Question

I have the following Enum:

Public Enum myEnum As Integer  
    first = &H1
    second = &H2
    third = &H4
    fourth = &H8
    fifth = &H10
    sixth = &H20
End Enum

It is neccessary, unfortunately, that the enum elements have those values, or at least have values that can be binary compared.

I have a class which can be set during construction to be one of two types, a type with values relating to first through fourth, and a second type with values relating to first through sixth.

I would like to use a For loop to iterate through 1-4 or 1-6 elements of the enum, but I have found that this code:

For enumType as myEnum = myEnum.first to myEnum.fourth
Next

iterates through {1,2,3,4,5,6,7,8} and not through {1,2,4,8}.
This is not ideal.

Obviously I can code around this issue, but I can see a scenario where that workaround could be easily missed in maintenance programming, and I’m hoping someone can recommend a simple solution that won’t break if, for example, the values in the enum have to change at a later date.

Answer 1

Sorry for C#:

static IEnumerable<T> EnumRange<T>(T begin, T end)
{
    T[] values = (T[])Enum.GetValues(typeof(T));
    int beginIndex = Array.IndexOf(values, begin);
    int endIndex = Array.IndexOf(values, end);

    for(int i = beginIndex; i <= endIndex; ++i)
        yield return values[i];
}

foreach(MyEnum e in EnumRange(MyEnum.First, MyEnum.Fourth)
    // Code goes here