// More examples you can find in tests #include <asenum/asenum.h> #include <string> #include <chrono> #include <iostream> // ===== DECLARATION ===== enum class ErrorCode{Unknown, Success, Timeout }; // Associate enum 'ErrorCode' with AsEnum 'AnyError' using AnyError = asenum::AsEnum< asenum::Case11<ErrorCode, ErrorCode::Unknown, std::string>, asenum::Case11<ErrorCode, ErrorCode::Success, void>, asenum::Case11<ErrorCode, ErrorCode::Timeout, std::chrono::seconds> > // ===== USAGE ===== void LogError(const AnyError& error){error.doSwitch() .ifCase<ErrorCode::Unknown>([] (const std::string& value){std::cout << "Unknown error: " << value << "\n"}) .ifCase<ErrorCode::Success>([]{std::cout << "Success\n"}) .ifCase<ErrorCode::Timeout>([] (const std::chrono::seconds& value){std::cout << "Timed out after: " << value.count() << "\n"}) .ifDefault([]{std::cout << "Default\n"})} int main(){// ===== CREATION ===== LogError(AnyError::create<ErrorCode::Unknown>("test.api.com")); LogError(AnyError::create<ErrorCode::Success>()); LogError(AnyError::create<ErrorCode::Timeout>(std::chrono::seconds(1))); return 0} 

// ===== Mapping ====== std::string ErrorToString(const AnyError& error){// All cases covered const auto stringRepresentation = error.doMap<std::string>() .ifCase<ErrorCode::Unknown>([] (const std::string& value){return value}) .ifCase<ErrorCode::Success>([]{return "Success"}) .ifCase<ErrorCode::Timeout>([] (const std::chrono::seconds& value){return "Timed out after: " + std::to_string(value.count())}); return stringRepresentation} // ===== Partial Mapping ====== std::string ErrorToString2(const AnyError& error){// All cases covered const auto stringRepresentation = error.doMap<std::string>() .ifCase<ErrorCode::Success>([]{return "Success"}) .ifDefault([]{return "Unknown error"}); return stringRepresentation} 

void Equality(const AnyError& error1, const AnyError& error2){// We can check if error1 == error2 // Cases differ => NOT Equal // Cases same AND underlying values same => Equal const bool equal = error1 == error2} void Comparability(const AnyError& error1, const AnyError& error2){// We can check how error1 relates to error2 // Cases of error1 and error2 differ => Compare case ordering // Cases same => Compare underlying values const bool less = error1 < error2; const bool lessEqual = error1 <= error2; const bool greater = error1 > error2; const bool greaterEqual = error1 >= error2} 

#include <asenum/asenum.h> #include <string> #include <chrono> #include <iostream> #include <cmath> enum class RootsType{None, Single, Pair }; using Roots = asenum::AsEnum< asenum::Case11<RootsType, RootsType::None, void>, asenum::Case11<RootsType, RootsType::Single, double>, asenum::Case11<RootsType, RootsType::Pair, std::pair<double, double>> > Roots FindRoots(const double a, const double b, const double c){const double d = (b * b) - (4 * a * c); if (d < 0){return Roots::create<RootsType::None>()} const double x1 = (-b + sqrt(d)) / (2 * a); const double x2 = (-b - sqrt(d)) / (2 * a); return x1 == x2 ? Roots::create<RootsType::Single>(x1) : Roots::create<RootsType::Pair>(std::make_pair(x1, x2))} double ReadK(const std::string& name){double k = 0; std::cout << "Input " << name << ": "; std::cin >> k; return k} int main(){const double a = ReadK("a"); const double b = ReadK("b"); const double c = ReadK("c"); const Roots roots = FindRoots(a, b, c); roots.doSwitch() .ifCase<RootsType::None>([]{std::cout << "No roots\n"}) .ifCase<RootsType::Single>([] (const double x){std::cout << "Single (equal) roots: " << x}) .ifCase<RootsType::Pair>([] (const std::pair<double, double>& roots){std::cout << "Different roots. x1 = " << roots.first << "; x2 = " << roots.second << ".\n"}); return 0} 

#include <asenum/asenum.h> #include <string> #include <vector> enum class BarCodeType{UPC, QrCode }; using BarCode = asenum::AsEnum< asenum::Case11<BarCodeType, BarCodeType::UPC, std::vector<uint8_t>>, asenum::Case11<BarCodeType, BarCodeType::QrCode, std::vector<uint8_t>>> > std::string ConvertUPCToLink(const std::vector<uint8_t>& photo){std::string link; // perform some computations... return link} std::string ConvertQrCodeToLink(const std::vector<uint8_t>& photo){std::string link; // perform some computations... return link} std::string ConvertBarCodeToLink(const BarCode& barCode){return barCode.doMap<std::string>() .ifCase<BarCodeType::UPC>(ConvertUPCToLink) .ifCase<BarCodeType::QrCode>(ConvertQrCodeToLink)} 

enum class DownloadResultType{Data, Error, Canceled }; using DownloadResult = asenum::AsEnum< asenum::Case11<DownloadResultType, DownloadResultType::Data, std::string>, asenum::Case11<DownloadResultType, DownloadResultType::Error, int>, asenum::Case11<DownloadResultType, DownloadResultType::Canceled, void> > DownloadResult DownloadFileFromLink(const std::string& link){// perform HTTP(s) request // return response data on success, ... return DownloadResult::create<DownloadResultType::Data>("..."); // ... or return server error, ... return DownloadResult::create<DownloadResultType::Error>(404); // ... or inform caller that request has been canceled. return DownloadResult::create<DownloadResultType::Canceled>()} int main(){const DownloadResult result = DownloadFileFromLink("http://test.api.com/download/file1.txt"); result.doSwitch() .ifCase<DownloadResultType::Data>([] (const std::string& content){std::cout << "Downloaded file content: " << content << "\n"}) .ifCase<DownloadResultType::Error>([] (const int errorCode){std::cout << "Request did fail with error: " << errorCode << "\n"}) .ifCase<DownloadResultType::Canceled>([]{std::cout << "Request has been canceled by user\n"}); return 0}