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 /*
     Copyright (c) 2016-2017 ZeroMQ community
     Copyright (c) 2009-2011 250bpm s.r.o.
     Copyright (c) 2011 Botond Ballo
     Copyright (c) 2007-2009 iMatix Corporation
 
     Permission is hereby granted, free of charge, to any person obtaining a copy
     of this software and associated documentation files (the "Software"), to
     deal in the Software without restriction, including without limitation the
     rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
     sell copies of the Software, and to permit persons to whom the Software is
     furnished to do so, subject to the following conditions:
 
     The above copyright notice and this permission notice shall be included in
     all copies or substantial portions of the Software.
 
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
     IN THE SOFTWARE.
 */
 
 #ifndef __ZMQ_HPP_INCLUDED__
 #define __ZMQ_HPP_INCLUDED__
 
 #ifdef _WIN32
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
 #endif
 
 // included here for _HAS_CXX* macros
 #include <zmq.h>
 
 #if defined(_MSVC_LANG)
 #define CPPZMQ_LANG _MSVC_LANG
 #else
 #define CPPZMQ_LANG __cplusplus
 #endif
 // overwrite if specific language macros indicate higher version
 #if defined(_HAS_CXX14) && _HAS_CXX14 && CPPZMQ_LANG < 201402L
 #undef CPPZMQ_LANG
 #define CPPZMQ_LANG 201402L
 #endif
 #if defined(_HAS_CXX17) && _HAS_CXX17 && CPPZMQ_LANG < 201703L
 #undef CPPZMQ_LANG
 #define CPPZMQ_LANG 201703L
 #endif
 
 // macros defined if has a specific standard or greater
 #if CPPZMQ_LANG >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1900)
 #define ZMQ_CPP11
 #endif
 #if CPPZMQ_LANG >= 201402L
 #define ZMQ_CPP14
 #endif
 #if CPPZMQ_LANG >= 201703L
 #define ZMQ_CPP17
 #endif
 
 #if defined(ZMQ_CPP14) && !defined(_MSC_VER)
 #define ZMQ_DEPRECATED(msg) [[deprecated(msg)]]
 #elif defined(_MSC_VER)
 #define ZMQ_DEPRECATED(msg) __declspec(deprecated(msg))
 #elif defined(__GNUC__)
 #define ZMQ_DEPRECATED(msg) __attribute__((deprecated(msg)))
 #else
 #define ZMQ_DEPRECATED(msg)
 #endif
 
 #if defined(ZMQ_CPP17)
 #define ZMQ_NODISCARD [[nodiscard]]
 #else
 #define ZMQ_NODISCARD
 #endif
 
 #if defined(ZMQ_CPP11)
 #define ZMQ_NOTHROW noexcept
 #define ZMQ_EXPLICIT explicit
 #define ZMQ_OVERRIDE override
 #define ZMQ_NULLPTR nullptr
 #define ZMQ_CONSTEXPR_FN constexpr
 #define ZMQ_CONSTEXPR_VAR constexpr
 #define ZMQ_CPP11_DEPRECATED(msg) ZMQ_DEPRECATED(msg)
 #else
 #define ZMQ_NOTHROW throw()
 #define ZMQ_EXPLICIT
 #define ZMQ_OVERRIDE
 #define ZMQ_NULLPTR 0
 #define ZMQ_CONSTEXPR_FN
 #define ZMQ_CONSTEXPR_VAR const
 #define ZMQ_CPP11_DEPRECATED(msg)
 #endif
 #if defined(ZMQ_CPP14) && (!defined(_MSC_VER) || _MSC_VER > 1900) && (!defined(__GNUC__) || __GNUC__ > 5 || (__GNUC__ == 5 && __GNUC_MINOR__ > 3))
 #define ZMQ_EXTENDED_CONSTEXPR
 #endif
 #if defined(ZMQ_CPP17)
 #define ZMQ_INLINE_VAR inline
 #define ZMQ_CONSTEXPR_IF constexpr
 #else
 #define ZMQ_INLINE_VAR
 #define ZMQ_CONSTEXPR_IF
 #endif
 
 #include <cassert>
 #include <cstring>
 
 #include <algorithm>
 #include <exception>
 #include <iomanip>
 #include <sstream>
 #include <string>
 #include <vector>
 #ifdef ZMQ_CPP11
 #include <array>
 #include <chrono>
 #include <tuple>
 #include <memory>
 #endif
 
 #if defined(__has_include) && defined(ZMQ_CPP17)
 #define CPPZMQ_HAS_INCLUDE_CPP17(X) __has_include(X)
 #else
 #define CPPZMQ_HAS_INCLUDE_CPP17(X) 0
 #endif
 
 #if CPPZMQ_HAS_INCLUDE_CPP17(<optional>) && !defined(CPPZMQ_HAS_OPTIONAL)
 #define CPPZMQ_HAS_OPTIONAL 1
 #endif
 #ifndef CPPZMQ_HAS_OPTIONAL
 #define CPPZMQ_HAS_OPTIONAL 0
 #elif CPPZMQ_HAS_OPTIONAL
 #include <optional>
 #endif
 
