.NET (Core and Framework)

Hendrik Debedts wrote:

I know

Hendrik Debedts wrote:

but what is the need of doing this? Why should someone do this?

<br />
{<br />
    if ( i is A ) { (A) i = blah blah blah }<br />
    else<br />
        if ( i is B ) { (B) i = blah blah blah }<br />
        else throw something perhaps<br />
}<br />

<br />
A a = new A() ; <br />
F ( (I) a ) ; // legal, but needless<br />
F ( a ) ; // prefered<br />

PIEBALDconsult wrote:

You wouldn't cast a class to an interface, it's unnecessary

public interface IList {
   public void Add(object x);
}
 
public interface IDictionary {
   public void Add(object x);
}
 
public class Test : IDictionary, IList {
}
 
Test t = new Test();
((IList)t).Add(x);
((IDictionary)t).Add(x);

PIEBALDconsult wrote:

But then you're probably getting into the reason C# only supports single inheritance.

Hendrik Debedts wrote:

when the class implements the interface you don't have firstly cast the object to the interface

Hendrik Debedts wrote:

Here you pass an object of a class who implements the System.Collections.ICollection interface (Person) to a method that has a System.Collections.ICollection attribute (static void aMethod(System.Collections.ICollection i))