enum class MyErrorCondition {

kChenggong,

kWangluoCuowu,

kQingqiuCuowu,

kFuwuqiCuowu,

};

class MyErrorCategory: public std::error_category

{

public:

static MyErrorCategory const& instance() {

static MyErrorCategory instance;

return instance;

}

char const *name() const noexcept override {

return "MyErrorCategory";

}

std::string message(int code) const override {

return "Message";

}

bool equivalent(std::error_code const& code, int condition) const noexcept override {

auto const& yourErrorCodeCategory = std::error_code(YourErrorCode{}).category();

if (code.category() == yourErrorCodeCategory) {

switch (static_cast<MyErrorCondition>(condition)) {

case MyErrorCondition::kChenggong:

return code == YourErrorCode::kSuccess;

case MyErrorCondition::kWangluoCuowu:

return code == YourErrorCode::kNetworkError;

case MyErrorCondition::kQingqiuCuowu:

return code == YourErrorCode::kBadRequest;

case MyErrorCondition::kFuwuqiCuowu:

return code == YourErrorCode::kServerError;

}

}

return false;

}

};

// error_condition 同样需要特化模版启动重载

namespace std {

template<>

struct is_error_condition_enum<MyErrorCondition>: true_type {};

}

// error_condition 同样可以通过工厂函数构造

std::error_condition make_error_condition(MyErrorCondition code)

{

return {static_cast<int>(code), MyErrorCategory::instance()};

}

int main()

{

std::error_code code = YourErrorCode::kNetworkError;

std::error_condition condition = MyErrorCondition::kWangluoCuowu;

std::cout << (code == condition) << '\n';

}