multiple-inheritance

问题 Here is an example of multiple inheritance. I used the scope resolution operator to resolve the ambiguity instead of a virtual class. struct A { int i; }; struct B : A {}; struct C : A {}; struct D: B, C { void f() { B::i = 10; } void g() { std::cout << B::i <<std::endl; } }; int main() { D d1; d1.f(); d1.g(); return 0; } Is B::i well-formed? 回答1: Is B::i well-formed? Yes, it is. The most pertinent reference is [class.qual]/1: If the nested-name-specifier of a qualified-id nominates a class,

问题 I was pretty sure that the answer to that question was, "Never, ever can a template be the copy constructor." Unfortunately, I just spent 3 hours figuring out why I was getting a warning about recursion, tracked it to the copy constructor, watched the debugger go insane and not let me look at the recursive code, and finally tracked it down to a missing '&' in a base constructor. You see, I have this complex policy-based design host that's been working fine for a while now. I went about

问题 If I run this code, I'v got the subject error message. But why? And how to avoid it getting the C class having its parents slots? class A(): __slots__ = ['slot1'] class B(): __slots__ = ['slot2'] class C(A, B): __slots__ = [] 回答1: Simply speak, you just cannot do it. As stated in Documentation, Multiple inheritance with multiple slotted parent classes can be used, but only one parent is allowed to have attributes created by slots (the other bases must have empty slot layouts) - violations

问题 I need help for an implementation that uses multiple inheritance of Interfaces... There is an existing code whith an interface which has a lot of functions. The instances are created using a factory. class IBig { // Lot of pure virtual functions }; And his inplementation: class CBig: public IBig { // Implementation } I Want to split the interface in multiple smaller interfaces, but it should stay compatible to the existing code for some time. Here is a sample of what I tried to do: class

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . It is said, that Java language support single inheritance only. However how is it possible to inherit from Object and from any other

问题 Suppose you have two classes X & Y. You want to decorate those classes by adding attributes to the class to produce new classes X1 and Y1. For example: class X1(X): new_attribute = 'something' class Y1(Y): new_attribute = 'something' new_attribute will always be the same for both X1 and Y1. X & Y are not related in any meaningful way, except that multiple inheritance is not possible. There are a set of other attributes as well, but this is degenerate to illustrate. I feel like I'm

问题 In my C# code I want a CustomIdentity class that inherits from System.MarshalByRefObject and System.Security.Principal.GenericIndentity classes. However when I try to write such inheritance C# would object with CS1721 error saying I can't directly inherit from more than one class. Now in this case it's quite easy to overcome this - I'll inherit from IIdentity , add GenericIdentity member variable and reimplement all IIdentity methods via that member variable. But how would I do in case I

问题 (Please note: knowledge of the trading card game Magic: The Gathering will be a plus here. Sorry, I don't know how to put it any easier.) I have hit upon a problem using Java , which I'll describe as follows... I have a fundamental class called Card with all the following attributes: public class Card{ String Name; String RulesText; String FlavorText; String Cost; int ConvertedCost; String Rarity; int Number; } The Permanent class extends Card, and is extended in turn by the classes Creature,

问题 I got some warnings by using pure virtual interfaces on some MFC CWnd derived objects through multiple inheritance. I believe it's caused by defining the methods which need to be implemented for the message map. warning C4407: cast between different pointer to member representations, compiler may generate incorrect code That sounds like a bit more than a warning, more like something that might cause heap corruption. So is there another way to do something similar to below that won't cause the

问题 What I am looking to do is develop two different base classes which should not be inherited together in the one derived class. Is there any way I can enforce this at compile time? class Base1 {}; class Base2 {}; class Derived1 : public Base1 {} // OK! class Derived2 : public Base2, public Other {} // OK! class Derived3 : public Base1, Base2 {} // Can I force the compiler to complain? Derived1 d1; // OK! Derived2 d2; // OK! Derived3 d3; // Or can I force the compiler to complain here? I'm