Question

I have the following class which uses BinaryReader internally and implements IDisposable.

 class DisposableClass : IDisposable     {         private BinaryReader reader;         public DisposableClass(Stream stream)         {             reader = new BinaryReader(stream);         }          protected virtual void Dispose(bool disposing)         {             if (disposing)             {                 ((IDisposable)reader).Dispose(); //                reader.Dispose();// this won't compile             }         }          public void Dispose()         {             this.Dispose(true);         }     } 

I have already figured out that I need to cast BinaryReader to IDisposable to be able to call Dispose on it, but I don’t understand why I can’t just call the Dispose() method directly without casting to IDisposable?

Answer 1

It won’t work because the Dispose method on BinaryReader has been explicitly implemented.

Instead of being implicitly implemented, as in:

public void Dispose() { } 

…it has been explicitly implemented, as in:

void IDisposable.Dispose() { } 

…which means it can only be accessed via the IDisposable interface. Therefore, you have to cast the instance to IDisposable first.