Dave Gomboc <[EMAIL PROTECTED]> writes: >> > Since you advocate elsewhere that exception classes be derived >> > from std::exception, the answer is because otherwise LSP would >> > be violated. >> >> You can't access the derived class' assignment operator through a >> pointer/reference to a polymorphic base, so that point is moot. > > Well, you're the expert on this. (I thought you could catch a reference > to an exception, dynamic_cast it downwards, then use the assignment > operator. Sure, this would be a stupid thing to do, but if possible I > certainly can imagine some few misguided souls who haven't yet grokked C++ > exception handling doing so.)
You can do it, but then LSP doesn't matter since you know the concrete type. >> LSP is weird anyway. What's the point of polymorphism if you're not >> going to change the behavior of the class in some observable way? If >> the derived class were transparently substitutable for the base class >> it wouldn't be much good, would it? > > I disagree here; "transparently substitutable" != "observable behaviour is > identical". Can you clearly define the difference? I don't think I've ever read a description of LSP which doesn't leave that question completely unaddressed. -- Dave Abrahams Boost Consulting www.boost-consulting.com _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
