Question

I don’t have access to my dev environment, but when I write the below:

interface IExample
 void Test (HtmlControl ctrl);



 class Example : IExample
 {
     public void Test (HtmlTextArea area) { }

I get an error stating the methods in the class implementation don’t match the interface – so this is not possible. HtmlTextArea is a child class of HtmlControl, is there no way this is possible? I tried with .NET 3.5, but .NET 4.0 may be different (I am interested in any solution with either framework).

Thanks

Answer 1

interface IExample<T> where T : HtmlControl
{
    void Test (T ctrl) ;
}

public class Example : IExample<HtmlTextArea>
{
    public void Test (HtmlTextArea ctrl) 
    { 
    }
}

Note for Charles:
You can use generic to get strongly typed method, otherwise you do not need to change signature of the method in child class, but just call it with any child of HtmlControl