Hi, can someone explain the strange behaviour of c# . The output of this code below is:
"class B froma A". But more intuitive would be "class B from C". When one changes keyword override for new every things works like it supossed to (for me at least ).
using
System;namespace
ConsoleApplication1{
public class A{
public A(){
}
public virtual void Halo(C objectC){
Console.WriteLine("Class A");
}
}
public class B : A{
public B(){
}
public void Halo(A objectA){
Console.WriteLine("Class B from A");
}
public override void Halo(C objectC){
Console.WriteLine("Class B from C");
}
}
public class C : A{
public C(){
}
}
class Class1{
[STAThread]
static void Main(string[] args){
C c =
new C();B objectB =
new B();objectB.Halo(c);
Console.ReadLine();
}
}
}
Everybody fails this test: C# strange inheritance
HaseXXXXXL
Danger: language reference discussion coming :)
The answer is in section 7.4.2 and section 7.5.5.1 of the C# language spec (2nd edition)
The key point is in 7.5.5.1: "If N is applicable with respect to A (see 7.4.2.1), then all methods declared in a base type of T are removed from the set".
The definitions of N, A, and T are in the surrounding text.
Basically, if a method can be found in the derived type (compile time type, not runtime type) that matches the argument list, then the compiler does not search base classes.
ThrasherNYC
"Error CA1061 : Microsoft.Design : Change or remove B.Halo(A):Void as it hides a more specific base class method: A.Halo(C):Void."
More information about that warning can be found here:
http://msdn2.microsoft.com/en-us/ms182143.aspx
EDstyler
Tesfaye