Question

I have interesting question. According to MSDN yield syntax:

yield return <expression>; // yield some value
yield break;               // exiting from iterator

Why not just:

yield <expression>;        // yield some value
return;                    // exiting from iterator

To me second form would be less verbose and still would have same meaning as first.
So the question is – Why first form was chosen by .NET designers ? What reasons may caused this ? What potential design problems second form has ?

Answer 1

Here’s one possibility: it would create a technical ambiguity (remember that yield is a contextual keyword, not a reserved keyword)… Unlikely, but:

struct yield {}

Then

yield x;

Is actually a variable declaration. With the “yield return x;”, that is only valid one way.

No idea if this is true. Just a thought.