 #if CPPZMQ_HAS_INCLUDE_CPP17(<string_view>) && !defined(CPPZMQ_HAS_STRING_VIEW)
 #define CPPZMQ_HAS_STRING_VIEW 1
 #endif
 #ifndef CPPZMQ_HAS_STRING_VIEW
 #define CPPZMQ_HAS_STRING_VIEW 0
 #elif CPPZMQ_HAS_STRING_VIEW
 #include <string_view>
 #endif
 
 /*  Version macros for compile-time API version detection                     */
 #define CPPZMQ_VERSION_MAJOR 4
 #define CPPZMQ_VERSION_MINOR 9
 #define CPPZMQ_VERSION_PATCH 0
 
 #define CPPZMQ_VERSION                                                              \
     ZMQ_MAKE_VERSION(CPPZMQ_VERSION_MAJOR, CPPZMQ_VERSION_MINOR,                    \
                      CPPZMQ_VERSION_PATCH)
 
 //  Detect whether the compiler supports C++11 rvalue references.
 #if (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 2))   \
      && defined(__GXX_EXPERIMENTAL_CXX0X__))
 #define ZMQ_HAS_RVALUE_REFS
 #define ZMQ_DELETED_FUNCTION = delete
 #elif defined(__clang__)
 #if __has_feature(cxx_rvalue_references)
 #define ZMQ_HAS_RVALUE_REFS
 #endif
 
 #if __has_feature(cxx_deleted_functions)
 #define ZMQ_DELETED_FUNCTION = delete
 #else
 #define ZMQ_DELETED_FUNCTION
 #endif
 #elif defined(_MSC_VER) && (_MSC_VER >= 1900)
 #define ZMQ_HAS_RVALUE_REFS
 #define ZMQ_DELETED_FUNCTION = delete
 #elif defined(_MSC_VER) && (_MSC_VER >= 1600)
 #define ZMQ_HAS_RVALUE_REFS
 #define ZMQ_DELETED_FUNCTION
 #else
 #define ZMQ_DELETED_FUNCTION
 #endif
 
 #if defined(ZMQ_CPP11) && !defined(__llvm__) && !defined(__INTEL_COMPILER)          \
   && defined(__GNUC__) && __GNUC__ < 5
 #define ZMQ_CPP11_PARTIAL
 #elif defined(__GLIBCXX__) && __GLIBCXX__ < 20160805
 //the date here is the last date of gcc 4.9.4, which
 // effectively means libstdc++ from gcc 5.5 and higher won't trigger this branch
 #define ZMQ_CPP11_PARTIAL
 #endif
 
 #ifdef ZMQ_CPP11
 #ifdef ZMQ_CPP11_PARTIAL
 #define ZMQ_IS_TRIVIALLY_COPYABLE(T) __has_trivial_copy(T)
 #else
 #include <type_traits>
 #define ZMQ_IS_TRIVIALLY_COPYABLE(T) std::is_trivially_copyable<T>::value
 #endif
 #endif
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(3, 3, 0)
 #define ZMQ_NEW_MONITOR_EVENT_LAYOUT
 #endif
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 1, 0)
 #define ZMQ_HAS_PROXY_STEERABLE
 /*  Socket event data  */
 typedef struct
 {
     uint16_t event; // id of the event as bitfield
     int32_t value;  // value is either error code, fd or reconnect interval
 } zmq_event_t;
 #endif
 
 // Avoid using deprecated message receive function when possible
 #if ZMQ_VERSION < ZMQ_MAKE_VERSION(3, 2, 0)
 #define zmq_msg_recv(msg, socket, flags) zmq_recvmsg(socket, msg, flags)
 #endif
 
 
 // In order to prevent unused variable warnings when building in non-debug
 // mode use this macro to make assertions.
 #ifndef NDEBUG
 #define ZMQ_ASSERT(expression) assert(expression)
 #else
 #define ZMQ_ASSERT(expression) (void) (expression)
 #endif
 
 namespace zmq
 {
 #ifdef ZMQ_CPP11
 namespace detail
 {
 namespace ranges
 {
 using std::begin;
 using std::end;
 template<class T> auto begin(T &&r) -> decltype(begin(std::forward<T>(r)))
 {
     return begin(std::forward<T>(r));
 }
 template<class T> auto end(T &&r) -> decltype(end(std::forward<T>(r)))
 {
     return end(std::forward<T>(r));
 }
 } // namespace ranges
 
 template<class T> using void_t = void;
 
 template<class Iter>
 using iter_value_t = typename std::iterator_traits<Iter>::value_type;
 
 template<class Range>
 using range_iter_t = decltype(
   ranges::begin(std::declval<typename std::remove_reference<Range>::type &>()));
 
 template<class Range> using range_value_t = iter_value_t<range_iter_t<Range>>;
 
 template<class T, class = void> struct is_range : std::false_type
 {
 };
 
 template<class T>
 struct is_range<
   T,
   void_t<decltype(
     ranges::begin(std::declval<typename std::remove_reference<T>::type &>())
     == ranges::end(std::declval<typename std::remove_reference<T>::type &>()))>>
     : std::true_type
 {
 };
 
