c++中同时用virtual和template
今天面试，被问到了这个问题。所以特意写个博文总结下。
首先明确，静多态指编译器多态，一般通过模板的方式来实现，比如SFINAF机制。
动多态一般使用虚表机制来实现。
先看场景一：
//
// Created by blacksungrass on 2022/3/8.
//
#include <iostream>
using namespace std;
template <typename T>
struct B{
T b;
B():b(2){}
virtual void print(){
cout<<b<<endl;
}
};
template <typename T>
struct A:public B<T>{
T a;
A():a(1){}
void print() override{
cout<<a<<endl;
}
};
int main(){
auto p = new A<double>();
p->print();
return 0;
}
以上代码是可以正确运行的
再看场景二：
//
// Created by blacksungrass on 2022/3/8.
//
#include <iostream>
using namespace std;
struct B{
template<typename T>
virtual void print(){
cout<<"i am B"<<endl;
}
};
struct A:public B{
template<typename T>
virtual void print() override{
cout<<"i am A"<<endl;
}
};
int main(){
B* p = new A();
p->print<>();
return 0;
}这个编译的话就会报错：error C2898: “void B::print(void)”: 成员函数模板不能是虚拟的
现在知道了，会报错。但更深一层，这个报错，是语言规定嘛？还是现有的编译器不支持？还是原理上就无法支持？
参考：https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#t83-do-not-declare-a-member-function-template-virtual
可以看到cpp语言上应该是不支持这个操作的。理由是”如果支持的话，只有到链接时才能生成虚函数表。“。
You’ve made some dscent points there. I lpoked oon the net
ffor more information about thhe issue andd fond most individals willl go along with your viesws oon thhis weeb site.
auroravpn
Mature human ovaryDick of the funniesBlack vintage leatherBest strip club in richmond vaMauritan sexy feetPhotos husbands sucking
cockHow big should the pussy be at 16Ralph lauren hot triangle bikiniSex model india xnxx Naakstrand gayChanging rooms girls videos free nakedOklahoma gay personalsMature
adult womenWoman pumping iron nudeHard porn fotoFree extreme
hairyGirl eat girl orgasm video https://core.xxxkernel.com/ Fuck mumSperm
analysisSexy mature bodysuitsPictures of rainforests top and bottomHot naked french girlsEvs fetishXxx
tv lesbianFat chick gett fuckedMale sports models nudeAmish nude widow xnxx Amateur secret videosFree nude celeb tgpEating licking cum
pantiesEscort agencies that accept crdit cardsPee in mixed companyColumbus ohio bbw women bbw menCostume porn thumb picsEpicuren facialsLipstick fetish 2008 jelsoft enterprises
ltdFree black porn linksPiss bottlePussy lips creampiesAnal milking for husband flickrVt heath care ass100 best porn films ever