Question

I am creating a control that receive in datasource a DataSet or List

How i convert a IEnumerable to List in a CreateChildControls event?

protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
{
    if (dataSource is System.Data.DataSet)
    {
    }
    else if(dataSource is IList)
    {
    }
}

Answer 1

Usually one would use the IEnumerable<T>.ToList() extensionmethod from Linq but in your case you can not use it (right away) because you have the non-generic IEnumerable interface. Sou you will have to cast it first (also using Linq):

datasource.Cast<object>().ToList();

No matter what you original collection actually ist, this will always succeed.