Singleton example (C++11)

CurlSingletonExample.cpp

// Curl.hpp

#ifndef CURL_HPP
#define CURL_HPP

#include <iostream>
#include <curl/curl.h>

// This Singleton is NOT thread-safe (perdoname madre por mi vida loca)
class Curl {
private:
    static Curl * _instance;
protected:
    Curl();
    ~Curl();
public:
    // This is a Singleton: disable all kinds of copy/move
    Curl(const Curl&) = delete;
    Curl(Curl&&) = delete;
    Curl& operator=(const Curl&) = delete;
    Curl& operator=(Curl&&) = delete;

    static Curl *GetInstance();
    std::string get(const std::string& url);
};

#endif // CURL_HPP

// Curl.cpp
#include "Curl.hpp"

Curl* Curl::_instance = nullptr;

// "curl_global_init is not thread safe. You must not call it when any other
// thread in the program (i.e. a thread sharing the same memory) is running."
// (https://curl.se/libcurl/c/curl_global_init.html)

Curl::Curl() {
    CURLcode ret = curl_global_init(CURL_GLOBAL_DEFAULT);
    if (ret != CURLE_OK) {
        std::cout << "Curl init BAD:" << curl_easy_strerror(ret) << std::endl;
    } else {
        std::cout << "Curl init OK" << std::endl;
    }
}

Curl::~Curl() {
    curl_global_cleanup();
}

Curl * Curl::GetInstance() {
    if (_instance == nullptr) {
        _instance = new Curl();
    }
    return _instance;
}