CODEWITHSUNDEEP
c#linqienumerableyield
John Smith
John Smith

Reputation: 8851

Is it possible to return a list from an iterator block?

I have this function:

class Path : List<LineSegment> { }

private IEnumerable<LineSegment> GetLineSegments(CollisionType collisionType, Path path)
{
    if (collisionType == CollisionType.End)
    {
        yield return path.First();
        yield return path.Last();
    }
    else if (collisionType == CollisionType.Segment)
    {
        foreach (LineSegment lineSegment in path)
        {
            yield return lineSegment;
        }
    }
}

Basically, I am checking for collision (between ball and line) in two ways. In one case I only want to check the end points of the drawn path, but in the other case I want to return each line segment in the entire path.

It seems to be a bit weird to loop through the given list just to return the entire list. Can I just return the list? I'd like to be able to do something like this but I'm getting errors:

private IEnumerable<LineSegment> GetLineSegments(CollisionType collisionType, Path path)
{
    if (collisionType == CollisionType.End)
    {
        yield return path.First();
        yield return path.Last();
    }
    else if (collisionType == CollisionType.Segment)
    {
        return path.AsEnumerable<LineSegment>();
    }
}

Upvotes: 1

Views: 202

Answers (1)

Servy
Servy

Reputation: 203837

You have no choice but to use a foreach loop. It's a somewhat frequently requested feature, but one that is not in the language.

Upvotes: 4

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