multiple-inheritance

WCF class implementing two operation contracts in different service contracts with same name

由 流过昼夜 提交于 2019-12-09 16:00:57
问题 I have declared two service contracts as follows: [ServiceContract] public interface IContract1 { [OperationContract] double Add(int ip); } [ServiceContract] public interface IContract2 { [OperationContract] double Add(double ip); } I have a class which implements these two contracts. I have created two endpoints for both contracts. But I'm not able to access the service from client code. It displays a big error when I try to update the service reference as: Metadata contains an error that

Why does virtual inheritance need to be specified in the middle of a diamond hierarchy?

由 自古美人都是妖i 提交于 2019-12-09 15:28:39
问题 I have diamond hierarchy of classes: A / \ B C \ / D To avoid two copies of A in D, we need to use virtual inheritance at B and C. class A { }; class B: virtual public A {}; class C: virtual public A { }; class D: public B, public C { }; Question: Why does virtual inheritance needs to be performed at B and C, even though the ambiguity is at D? It would have been more intuitive if it is at D. Why is this feature designed like this by standards committee? What can we do if B and C classes are

Virtual Inheritance, one class enough?

由 只愿长相守 提交于 2019-12-09 15:21:58
问题 I understand the concept of virtual inheritance, but I couldn't find the answer to this anywhere. Say you have class D which inherits class B and C. Both B and C inherit class A. So you could make B and C virtually inherit A to avoid two instances of A. But do you have to specify virtual inheritance at both B and C or does it already create only one instance of A if one of the two virtually inherits A and the other doesn't? Thanks 回答1: They must all be virtual . From C++11 10.1 [class.mi]/7:

Cooperative multiple inheritance issue

由 陌路散爱 提交于 2019-12-09 12:21:40
问题 This is an extension to this question and raises a problem, which you, my fellow StackOverflowers, will hopefully be able to help me with. From the referenced question, consider the final code sample: class A(object): def __init__(self): print "entering A" print "leaving A" class B(object): def __init__(self): print "entering B" super(B, self).__init__() print "leaving B" class C(A,B): def __init__(self): print "entering c" super(C, self).__init__() print "leaving c" As noted by the poster,

Parallel Inheritance between Interface Classes and Implementation Classes in C++

由 为君一笑 提交于 2019-12-09 12:18:48
问题 I'm trying to use C++ abstract base class in the way similar with Java interface. Supposed that we have following interface classes with only pure virtual functions: class Shape { virtual double area()=0; }; class Square : public Shape { virtual void setLength(double length)=0; }; class Rectangle : public Square { virtual void setWidth(double width)=0; }; and I try to implement Square and Rectangle the following way: class SquareImpl : public Square { /*implementation*/ }; class RectangleImpl

Implementing a method of interface is overriding or not in java

由 ╄→гoц情女王★ 提交于 2019-12-09 12:09:43
问题 I know this might be crazy but today one of my friend puzzled by asking when we implement an interface in java is it considered as method overriding. I told him it is not overriding as we are providing working(definition) of method first time when we implement any interface. To support multiple inheritance java provide interface but he was not convinced and was arguing. Please bring some light on to the topic. 回答1: The term "overriding" applies when there is an existing implementation of the

How is pointer to member function implemented in C++?

由 半城伤御伤魂 提交于 2019-12-09 10:50:07
问题 The pointer to member function in c++ is in three parts: Offset Address/index virtual? Offset is used for Pointer adjustment when derived object is called using base pointer. How is this offset implemented? Is it pointer to some table, one table for each derived class and the table contains entries of the form (base X, offset) ? Also, where can I get more info about this? 回答1: First you should note that a C++ method can be implemented (and is normally implemented) just as a regular function

Controlling read/write access to fields

由 百般思念 提交于 2019-12-09 07:42:28
Suppose that we would like to separate out the read and write access in an interface pattern as below. namespace accesspattern { namespace ReadOnly { public interface IA { double get_a(); } } namespace Writable { public interface IA : ReadOnly.IA { void set_a(double value); } } } This is easy to implement: namespace accesspattern { namespace ReadOnly { public class A : IA { protected double a; public double get_a() { return a; } } } namespace Writable { public class A : ReadOnly.A, IA { public void set_a(double value) { base.a = value; } } } } Suppose that we need another class which inherits

If one class is derived from another that is derived from Object, is that “multiple inheritence”

由 醉酒当歌 提交于 2019-12-09 03:58:30
问题 The fact about Java is that it does not support the multiple inheritance. But I have a question that the base class of all java classes is Object. Now we have two classes : Class A and Class B. B is inherited from A then the Base class of B would be the Object and A , so here, the multiple inheritance took place. Anyone will please help me to clear my doubt? 回答1: The concept of Multiple Inheritance means, that you can have a class A, B and C where A is derived from B and C like this: class A

more c++ multiple inheritance fun [duplicate]

由 家住魔仙堡 提交于 2019-12-09 03:24:19
问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: C++ pointer multi-inheritance fun. (Follow up on: C++ pointer multi-inheritance fun ) I'm writing some code involving inheritance from a basic ref-counting pointer class; and some intricacies of C++ popped up. I've reduced it as follows: Suppose I have: class A{int x, y;}; class B{int xx, yy;}; class C: public A, public B {int z;}; C c; C* pc = &c; B* pb = &c; A* pa = &c; // does pa point to a valid A object? //
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