一个用来ghs的、使用了concept、折叠表达式、模板形参包做基类列表等技巧的模板元编程Mixin Demo

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昨天看Mixin时突发奇想，写着玩的。图一乐。

直接上代码，受限于平台，Show()部分自行脑补。

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#include <concepts>
#include <iostream>

template<typename T>
concept IsSexuality = requires{ T::Show(); };

template<IsSexuality... Sexuality>
struct GirlFriend :private Sexuality...
{
	constexpr GirlFriend() :Sexuality()... {}
	constexpr void ShowSexuality() const
	{
		std::cout << "I have a girl friend.\n";
		if constexpr (sizeof...(Sexuality) > 0)
		{
			std::cout << "She can:\n";
			((Sexuality::Show()), ...);
		} else
		{ std::cout << "She was a virgin.\n"; }
	}
};
struct MakeLoveable
{ static void Show() { std::cout << "Make love with me.\n"; } };
struct BlowJobable
{ static void Show() { std::cout << "BlowJob.\n"; } };
struct FootJobable
{ static void Show() { std::cout << "FootJob.\n"; } };
//...

template<typename T>
concept IsSexSkill = IsSexuality<T> && !std::same_as<T, MakeLoveable>;

template<IsSexSkill... SexSkills>
using ReallyGirlFriend = GirlFriend<MakeLoveable, SexSkills...>;

int main()
{
	constexpr GirlFriend girlFriend;
	constexpr ReallyGirlFriend<> reallyGirlFriend;
	constexpr ReallyGirlFriend<BlowJobable, FootJobable> sexyGirlFriend;
	girlFriend.ShowSexuality();
	reallyGirlFriend.ShowSexuality();
	sexyGirlFriend.ShowSexuality();
}

//output:
/*------------------------
I have a girl friend.
She was a virgin.
I have a girl friend.
She can:
Make love with me.
I have a girl friend.
She can:
Make love with me.
BlowJob.
FootJob.
------------------------*/

原文链接: https://zhuanlan.zhihu.com/p/460970247