How to handle an “infinite” IEnumerable?

Question

A trivial example of an \"infinite\" IEnumerable would be

IEnumerable Numbers() {
  int i=0;
  while(true) {
    yield return unchecked(i++);
  }
}
         


        

Answer 1

As long as you only call lazy, un-buffered methods you should be fine. So Skip, Take, Select, etc are fine. However, Min, Count, OrderBy etc would go crazy.

It can work, but you need to be cautious. Or inject a Take(somethingFinite) as a safety measure (or some other custom extension method that throws an exception after too much data).

For example:

public static IEnumerable SanityCheck(this IEnumerable data, int max) {
    int i = 0;
    foreach(T item in data) {
        if(++i >= max) throw new InvalidOperationException();
        yield return item;
    }
}