使用显式接口实现

Question

I am trying to change the property type in interface implementation class using explicit interface implementation.

interface ISample
{    
   object Value { get; set; }     
} 

class SampleA : ISample
{    
   SomeClass1 Value { get; set; } 

   object ISample.Value
    {    
        get { return this.Value; }
        set { this.Value = (SomeClass1)value; }
    }    
}


class SampleB : ISample
{

   SomeClass2 Value { get; set; } 

   object ISample.Value
    {    
        get { return this.Value; }
        set { this.Value = (SomeClass2)value; }    
    }    
}

class SomeClass1
{    
   string s1;    
   string s2;    
}

But when I need to pass in interface obj in a function, I cant access the objects of SomeClass1 or SomeClass2.

For eg:

public void MethodA(ISample sample)    
{    
  string str = sample.Value.s1;//doesnt work.How can I access s1 using ISample??    
}

I don't know if this is understandable, but I cant seem to get an easier way to explain this. Is there a way to access the properties of SomeClass1 using interface ISample?

Thanks

Answer 1

That is because you've received the object as the interface, so it doesn't know about the class's new property type. You would need to:

public void MethodA(ISample sample)
{
  if (sample is SampleA)
  {
    string str = ((SampleA)sample).Value.s1;
  }     
}

A better solution might be to use the visitor pattern - which would have implementations for handling the different ISample's.