 } // namespace detail
 #endif
 
 typedef zmq_free_fn free_fn;
 typedef zmq_pollitem_t pollitem_t;
 
 // duplicate definition from libzmq 4.3.3
 #if defined _WIN32
 #if defined _WIN64
 typedef unsigned __int64 fd_t;
 #else
 typedef unsigned int fd_t;
 #endif
 #else
 typedef int fd_t;
 #endif
 
 class error_t : public std::exception
 {
   public:
     error_t() ZMQ_NOTHROW : errnum(zmq_errno()) {}
     explicit error_t(int err) ZMQ_NOTHROW : errnum(err) {}
     virtual const char *what() const ZMQ_NOTHROW ZMQ_OVERRIDE
     {
         return zmq_strerror(errnum);
     }
     int num() const ZMQ_NOTHROW { return errnum; }
 
   private:
     int errnum;
 };
 
 namespace detail {
 inline int poll(zmq_pollitem_t *items_, size_t nitems_, long timeout_)
 {
     int rc = zmq_poll(items_, static_cast<int>(nitems_), timeout_);
     if (rc < 0)
         throw error_t();
     return rc;
 }
 }
 
 #ifdef ZMQ_CPP11
 ZMQ_DEPRECATED("from 4.8.0, use poll taking std::chrono::duration instead of long")
 inline int poll(zmq_pollitem_t *items_, size_t nitems_, long timeout_)
 #else
 inline int poll(zmq_pollitem_t *items_, size_t nitems_, long timeout_ = -1)
 #endif
 {
     return detail::poll(items_, nitems_, timeout_);
 }
 
 ZMQ_DEPRECATED("from 4.3.1, use poll taking non-const items")
 inline int poll(zmq_pollitem_t const *items_, size_t nitems_, long timeout_ = -1)
 {
     return detail::poll(const_cast<zmq_pollitem_t *>(items_), nitems_, timeout_);
 }
 
 #ifdef ZMQ_CPP11
 ZMQ_DEPRECATED("from 4.3.1, use poll taking non-const items")
 inline int
 poll(zmq_pollitem_t const *items, size_t nitems, std::chrono::milliseconds timeout)
 {
     return detail::poll(const_cast<zmq_pollitem_t *>(items), nitems,
                 static_cast<long>(timeout.count()));
 }
 
 ZMQ_DEPRECATED("from 4.3.1, use poll taking non-const items")
 inline int poll(std::vector<zmq_pollitem_t> const &items,
                 std::chrono::milliseconds timeout)
 {
     return detail::poll(const_cast<zmq_pollitem_t *>(items.data()), items.size(),
                 static_cast<long>(timeout.count()));
 }
 
 ZMQ_DEPRECATED("from 4.3.1, use poll taking non-const items")
 inline int poll(std::vector<zmq_pollitem_t> const &items, long timeout_ = -1)
 {
     return detail::poll(const_cast<zmq_pollitem_t *>(items.data()), items.size(), timeout_);
 }
 
 inline int
 poll(zmq_pollitem_t *items, size_t nitems, std::chrono::milliseconds timeout = std::chrono::milliseconds{-1})
 {
     return detail::poll(items, nitems, static_cast<long>(timeout.count()));
 }
 
 inline int poll(std::vector<zmq_pollitem_t> &items,
                 std::chrono::milliseconds timeout = std::chrono::milliseconds{-1})
 {
     return detail::poll(items.data(), items.size(), static_cast<long>(timeout.count()));
 }
 
 ZMQ_DEPRECATED("from 4.3.1, use poll taking std::chrono::duration instead of long")
 inline int poll(std::vector<zmq_pollitem_t> &items, long timeout_)
 {
     return detail::poll(items.data(), items.size(), timeout_);
 }
 
 template<std::size_t SIZE>
 inline int poll(std::array<zmq_pollitem_t, SIZE> &items,
                 std::chrono::milliseconds timeout = std::chrono::milliseconds{-1})
 {
     return detail::poll(items.data(), items.size(), static_cast<long>(timeout.count()));
 }
 #endif
 
 
 inline void version(int *major_, int *minor_, int *patch_)
 {
     zmq_version(major_, minor_, patch_);
 }
 
 #ifdef ZMQ_CPP11
 inline std::tuple<int, int, int> version()
 {
     std::tuple<int, int, int> v;
     zmq_version(&std::get<0>(v), &std::get<1>(v), &std::get<2>(v));
     return v;
 }
 
 #if !defined(ZMQ_CPP11_PARTIAL)
 namespace detail
 {
 template<class T> struct is_char_type
 {
     // true if character type for string literals in C++11
     static constexpr bool value =
       std::is_same<T, char>::value || std::is_same<T, wchar_t>::value
       || std::is_same<T, char16_t>::value || std::is_same<T, char32_t>::value;
 };
 }
 #endif
 
