好奇地重复出现的模板-变化 [英] Curiously recurring template - variation

问题描述

关于 CRP ，如果我想对它进行一些改动(使用模板template参数)时出现编译错误:

Regarding CRP if I want to implement a slight variation of it (using template template parameter) I get a compile error:

template <template <typename T> class Derived>
class Base
{
public:
    void CallDerived()
    {
        Derived* pT = static_cast<Derived*> (this);
        pT->Action(); // instantiation invocation error here
    }
};

template<typename T>
class Derived: public Base<Derived>
{
public:
    void Action()
    {
    }
};

我不确定是否会选择这种形式(对我而言不是编译形式)而不是使用这种形式(这种方式有效)

I am not exactly sure one would chose this form (that does not compile for me) instead of using this though (this works)

template <typename Derived>
class Base
{
public:
    void CallDerived()
    {
        Derived* pT = static_cast<Derived*> (this);
        pT->Action();
    }
};

template<typename T>
class Derived: public Base<Derived<T>>
{
public:
    void Action()
    {
    }
};

推荐答案

这也应该编译.我们只需要获取其他明确指定的模板参数

This should compile as well. We just need to get the other template parameter specified explicitly

 template <typename T, template <typename T> class Derived>
 class Base
 {
 public:
     void CallDerived()
     {
        Derived<T>* pT = static_cast<Derived<T>*> (this);
        pT->Action(); // instantiation invocation error here
     }
 };

template<typename T>
class Derived: public Base<T,Derived>
{
public:
    void Action()
    {
    }
};

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