std::function && dll

dll.cpp

// [ref] http://stackoverflow.com/questions/15249465/c-dynamically-load-arbitrary-function-from-dll-into-stdfunction

template <typename T>
struct TypeParser {};

template <typename Ret, typename... Args>
struct TypeParser<Ret(Args...)> {
    static std::function<Ret(Args...)> createFunction(const FARPROC lpfnGetProcessID) {
        return std::function<Ret(Args...)>(reinterpret_cast<Ret (__stdcall *)(Args...)>(lpfnGetProcessID));
    }
};

template <typename T>
std::function<T> loadDllFunc(const std::string& dllName, const std::string& funcName) {
    // Load DLL.
    HINSTANCE hGetProcIDDLL = LoadLibrary(dllName.c_str());

    // Check if DLL is loaded.
    if (hGetProcIDDLL == NULL) {
        std::cerr << "Could not load DLL \"" << dllName << "\"" << std::endl;
        exit(EXIT_FAILURE);
    }

    // Locate function in DLL.
    FARPROC lpfnGetProcessID = GetProcAddress(hGetProcIDDLL, funcName.c_str());

    // Check if function was located.
    if (!lpfnGetProcessID) {
        std::cerr << "Could not locate the function \"" << funcName << "\" in DLL\"" << dllName << "\"" << std::endl;
        exit(EXIT_FAILURE);
    }

    // Create function object from function pointer.
    return TypeParser<T>::createFunction(lpfnGetProcessID);
}

/* usage:
// test.cc (test.dll)
#include <iostream>

// Declare function prototypes with "extern C" to prevent name mangling.
// Declare functions using __declspec(dllexport) to signify the intent to export.
extern "C" {
    __declspec(dllexport) int __stdcall plusFive(int);
    __declspec(dllexport) void __stdcall printHello();
}

int plusFive(int value) {
    return value + 5;
}

void printHello() {
    std::cout << "Hello!" << std::endl;
}

// main.cc
int main() {
    auto func1 = loadDllFunc<int(int)>("test.dll", "plusFive");
    auto func2 = loadDllFunc<void()>("test.dll", "printHello");

    std::cout << "Result of func1: " << func1(1) << std::endl;
    func2();
}
*/

Nice one. Thanks!