如果模板包含虚函数是否安全? [英] Is it safe if a template contains virtual function?

问题描述

模板的早期绑定和虚函数的后期绑定.因此，如果模板包含虚函数是否安全?

Early binding for template and late binding for virtual function. Therefore, is it safe if a template contains virtual function?

template<typename T> 
class base {
public:
    T data;
    virtual void fn(T t){}
};

推荐答案

它是完全安全的.一旦实例化了类模板，它就变成了普通类，就像其他类一样.

It is completely safe. Once you instantiate the class template, it becomes normal class just like other classes.

template<typename T> 
class base {
public:
    T data;
    virtual void fn(T t){}
};


class derived : base<int> {
public:
    virtual void fn(int t){} //override
};

base<int> *pBase = new derived();
pBase->fn(10); //calls derived::fn()

我还要指出，虽然在类模板中允许使用虚函数，但在类中不允许使用虚函数模板(如下所示):

I would also like to point out that while it is allowed virtual function in a class template, it is not allowed virtual function template inside a class (as shown below):

class A
{
   template<typename T>
   virtual void f(); //error: virtual function template is not allowed
};

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