overriding

There have been occasions where I would want to override a method in a class with an extension method. Is there any way to do that in C#? For example: public static class StringExtension { public static int GetHashCode(this string inStr) { return MyHash(inStr); } } A case where I've wanted to do this is to be able to store a hash of a string into a database and have that same value be used by all the classes that use the string class's hash (i.e. Dictionary, etc.) Since the built-in .Net hashing algorithm is not guaranteed to be compatible from one version of the Framework to the next, I want

This code: abstract class C { protected abstract void F(D d); } class D : C { protected override void F(D d) { } void G(C c) { c.F(this); } } Generates this error: Cannot access protected member 'C.F(D)' via a qualifier of type 'C'; the qualifier must be of type 'D' (or derived from it) What in the world were they thinking? (Would altering that rule break something?) And is there a way around that aside from making F public? Edit: I now get the reason for why this is (Thanks Greg ) but I'm still a bit perplexed as to the rational; given: class E : C { protected override void F(D d) { } } Why

Is there is any reason to make the permissions on an overridden C++ virtual function different from the base class? Is there any danger in doing so? For example: class base { public: virtual int foo(double) = 0; } class child : public base { private: virtual int foo(double); } The C++ faq says that it is a bad idea, but doesn't say why. I have seen this idiom in some code and I believe that the author was attempting to make the class final, based on an assumption that it is not possible to override a private member function. However, This article shows an example of overriding private

Possible Duplicate: C++ overload resolution I ran into a problem where after my class overrode a function of its base class, all of the overloaded versions of the functions were then hidden. Is this by design or am I just doing something wrong? Ex. class foo { public: foo(void); ~foo(void); virtual void a(int); virtual void a(double); }; class bar : public foo { public: bar(void); ~bar(void); void a(int); }; the following would then give a compile error saying there is no a(double) function in bar. main() { double i = 0.0; bar b; b.a(i); } In class bar, add using foo::a; This is a common