Using IEnumerable and GetEnumerator

[Magnus.Moraberg]

Hi,

I have the following class snippet -

public class ResultsForTestCases : IEnumerable
{
public int Length
{
get { return resultsForTestCases.Length; }
}

IEnumerator IEnumerable.GetEnumerator() { return
resultsForTestCases.GetEnumerator(); }
ResultsForTestCase[] resultsForTestCases;
}

The problem though is if resultsForTestCases is null, then
resultsForTestCases.GetEnumerator() and indeed Length will fail. How
should I handle this.

Thanks,

Barry

 

[Marc Gravell]

Well, what do you want it to do? Personally, I suspect the simplest
option is to default the array to an empty array, perhaps one shared
by all instances (to avoid lots of zero-length arrays):

static readonly ResultsForTestCase[] EmptyCases = new
ResultsForTestCase[0];
ResultsForTestCase[] resultsForTestCases = EmptyCases;

Otherwise, you have to check for null and return 0 (for length) and
perhaps an empty enumerator (such as EmptyCases.GetEnumerator()) if it
is null.

Marc