 #endif
 
 class message_t
 {
   public:
     message_t() ZMQ_NOTHROW
     {
         int rc = zmq_msg_init(&msg);
         ZMQ_ASSERT(rc == 0);
     }
 
     explicit message_t(size_t size_)
     {
         int rc = zmq_msg_init_size(&msg, size_);
         if (rc != 0)
             throw error_t();
     }
 
     template<class ForwardIter> message_t(ForwardIter first, ForwardIter last)
     {
         typedef typename std::iterator_traits<ForwardIter>::value_type value_t;
 
         assert(std::distance(first, last) >= 0);
         size_t const size_ =
           static_cast<size_t>(std::distance(first, last)) * sizeof(value_t);
         int const rc = zmq_msg_init_size(&msg, size_);
         if (rc != 0)
             throw error_t();
         std::copy(first, last, data<value_t>());
     }
 
     message_t(const void *data_, size_t size_)
     {
         int rc = zmq_msg_init_size(&msg, size_);
         if (rc != 0)
             throw error_t();
         if (size_) {
             // this constructor allows (nullptr, 0),
             // memcpy with a null pointer is UB
             memcpy(data(), data_, size_);
         }
     }
 
     message_t(void *data_, size_t size_, free_fn *ffn_, void *hint_ = ZMQ_NULLPTR)
     {
         int rc = zmq_msg_init_data(&msg, data_, size_, ffn_, hint_);
         if (rc != 0)
             throw error_t();
     }
 
     // overload set of string-like types and generic containers
 #if defined(ZMQ_CPP11) && !defined(ZMQ_CPP11_PARTIAL)
     // NOTE this constructor will include the null terminator
     // when called with a string literal.
     // An overload taking const char* can not be added because
     // it would be preferred over this function and break compatiblity.
     template<
       class Char,
       size_t N,
       typename = typename std::enable_if<detail::is_char_type<Char>::value>::type>
     ZMQ_DEPRECATED("from 4.7.0, use constructors taking iterators, (pointer, size) "
                    "or strings instead")
     explicit message_t(const Char (&data)[N]) :
         message_t(detail::ranges::begin(data), detail::ranges::end(data))
     {
     }
 
     template<class Range,
              typename = typename std::enable_if<
                detail::is_range<Range>::value
                && ZMQ_IS_TRIVIALLY_COPYABLE(detail::range_value_t<Range>)
                && !detail::is_char_type<detail::range_value_t<Range>>::value
                && !std::is_same<Range, message_t>::value>::type>
     explicit message_t(const Range &rng) :
         message_t(detail::ranges::begin(rng), detail::ranges::end(rng))
     {
     }
 
     explicit message_t(const std::string &str) : message_t(str.data(), str.size()) {}
 
 #if CPPZMQ_HAS_STRING_VIEW
     explicit message_t(std::string_view str) : message_t(str.data(), str.size()) {}
 #endif
 
 #endif
 
 #ifdef ZMQ_HAS_RVALUE_REFS
     message_t(message_t &&rhs) ZMQ_NOTHROW : msg(rhs.msg)
     {
         int rc = zmq_msg_init(&rhs.msg);
         ZMQ_ASSERT(rc == 0);
     }
 
     message_t &operator=(message_t &&rhs) ZMQ_NOTHROW
     {
         std::swap(msg, rhs.msg);
         return *this;
     }
 #endif
 
     ~message_t() ZMQ_NOTHROW
     {
         int rc = zmq_msg_close(&msg);
         ZMQ_ASSERT(rc == 0);
     }
 
     void rebuild()
     {
         int rc = zmq_msg_close(&msg);
         if (rc != 0)
             throw error_t();
         rc = zmq_msg_init(&msg);
         ZMQ_ASSERT(rc == 0);
     }
 
     void rebuild(size_t size_)
     {
         int rc = zmq_msg_close(&msg);
         if (rc != 0)
             throw error_t();
         rc = zmq_msg_init_size(&msg, size_);
         if (rc != 0)
             throw error_t();
     }
 
     void rebuild(const void *data_, size_t size_)
     {
         int rc = zmq_msg_close(&msg);
         if (rc != 0)
             throw error_t();
         rc = zmq_msg_init_size(&msg, size_);
         if (rc != 0)
             throw error_t();
         memcpy(data(), data_, size_);
     }
 
     void rebuild(void *data_, size_t size_, free_fn *ffn_, void *hint_ = ZMQ_NULLPTR)
     {
         int rc = zmq_msg_close(&msg);
         if (rc != 0)
             throw error_t();
         rc = zmq_msg_init_data(&msg, data_, size_, ffn_, hint_);
         if (rc != 0)
             throw error_t();
     }
 
     ZMQ_DEPRECATED("from 4.3.1, use move taking non-const reference instead")
     void move(message_t const *msg_)
     {
         int rc = zmq_msg_move(&msg, const_cast<zmq_msg_t *>(msg_->handle()));
         if (rc != 0)
             throw error_t();
     }
 
     void move(message_t &msg_)
     {
         int rc = zmq_msg_move(&msg, msg_.handle());
         if (rc != 0)
             throw error_t();
     }
 
