Bug in the File.ReadLines(..) method of the .net framework 4.0

Question

This code :

IEnumerable lines = File.ReadLines(\"file path\");
foreach (var line in lines)
{
    Console.WriteLine(line); 
}
foreach (var line          


        

Answer 1

I don't know if it can be considered a bug or not if it's by design but I can certainly say two things...

1. This should be posted on Connect, not StackOverflow although they're not going to change it before 4.0 is released. And that usually means they won't ever fix it.
2. The design of the method certainly appears to be flawed.

You are correct in noting that returning an IEnumerable implies that it should be reusable and it does not guarantee the same results if iterated twice. If it had returned an IEnumerator instead then it would be a different story.

So anyway, I think it's a good find and I think the API is a lousy one to begin with. ReadAllLines and ReadAllText give you a nice convenient way of getting at the entire file but if the caller cares enough about performance to be using a lazy enumerable, they shouldn't be delegating so much responsibility to a static helper method in the first place.