected; first MoveNext() returns false) When using IEnumerators as coroutines, sometimes you want to make a coroutine (IEnumerator) that doesn't have an async operations yet (is not yielding anything) but might do that in future. From C# specification: A block that contains one or more yield statements (§8.14) is called an iterator block. Iterator blocks

I have a nested while loop inside a foreach loop where I would like to advance the enumerator indefinitately while a certain condition is met. To do this I try casting the enumerator to IEnumerator< T > (which it must be if it is in a foreach loop) then calling MoveNext() on the casted object but it gives me an error saying I cannot convert it. Cannot convert type 'System.DateTime' to System.Collections.Generic.IEnumerator via a reference conversion, boxing conversion, unboxing conversion, wrapping conversion, or null type conversion. foreach (DateTime time in times) { while (condition) { //

Is there a way to use yield blocks to implement an IEnumerator<T> which can go backward ( MoveLast() ) as well as forward? Not directly from the iterator block, no. However, the caller can always buffer the results, for example into a List<T> , or just call Reverse() - but this doesn't always apply. No, the state machine generated by the C# compiler is strictly forward. It doesn't even make sense to go backwards in many cases. Imagine an iterator reading from a network stream - to go backwards, it would have to remember everything that it had ever read, because it couldn't rewind time and ask

I have created a data structure consisting of intervals. The data structure should naturally have an enumerator that enumerates all intervals, but I would like to expose two different enumerators that enumerate the intervals in different order. One of the enumerators enumerate the intervals really fast, but in somewhat arbitrary order. The other enumerates them in lexicographical order, but a bit slower (depends on the intervals though). Depending on what you try to achieve, one enumerator might be to prefer over the other. Is there a way to allow the user to decide which enumerator should be

I have a class called GenericPermutations that is both enumerable and an enumerator. Its job is to take an ordered list of objects and iterate through each permutation of them in order. Example, an integer implemenation of this class could iterate through the following: GenericPermutations<int> p = new GenericPermutations<int>({ 1, 2, 3 }); p.nextPermutation(); // 123 p.nextPermutation(); // 132 p.nextPermutation(); // 213 // etc. So its enumerable in the sense that it contains a 'list' of things you can enumerate over. It's also an enumerator, because its job involves finding the next