ODR test

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(odr_test)

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

add_executable(odr_test main.cpp)

add_library(odrl SHARED lib.cpp)

target_include_directories(odr_test PUBLIC ${PROJECT_SOURCE_DIR})
target_include_directories(odrl PUBLIC ${PROJECT_SOURCE_DIR})

target_link_libraries(odr_test PUBLIC dl)

lib.cpp

#include <template.hpp>

bool func() {
    auto& fac = Factory<int>::get_instance();
    fac.add("100", 100);
    fac.show();
    return true;
}

bool b = func();

main.cpp

#include <iostream>
#include <template.hpp>
#include <dlfcn.h>

int main() {


    void* handle = dlopen("./libodrl.so", RTLD_NOW);

    if (handle == nullptr) {
        std::cerr << "dlopen failed" << std::endl;
        return -1;
    }

    auto& f = Factory<int>::get_instance();
    f.show();

    int k = 0;
    auto b = f.find("100", k);

    std::cout << "k = " << k << " b = " << b << std::endl;

    return 0;
}

template.hpp

#ifndef ODR_TEST_TEMPLATE_HPP
#define ODR_TEST_TEMPLATE_HPP

#include <iostream>
#include <map>
#include <string>

template <typename T>
class Factory {
public:
    std::map<std::string, T> m;

    static Factory<T>& get_instance();

    Factory<T>() = default;
    Factory<T>(const Factory<T>&) = delete;
    Factory<T>(Factory<T>&&) = delete;
    void operator=(const Factory<T>&) = delete;
    void operator=(Factory<T>&&) = delete;

    void add(const std::string& s, const T& t) {
        m.emplace(s, t);
    }

    bool find(const std::string& s, T& t) {
        auto iter = m.find(s);
        if (iter != m.end()) {
            t = iter->second;
            return true;
        }
        return false;
    }

    void show() {
        for (const auto& kv : m) {
            std::cout << kv.first << ' ' << kv.second << std::endl;
        }
    }
};

template <>
Factory<int>& Factory<int>::get_instance(){
    static Factory<int> fac;
    return fac;
};

#endif//ODR_TEST_TEMPLATE_HPP