When you combine these two facts you are left with the problem that if you make a virtual method call in a constructor, and it is not the most derived type in its inheritance hierarchy, that it will be called on a class whose constructor has not been run, and therefore may not be in...
It is often seen, that a virtual call in the constructor is meant to allow the derived type to set up some aspect of the base type. Such virtual method, in fact, should be a pure function that returns some value and doesn't depend on the state of the derived type. If this is the...
{privatestringfoo;publicChild() { foo ="HELLO"; }protectedoverridevoidDoSomething() { Console.WriteLine(foo.ToLower()); } } 如果实例化Child会抛出NullReferenceException异常。 详情请参考:http://stackoverflow.com/questions/119506/virtual-member-call-in-a-constructor...
I want to call a virtual function that handles a member within a derivative class constructor, a destructor. Even if I pay attention to the initialization order (by initializing members after the virtual function call is complete), is there a possibility that an undefined action will occur becau...
There are different ways to approach this problem. One is to turn logTransaction into a non-virtual function in Transaction, then require that derived class constructors pass the necessary log information to the Transaction constructor. That function can then safely call the nonvirtual logTransaction...
Note:此处需要传入如下flag:-fno-elide-constructors 禁止RVO/NRVO 而针对d = func()语句的实现,则为 learax,[rbp-24]// 临时对象的地址movrdi,raxcallfunc()// 在func中进行构造leardx,[rbp-24]learax,[rbp-32]movrsi,rdxmovrdi,rax// 将上述临时对象拷贝到main中分配的空间中callDerived::Derived(Deri...
To call the constructor, we use constructor chaining. The basic purpose of using abstract classes is to maintain a uniform interface inside all derived classes. This means if there are two classes inheriting from an abstract class, both classes should provide the implementation of a pure virtual...
area@Shape@@UBENXZ)//std::cout << "creating shape, area = " << area() << std::endl;std::cout<<"creating shape, value = "<<value()<<std::endl;//indirectly call pure virtual function in constructor}public:virtualdoublearea()const=0;doublevalue()const{returnValuePerSquareUnit*area()...
If the class is final then you should be able to call the function in the constructor or destructor with result as you expect (as this would have the same behavior as calling a non-virtual function at this point). But I'm having a hard time imagining a non-contrived case where you'd...
functionPureComponent(props,context,updater){this.props=props;this.context=context;this.refs=emptyObject;this.updater=updater||ReactNoopUpdateQueue;}constpureComponentPrototype=(PureComponent.prototype=newComponentDummy());pureComponentPrototype.constructor=PureComponent;Object.assign(pureComponentPrototype,Component.pr...