如何检查两种类型是否来自同一模板类

问题描述

我想检查两种类型是否相同，但是不管它们的模板参数如何.像这样:

I would like to check if two types are the same, but regardless of their template parameters. Something like this:

template<class T>
class A {};
class B {};

int main() {
    cout << std::is_same_template<A<int>, A<string>>::value << endl; // true
    cout << std::is_same_template<A<int>, B>::value << endl; // false
}

我知道 std :: is_same 用于检查两种类型是否完全匹配.

I am aware of std::is_same for checking if two types match exacty.

我需要这个的原因:我有一个可以使用任何类型调用的模板化方法，但是我想禁止使用 A 类型(已模板化)调用该方法，可能是通过使用 static_assert .不是 A 的模板，我相信可以使用 std :: is_same 轻松完成，但是现在，我遇到了问题...

A reason why I need this:I have a templated method that can be called with any type, but I would like to prohibit that is is called with type A (which is templated), possibly by using a static_assert. Were A not templated, I believe it could be done easily using std::is_same, but now, I have a problem...

我可以手动排除一些常见的T，使用A，我正在寻找一种针对所有T的方法:

I can manually exclude A for a few common Ts, using, I am looking for a way to do it for all T:

static_assert(!std::is_same<parameter_type, A<int>>::value, "Cannot use this function with type A<T>");
static_assert(!std::is_same<parameter_type, A<double>>::value, "Cannot use this function with type A<T>");
static_assert(!std::is_same<parameter_type, A<bool>>::value, "Cannot use this function with type A<T>");

推荐答案

好吧，

#include <iostream>

template<class T>
struct A {};
struct B {};

template <typename T>
struct should_reject { static constexpr bool value = false; };

template <typename T>
struct should_reject<A<T>> { static constexpr bool value = true; };

template <typename T>
void rejectA(T t)
{
    std::cout << should_reject<T>::value << std::endl;
}

int main() {
    rejectA(B());         // false
    rejectA(1);           // false
    rejectA(1.0);         // false
    rejectA(A<B>());      // true
    rejectA(A<int>());    // true
    rejectA(A<double>()); // true
}

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