     ZMQ_DEPRECATED("from 4.3.1, use copy taking non-const reference instead")
     void copy(message_t const *msg_)
     {
         int rc = zmq_msg_copy(&msg, const_cast<zmq_msg_t *>(msg_->handle()));
         if (rc != 0)
             throw error_t();
     }
 
     void copy(message_t &msg_)
     {
         int rc = zmq_msg_copy(&msg, msg_.handle());
         if (rc != 0)
             throw error_t();
     }
 
     bool more() const ZMQ_NOTHROW
     {
         int rc = zmq_msg_more(const_cast<zmq_msg_t *>(&msg));
         return rc != 0;
     }
 
     void *data() ZMQ_NOTHROW { return zmq_msg_data(&msg); }
 
     const void *data() const ZMQ_NOTHROW
     {
         return zmq_msg_data(const_cast<zmq_msg_t *>(&msg));
     }
 
     size_t size() const ZMQ_NOTHROW
     {
         return zmq_msg_size(const_cast<zmq_msg_t *>(&msg));
     }
 
     ZMQ_NODISCARD bool empty() const ZMQ_NOTHROW { return size() == 0u; }
 
     template<typename T> T *data() ZMQ_NOTHROW { return static_cast<T *>(data()); }
 
     template<typename T> T const *data() const ZMQ_NOTHROW
     {
         return static_cast<T const *>(data());
     }
 
     ZMQ_DEPRECATED("from 4.3.0, use operator== instead")
     bool equal(const message_t *other) const ZMQ_NOTHROW { return *this == *other; }
 
     bool operator==(const message_t &other) const ZMQ_NOTHROW
     {
         const size_t my_size = size();
         return my_size == other.size() && 0 == memcmp(data(), other.data(), my_size);
     }
 
     bool operator!=(const message_t &other) const ZMQ_NOTHROW
     {
         return !(*this == other);
     }
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(3, 2, 0)
     int get(int property_)
     {
         int value = zmq_msg_get(&msg, property_);
         if (value == -1)
             throw error_t();
         return value;
     }
 #endif
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 1, 0)
     const char *gets(const char *property_)
     {
         const char *value = zmq_msg_gets(&msg, property_);
         if (value == ZMQ_NULLPTR)
             throw error_t();
         return value;
     }
 #endif
 
 #if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
     uint32_t routing_id() const
     {
         return zmq_msg_routing_id(const_cast<zmq_msg_t *>(&msg));
     }
 
     void set_routing_id(uint32_t routing_id)
     {
         int rc = zmq_msg_set_routing_id(&msg, routing_id);
         if (rc != 0)
             throw error_t();
     }
 
     const char *group() const
     {
         return zmq_msg_group(const_cast<zmq_msg_t *>(&msg));
     }
 
     void set_group(const char *group)
     {
         int rc = zmq_msg_set_group(&msg, group);
         if (rc != 0)
             throw error_t();
     }
 #endif
 
     // interpret message content as a string
     std::string to_string() const
     {
         return std::string(static_cast<const char *>(data()), size());
     }
 #if CPPZMQ_HAS_STRING_VIEW
     // interpret message content as a string
     std::string_view to_string_view() const noexcept
     {
         return std::string_view(static_cast<const char *>(data()), size());
     }
 #endif
 
     /** Dump content to string for debugging.
     *   Ascii chars are readable, the rest is printed as hex.
     *   Probably ridiculously slow.
     *   Use to_string() or to_string_view() for
     *   interpreting the message as a string.
     */
     std::string str() const
     {
         // Partly mutuated from the same method in zmq::multipart_t
         std::stringstream os;
 
         const unsigned char *msg_data = this->data<unsigned char>();
         unsigned char byte;
         size_t size = this->size();
         int is_ascii[2] = {0, 0};
 
         os << "zmq::message_t [size " << std::dec << std::setw(3)
            << std::setfill('0') << size << "] (";
         // Totally arbitrary
         if (size >= 1000) {
             os << "... too big to print)";
         } else {
             while (size--) {
                 byte = *msg_data++;
 
                 is_ascii[1] = (byte >= 32 && byte < 127);
                 if (is_ascii[1] != is_ascii[0])
                     os << " "; // Separate text/non text
 
                 if (is_ascii[1]) {
                     os << byte;
                 } else {
                     os << std::hex << std::uppercase << std::setw(2)
                        << std::setfill('0') << static_cast<short>(byte);
                 }
                 is_ascii[0] = is_ascii[1];
             }
             os << ")";
         }
         return os.str();
     }
 
     void swap(message_t &other) ZMQ_NOTHROW
     {
         // this assumes zmq::msg_t from libzmq is trivially relocatable
         std::swap(msg, other.msg);
     }
 
     ZMQ_NODISCARD zmq_msg_t *handle() ZMQ_NOTHROW { return &msg; }
     ZMQ_NODISCARD const zmq_msg_t *handle() const ZMQ_NOTHROW { return &msg; }
 
   private:
     //  The underlying message
     zmq_msg_t msg;
 
