List of generic interfaces
c#, generics, interface
Solution
You can certainly declare:
public IDataElement<T>[] GetData<T>()
and
public IDataElement<object>[] GetData()
although the latter probably isn't what you're after (your interface won't be variant even in C# 4 as it uses `T` in both an input and an output position; even if it were variant, you wouldn't be able to use that variance for value types). The former will require the caller to specify `<T>`, e.g.
`foo.GetData<string>();`
Is that okay for you?
There's no way of expressing "a collection of object, each of which implements `IDataElement<T>` for a different T" unless you also give it a nongeneric base class, at which you could just use `IList<IDataElement>`. In this case the nongeneric `IDataElement` could have the `DataElement` property, leaving the `Value` property in the generic interface:
public interface IDataElement
{
int DataElement { get; set; }
}
public interface IDataElement<T> : IDataElement
{
T Value { get; set; }
}
Is that useful in your particular situation?
It's not clear how you'd want to use a collection of data elements without knowing their types... if the above doesn't help you, maybe you could say more about what you expected to do with the collections.
Problem
If I have a generic interface with a couple of implementing classes such as: ``` public interface IDataElement<T> { int DataElement { get; set; } T Value { get; set; } } public class IntegerDataElement : IDataElement<int> { public int DataElement { get; set; } public int Value { get; set; } } public class StringDataElement : IDataElement<String> { public int DataElement { get; set; } public String Value { get; set; } } ``` Is it possible to pass a collection of the implementing classes of differing types, without having to resort to passing as object. It does not appear to be possible to define a return values as ``` public IDataElement<T>[] GetData() ``` or ``` public IDataElement<object>[] GetData() ``` Any suggestions?