c++使用宏检测类是否包含某个函数或者变量属性

忘是亡心i 2022-01-22 10:25 259阅读 0赞

对于特定的函数或者变量属性检测一个特定的参数类：

#include <iostream>
    #include <boost/smart_ptr.hpp>
    
    #include <type_traits>
    using namespace boost;
    using namespace std;
    
    #define _CAT(A, B) A##B
    #define STR(s) #s
    #define CAT(A,B) _CAT(A,B)
    #define CHECKER_PREFIX __has_member_function_
    #define HAS_MEMBER_FUNC_CHECKER_NAME(FUNC) CAT(CHECKER_PREFIX, FUNC)
    
    #define HAS_MEMBER_FUNC_CHECKER(FUNC) template <typename T> \
     struct HAS_MEMBER_FUNC_CHECKER_NAME(FUNC){ \
     template <typename C> static std::true_type test(decltype(&C::FUNC)); \
     template <typename C> static std::false_type test(...); \
     static constexpr bool value = std::is_same<decltype(test<T>(nullptr)),std::true_type>::value; \
    };
    
    #define HAS_MEMBER_FUNC(TYPE, FUNC) (HAS_MEMBER_FUNC_CHECKER_NAME(FUNC)<TYPE>::value)
    
    
    class TestA{
    public:
        int* foo(){
    
            int* a =new int(1);
            return a;
    
        }
    
        static int foo2(){
            return  1;
        }
    
        static const int foo3;
    };
    
    HAS_MEMBER_FUNC_CHECKER(foo);
    HAS_MEMBER_FUNC_CHECKER(foo2);
    HAS_MEMBER_FUNC_CHECKER(foo3);
    int main() {
    
        static_assert(HAS_MEMBER_FUNC(TestA, foo));
        std::cout<<HAS_MEMBER_FUNC(TestA, foo) <<std::endl;
    
        return 0;
    }

对于确定参数类型的泛型成员函数：

#include <iostream>
    #include <boost/smart_ptr.hpp>
    
    #include <type_traits>
    using namespace boost;
    using namespace std;
    
    #define _CAT(A, B) A##B
    #define STR(s) #s
    #define CAT(A,B) _CAT(A,B)
    // 对于固定个数的模版类，检测某一个属性或者函数是否存在
    #define CHECKER_PREFIX2 _has_member_fcuntoin2_
    #define HAS_MEMBER_FUNC_CHECK_NAME2_(FUNC) CAT(CHECKER_PREFIX2,FUNC)
    
    #define HAS_MEMBER_FUNC_CEHCKER2(FUNC) template<typename T, typename R> \
        struct HAS_MEMBER_FUNC_CHECK_NAME2_(FUNC){ \
        template<typename C> static std::true_type test(decltype(&C::template FUNC<R>)); \
        template<typename C> static std::false_type test(...); \
        static constexpr bool value = std::is_same<decltype(test<T>(nullptr)),std::true_type>::value; \
    }
    
    // #define IF_HAS_MEMBER_FUNC2(FUNC,CLASS_,CLASS_F_T) (HAS_MEMBER_FUNC_CEHCK_NAME2_(FUNC)<CLASS_ ,CLASS_F_T>::value)
    
    
    class TestA{
    public:
        int* foo(){
    
            int* a =new int(1);
            return a;
    
        }
    
        static int foo2(){
            return  1;
        }
    
        template <typename T>
        static  int foo4(){
            return 1;
        }
    
        static const int foo3;
    };
    
    
    //含有固定类型的模版类
    HAS_MEMBER_FUNC_CEHCKER2(foo4);
    
    int main() {
        std::cout<< HAS_MEMBER_FUNC_CHECK_NAME2_(foo4)<TestA,char>::value << std::endl; //输出 1
        std::cout<< HAS_MEMBER_FUNC_CHECK_NAME2_(foo4)<TestA,int>::value << std::endl; // 输出1
     
        return 0;
    }

参考：[https://harrychen.xyz/2019/06/04/cpp-17-mock-concept/?nsukey=gtNT%2F95OLtBrNsgLAsZOVMljsbaBpJ7REBnA1BvfikjM9tyPnENnFyjpsh%2BhRwlALgEl4BCk73Zz3o5nPVLCWQhoMlWgL8h1GPiQJ%2BS%2FrpVE6IBF8gG4s9La1WsVI%2BPGPmZoVO8iT54Lr%2Bc4H6dtqZYJ1Q7tZBtkeWTLdA%2Fe9bVIAgatgmL2ZDfocdgXQRBPRBvoJd2IgJpM9X1q51HKZQ%3D%3D&from=timeline&isappinstalled=0][https_harrychen.xyz_2019_06_04_cpp-17-mock-concept_nsukey_gtNT_2F95OLtBrNsgLAsZOVMljsbaBpJ7REBnA1BvfikjM9tyPnENnFyjpsh_2BhRwlALgEl4BCk73Zz3o5nPVLCWQhoMlWgL8h1GPiQJ_2BS_2FrpVE6IBF8gG4s9La1WsVI_2BPGPmZoVO8iT54Lr_2Bc4H6dtqZYJ1Q7tZBtkeWTLdA_2Fe9bVIAgatgmL2ZDfocdgXQRBPRBvoJd2IgJpM9X1q51HKZQ_3D_3D_from_timeline_isappinstalled_0]

[https_harrychen.xyz_2019_06_04_cpp-17-mock-concept_nsukey_gtNT_2F95OLtBrNsgLAsZOVMljsbaBpJ7REBnA1BvfikjM9tyPnENnFyjpsh_2BhRwlALgEl4BCk73Zz3o5nPVLCWQhoMlWgL8h1GPiQJ_2BS_2FrpVE6IBF8gG4s9La1WsVI_2BPGPmZoVO8iT54Lr_2Bc4H6dtqZYJ1Q7tZBtkeWTLdA_2Fe9bVIAgatgmL2ZDfocdgXQRBPRBvoJd2IgJpM9X1q51HKZQ_3D_3D_from_timeline_isappinstalled_0]: https://harrychen.xyz/2019/06/04/cpp-17-mock-concept/?nsukey=gtNT%2F95OLtBrNsgLAsZOVMljsbaBpJ7REBnA1BvfikjM9tyPnENnFyjpsh%2BhRwlALgEl4BCk73Zz3o5nPVLCWQhoMlWgL8h1GPiQJ%2BS%2FrpVE6IBF8gG4s9La1WsVI%2BPGPmZoVO8iT54Lr%2Bc4H6dtqZYJ1Q7tZBtkeWTLdA%2Fe9bVIAgatgmL2ZDfocdgXQRBPRBvoJd2IgJpM9X1q51HKZQ%3D%3D&from=timeline&isappinstalled=0