     //  Disable implicit message copying, so that users won't use shared
     //  messages (less efficient) without being aware of the fact.
     message_t(const message_t &) ZMQ_DELETED_FUNCTION;
     void operator=(const message_t &) ZMQ_DELETED_FUNCTION;
 };
 
 inline void swap(message_t &a, message_t &b) ZMQ_NOTHROW
 {
     a.swap(b);
 }
 
 #ifdef ZMQ_CPP11
 enum class ctxopt
 {
 #ifdef ZMQ_BLOCKY
     blocky = ZMQ_BLOCKY,
 #endif
 #ifdef ZMQ_IO_THREADS
     io_threads = ZMQ_IO_THREADS,
 #endif
 #ifdef ZMQ_THREAD_SCHED_POLICY
     thread_sched_policy = ZMQ_THREAD_SCHED_POLICY,
 #endif
 #ifdef ZMQ_THREAD_PRIORITY
     thread_priority = ZMQ_THREAD_PRIORITY,
 #endif
 #ifdef ZMQ_THREAD_AFFINITY_CPU_ADD
     thread_affinity_cpu_add = ZMQ_THREAD_AFFINITY_CPU_ADD,
 #endif
 #ifdef ZMQ_THREAD_AFFINITY_CPU_REMOVE
     thread_affinity_cpu_remove = ZMQ_THREAD_AFFINITY_CPU_REMOVE,
 #endif
 #ifdef ZMQ_THREAD_NAME_PREFIX
     thread_name_prefix = ZMQ_THREAD_NAME_PREFIX,
 #endif
 #ifdef ZMQ_MAX_MSGSZ
     max_msgsz = ZMQ_MAX_MSGSZ,
 #endif
 #ifdef ZMQ_ZERO_COPY_RECV
     zero_copy_recv = ZMQ_ZERO_COPY_RECV,
 #endif
 #ifdef ZMQ_MAX_SOCKETS
     max_sockets = ZMQ_MAX_SOCKETS,
 #endif
 #ifdef ZMQ_SOCKET_LIMIT
     socket_limit = ZMQ_SOCKET_LIMIT,
 #endif
 #ifdef ZMQ_IPV6
     ipv6 = ZMQ_IPV6,
 #endif
 #ifdef ZMQ_MSG_T_SIZE
     msg_t_size = ZMQ_MSG_T_SIZE
 #endif
 };
 #endif
 
 class context_t
 {
   public:
     context_t()
     {
         ptr = zmq_ctx_new();
         if (ptr == ZMQ_NULLPTR)
             throw error_t();
     }
 
 
     explicit context_t(int io_threads_, int max_sockets_ = ZMQ_MAX_SOCKETS_DFLT)
     {
         ptr = zmq_ctx_new();
         if (ptr == ZMQ_NULLPTR)
             throw error_t();
 
         int rc = zmq_ctx_set(ptr, ZMQ_IO_THREADS, io_threads_);
         ZMQ_ASSERT(rc == 0);
 
         rc = zmq_ctx_set(ptr, ZMQ_MAX_SOCKETS, max_sockets_);
         ZMQ_ASSERT(rc == 0);
     }
 
 #ifdef ZMQ_HAS_RVALUE_REFS
     context_t(context_t &&rhs) ZMQ_NOTHROW : ptr(rhs.ptr) { rhs.ptr = ZMQ_NULLPTR; }
     context_t &operator=(context_t &&rhs) ZMQ_NOTHROW
     {
         close();
         std::swap(ptr, rhs.ptr);
         return *this;
     }
 #endif
 
     ~context_t() ZMQ_NOTHROW { close(); }
 
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use set taking zmq::ctxopt instead")
     int setctxopt(int option_, int optval_)
     {
         int rc = zmq_ctx_set(ptr, option_, optval_);
         ZMQ_ASSERT(rc == 0);
         return rc;
     }
 
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use get taking zmq::ctxopt instead")
     int getctxopt(int option_) { return zmq_ctx_get(ptr, option_); }
 
 #ifdef ZMQ_CPP11
     void set(ctxopt option, int optval)
     {
         int rc = zmq_ctx_set(ptr, static_cast<int>(option), optval);
         if (rc == -1)
             throw error_t();
     }
 
     ZMQ_NODISCARD int get(ctxopt option)
     {
         int rc = zmq_ctx_get(ptr, static_cast<int>(option));
         // some options have a default value of -1
         // which is unfortunate, and may result in errors
         // that don't make sense
         if (rc == -1)
             throw error_t();
         return rc;
     }
 #endif
 
     // Terminates context (see also shutdown()).
     void close() ZMQ_NOTHROW
     {
         if (ptr == ZMQ_NULLPTR)
             return;
 
         int rc;
         do {
             rc = zmq_ctx_term(ptr);
         } while (rc == -1 && errno == EINTR);
 
         ZMQ_ASSERT(rc == 0);
         ptr = ZMQ_NULLPTR;
     }
 
     // Shutdown context in preparation for termination (close()).
     // Causes all blocking socket operations and any further
     // socket operations to return with ETERM.
     void shutdown() ZMQ_NOTHROW
     {
         if (ptr == ZMQ_NULLPTR)
             return;
         int rc = zmq_ctx_shutdown(ptr);
         ZMQ_ASSERT(rc == 0);
     }
 
     //  Be careful with this, it's probably only useful for
     //  using the C api together with an existing C++ api.
     //  Normally you should never need to use this.
     ZMQ_EXPLICIT operator void *() ZMQ_NOTHROW { return ptr; }
 
