example.cpp

#include "library.cpp"
#include <iostream>

int main() {

	std::cout << "Start of program" << std::endl;

	typedef int(*myfunc)(int);

	JLib::Library MyLibrary("xyz");
	myfunc MyFunctionExport = MyLibrary.GetExport<myfunc>("MyFunctionExport");


	while (true) {}

	return 0;
}

library.cpp

#include "library.hpp"

#ifdef _DEBUG
#include <iostream>
#endif

#ifdef _WIN32
wchar_t * JLib::_WINDOWS_wchar_t(const char* normal) {

	size_t insize = strlen(normal);
	size_t outSize;

	wchar_t *wcstr = new wchar_t[strlen(normal) + 1];
	mbstowcs_s(&outSize, wcstr, insize + 1, normal, insize);

	return wcstr;
}
#endif

JLib::Library::Library(std::string File) {

#ifdef _WIN32
	File += ".dll";
#elif defined __unix__
	File += ".so";
#elif defined __APPLE__
	File += ".dylib";
#endif

#ifdef _DEBUG
	std::cout << "Loading library " << File << std::endl;
#endif

#ifdef _WIN32
	wchar_t *wcstr = JLib::_WINDOWS_wchar_t(File.c_str());
	this->Module = JLIB_LIBRARY_OPEN(wcstr);
	delete[] wcstr;
#else
	this->Module = JLIB_LIBRARY_OPEN(File.c_str());
#endif

	if (this->Module == NULL) {

#ifdef _DEBUG
		std::cout << "Loading library " << File << " failed!" << std::endl;
#endif

		throw std::exception("Could not load library");
	}
}

JLib::library_export JLib::Library::GetExportRaw(std::string export_name) {

#ifdef _DEBUG
	std::cout << "Loading export symbol " << export_name << std::endl;
#endif

	if (this->Module != NULL) {

		JLib::library_export Export = JLIB_LIBRARY_REQS(this->Module, export_name.c_str());
		if (Export == NULL) {

#ifdef _DEBUG
			std::cout << "Loading export symbol " << export_name << " failed!" << std::endl;
#endif

			throw std::exception( "Could not load export" );
		}
		else {
			return Export;
		}

	}
	return (JLib::library_export)nullptr;
}

JLib::Library::~Library() {
	JLIB_LIBRARY_CLOSE(this->Module);
}

library.hpp

#pragma once

#ifdef _WIN32
#include <windows.h>
#define JLIB_LIBRARY_OPEN LoadLibrary
#define JLIB_LIBRARY_REQS(x,y) GetProcAddress(x, (LPSTR) y )
#define JLIB_LIBRARY_CLOSE FreeLibrary
#else
#include <dlfcn.h>
#define JLIB_LIBRARY_OPEN(x) dlopen(x, RTLD_LAZY)
#define JLIB_LIBRARY_REQS dlsym
#define JLIB_LIBRARY_CLOSE dlclose
#endif

#ifdef __APPLE__
#define JLIB_LIBRARY_OPEN(x) dlopen(x, RTLD_LAZY)
#endif

#include <string>
#include <exception>

namespace JLib {

#ifdef _WIN32
	typedef HMODULE library_handle;
	typedef FARPROC library_export;
#else
	typedef void* library_handle;
	typedef void* library_export;
#endif

#ifdef _WIN32
	wchar_t * _WINDOWS_wchar_t(const char* normal);
#endif

	class Library {
	public:
		Library(std::string File);
		library_export GetExportRaw(std::string export_name);

		template<typename functype>
		functype GetExport(std::string export_name) {
			return (functype)GetExportRaw(export_name);
		}

		~Library();

	private:
		library_handle Module;
	};



} // namespace JLib