Question

Is there a way to specify in an interface a known return type, but unknown number/type of parameters.

The reason I am asking is that I am using Windows Azure Table Storage and each table will have different Partition and Row keys with different input values.

I am creating a ITableOperations interface the code will be something like:

interface ITableOperations<T>
    where T : Azure.AzureTableEntity
{
    // Key specification
    string PartitionKey(/* ? What should go here  */);

    // Key specification
    string RowKey(/* ? What should go here  */);
}

And the item table… For another table, the input params would be different

public class ScheduledItem : ITableOperations<ScheduledPostEntity>
{
    public string PartitionKey(Guid userGuid)
    {
        return userGuid.ToString();
    }
    public string RowKey(DateTime dateScheduled)
    {
        return dateScheduled.ReverseTicks();
    }
}

Answer 1

C# supports multiple parameter in the form of an array by using the params keyword.

You could do this:

interface ITableOperations<T>
    where T : Azure.AzureTableEntity
{
    // Key specification
    string PartitionKey(params object[] data);

    // Key specification
    string RowKey(params object[] data);
}

If you already know the alternatives of parameters, then you can use overload.
Lets say you have a method that can either receive a string or a Guid or both, you could do this:

    string PartitionKey(Guid guid);
    string PartitionKey(string str);
    string PartitionKey(Guid guid, string str);

If you are using C# 4, then you can use optional parameters:

    string PartitionKey(Guid guid = default(Guid), string str = null);