     ZMQ_EXPLICIT operator void const *() const ZMQ_NOTHROW { return ptr; }
 
     ZMQ_NODISCARD void *handle() ZMQ_NOTHROW { return ptr; }
 
     ZMQ_DEPRECATED("from 4.7.0, use handle() != nullptr instead")
     operator bool() const ZMQ_NOTHROW { return ptr != ZMQ_NULLPTR; }
 
     void swap(context_t &other) ZMQ_NOTHROW { std::swap(ptr, other.ptr); }
 
   private:
     void *ptr;
 
     context_t(const context_t &) ZMQ_DELETED_FUNCTION;
     void operator=(const context_t &) ZMQ_DELETED_FUNCTION;
 };
 
 inline void swap(context_t &a, context_t &b) ZMQ_NOTHROW
 {
     a.swap(b);
 }
 
 #ifdef ZMQ_CPP11
 
 struct recv_buffer_size
 {
     size_t size;             // number of bytes written to buffer
     size_t untruncated_size; // untruncated message size in bytes
 
     ZMQ_NODISCARD bool truncated() const noexcept
     {
         return size != untruncated_size;
     }
 };
 
 #if CPPZMQ_HAS_OPTIONAL
 
 using send_result_t = std::optional<size_t>;
 using recv_result_t = std::optional<size_t>;
 using recv_buffer_result_t = std::optional<recv_buffer_size>;
 
 #else
 
 namespace detail
 {
 // A C++11 type emulating the most basic
 // operations of std::optional for trivial types
 template<class T> class trivial_optional
 {
   public:
     static_assert(std::is_trivial<T>::value, "T must be trivial");
     using value_type = T;
 
     trivial_optional() = default;
     trivial_optional(T value) noexcept : _value(value), _has_value(true) {}
 
     const T *operator->() const noexcept
     {
         assert(_has_value);
         return &_value;
     }
     T *operator->() noexcept
     {
         assert(_has_value);
         return &_value;
     }
 
     const T &operator*() const noexcept
     {
         assert(_has_value);
         return _value;
     }
     T &operator*() noexcept
     {
         assert(_has_value);
         return _value;
     }
 
     T &value()
     {
         if (!_has_value)
             throw std::exception();
         return _value;
     }
     const T &value() const
     {
         if (!_has_value)
             throw std::exception();
         return _value;
     }
 
     explicit operator bool() const noexcept { return _has_value; }
     bool has_value() const noexcept { return _has_value; }
 
   private:
     T _value{};
     bool _has_value{false};
 };
 } // namespace detail
 
 using send_result_t = detail::trivial_optional<size_t>;
 using recv_result_t = detail::trivial_optional<size_t>;
 using recv_buffer_result_t = detail::trivial_optional<recv_buffer_size>;
 
 #endif
 
 namespace detail
 {
 template<class T> constexpr T enum_bit_or(T a, T b) noexcept
 {
     static_assert(std::is_enum<T>::value, "must be enum");
     using U = typename std::underlying_type<T>::type;
     return static_cast<T>(static_cast<U>(a) | static_cast<U>(b));
 }
 template<class T> constexpr T enum_bit_and(T a, T b) noexcept
 {
     static_assert(std::is_enum<T>::value, "must be enum");
     using U = typename std::underlying_type<T>::type;
     return static_cast<T>(static_cast<U>(a) & static_cast<U>(b));
 }
 template<class T> constexpr T enum_bit_xor(T a, T b) noexcept
 {
     static_assert(std::is_enum<T>::value, "must be enum");
     using U = typename std::underlying_type<T>::type;
     return static_cast<T>(static_cast<U>(a) ^ static_cast<U>(b));
 }
 template<class T> constexpr T enum_bit_not(T a) noexcept
 {
     static_assert(std::is_enum<T>::value, "must be enum");
     using U = typename std::underlying_type<T>::type;
     return static_cast<T>(~static_cast<U>(a));
 }
 } // namespace detail
 
 // partially satisfies named requirement BitmaskType
 enum class send_flags : int
 {
     none = 0,
     dontwait = ZMQ_DONTWAIT,
     sndmore = ZMQ_SNDMORE
 };
 
 constexpr send_flags operator|(send_flags a, send_flags b) noexcept
 {
     return detail::enum_bit_or(a, b);
 }
 constexpr send_flags operator&(send_flags a, send_flags b) noexcept
 {
     return detail::enum_bit_and(a, b);
 }
 constexpr send_flags operator^(send_flags a, send_flags b) noexcept
 {
     return detail::enum_bit_xor(a, b);
 }
 constexpr send_flags operator~(send_flags a) noexcept
 {
     return detail::enum_bit_not(a);
 }
 
 // partially satisfies named requirement BitmaskType
 enum class recv_flags : int
 {
     none = 0,
     dontwait = ZMQ_DONTWAIT
 };
 
 constexpr recv_flags operator|(recv_flags a, recv_flags b) noexcept
 {
     return detail::enum_bit_or(a, b);
 }
 constexpr recv_flags operator&(recv_flags a, recv_flags b) noexcept
 {
     return detail::enum_bit_and(a, b);
 }
 constexpr recv_flags operator^(recv_flags a, recv_flags b) noexcept
 {
     return detail::enum_bit_xor(a, b);
 }
 constexpr recv_flags operator~(recv_flags a) noexcept
 {
     return detail::enum_bit_not(a);
 }
 
