Hashtable.Keys.CopyTo() when hashtable is empty throws ArgumentException

My CodeSmith-generated hashtable throws an exception in a case when Hashtable does not.

I believe this problem can be fixed by changing the implementation of the CheckTargetArray method in Hashtable.cst as follows:

Change this line:

if (arrayIndex >= array.Length)
throw new ArgumentException(
"Argument must be less than array length.", "arrayIndex");

to the following:

if ((arrayIndex >= array.Length) &&
((arrayIndex != 0) || (array.Length != 0)))
throw new ArgumentException(
"Argument must be less than array length.", "arrayIndex");

Kyle Blaney

Kyle,

I will pass this on to Chris. He is the maintainer of these collection templates.

Thanks,
Eric J. Smith

Note that the same problem occurs with a CodeSmith generated ArrayList. For example, the following code throws an ArgumentException when it should not:

IntArrayList intArrayList = new IntArrayList();
int[] intArray = new int[0];
intArrayList.CopyTo( intArray );

This problem can be fixed by making the same modifications to the CheckTargetArray method as detailed above.

Sorry for the late reply, I'm rather busy these days and won't be able to produce a fix right away.

Actually I was a bit doubtful at first if a fix was needed at all. CopyTo(array, index) is an ICollection method whose MSDN documentation clearly states that it SHOULD throw an ArgumentException if "index is equal to or greater than the length of array". If array is empty, an index of zero is illegal according to that rule.

So you might argue that the template is correct and the Microsoft class is wrong!

However, you have a good point with ArrayList.CopyTo(array). This one shouldn't throw if array is empty as long as the ArrayList is empty, too.

Seeing that I'll have to fix this anyway I'll reproduce Microsoft's undocumented ICollection.CopyTo behavior as well, in all the templates, as soon as I get around to it.

Fixed in the latest version 1.5.1 for all templates. Thanks for reporting!