 
 // mutable_buffer, const_buffer and buffer are based on
 // the Networking TS specification, draft:
 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/n4771.pdf
 
 class mutable_buffer
 {
   public:
     constexpr mutable_buffer() noexcept : _data(nullptr), _size(0) {}
     constexpr mutable_buffer(void *p, size_t n) noexcept : _data(p), _size(n)
     {
 #ifdef ZMQ_EXTENDED_CONSTEXPR
         assert(p != nullptr || n == 0);
 #endif
     }
 
     constexpr void *data() const noexcept { return _data; }
     constexpr size_t size() const noexcept { return _size; }
     mutable_buffer &operator+=(size_t n) noexcept
     {
         // (std::min) is a workaround for when a min macro is defined
         const auto shift = (std::min)(n, _size);
         _data = static_cast<char *>(_data) + shift;
         _size -= shift;
         return *this;
     }
 
   private:
     void *_data;
     size_t _size;
 };
 
 inline mutable_buffer operator+(const mutable_buffer &mb, size_t n) noexcept
 {
     return mutable_buffer(static_cast<char *>(mb.data()) + (std::min)(n, mb.size()),
                           mb.size() - (std::min)(n, mb.size()));
 }
 inline mutable_buffer operator+(size_t n, const mutable_buffer &mb) noexcept
 {
     return mb + n;
 }
 
 class const_buffer
 {
   public:
     constexpr const_buffer() noexcept : _data(nullptr), _size(0) {}
     constexpr const_buffer(const void *p, size_t n) noexcept : _data(p), _size(n)
     {
 #ifdef ZMQ_EXTENDED_CONSTEXPR
         assert(p != nullptr || n == 0);
 #endif
     }
     constexpr const_buffer(const mutable_buffer &mb) noexcept :
         _data(mb.data()), _size(mb.size())
     {
     }
 
     constexpr const void *data() const noexcept { return _data; }
     constexpr size_t size() const noexcept { return _size; }
     const_buffer &operator+=(size_t n) noexcept
     {
         const auto shift = (std::min)(n, _size);
         _data = static_cast<const char *>(_data) + shift;
         _size -= shift;
         return *this;
     }
 
   private:
     const void *_data;
     size_t _size;
 };
 
 inline const_buffer operator+(const const_buffer &cb, size_t n) noexcept
 {
     return const_buffer(static_cast<const char *>(cb.data())
                           + (std::min)(n, cb.size()),
                         cb.size() - (std::min)(n, cb.size()));
 }
 inline const_buffer operator+(size_t n, const const_buffer &cb) noexcept
 {
     return cb + n;
 }
 
 // buffer creation
 
 constexpr mutable_buffer buffer(void *p, size_t n) noexcept
 {
     return mutable_buffer(p, n);
 }
 constexpr const_buffer buffer(const void *p, size_t n) noexcept
 {
     return const_buffer(p, n);
 }
 constexpr mutable_buffer buffer(const mutable_buffer &mb) noexcept
 {
     return mb;
 }
 inline mutable_buffer buffer(const mutable_buffer &mb, size_t n) noexcept
 {
     return mutable_buffer(mb.data(), (std::min)(mb.size(), n));
 }
 constexpr const_buffer buffer(const const_buffer &cb) noexcept
 {
     return cb;
 }
 inline const_buffer buffer(const const_buffer &cb, size_t n) noexcept
 {
     return const_buffer(cb.data(), (std::min)(cb.size(), n));
 }
 
 namespace detail
 {
 template<class T> struct is_buffer
 {
     static constexpr bool value =
       std::is_same<T, const_buffer>::value || std::is_same<T, mutable_buffer>::value;
 };
 
 template<class T> struct is_pod_like
 {
     // NOTE: The networking draft N4771 section 16.11 requires
     // T in the buffer functions below to be
     // trivially copyable OR standard layout.
     // Here we decide to be conservative and require both.
     static constexpr bool value =
       ZMQ_IS_TRIVIALLY_COPYABLE(T) && std::is_standard_layout<T>::value;
 };
 
 template<class C> constexpr auto seq_size(const C &c) noexcept -> decltype(c.size())
 {
     return c.size();
 }
 template<class T, size_t N>
 constexpr size_t seq_size(const T (&/*array*/)[N]) noexcept
 {
     return N;
 }
 
 template<class Seq>
 auto buffer_contiguous_sequence(Seq &&seq) noexcept
   -> decltype(buffer(std::addressof(*std::begin(seq)), size_t{}))
 {
     using T = typename std::remove_cv<
       typename std::remove_reference<decltype(*std::begin(seq))>::type>::type;
     static_assert(detail::is_pod_like<T>::value, "T must be POD");
 
     const auto size = seq_size(seq);
     return buffer(size != 0u ? std::addressof(*std::begin(seq)) : nullptr,
                   size * sizeof(T));
 }
 template<class Seq>
 auto buffer_contiguous_sequence(Seq &&seq, size_t n_bytes) noexcept
   -> decltype(buffer_contiguous_sequence(seq))
 {
     using T = typename std::remove_cv<
       typename std::remove_reference<decltype(*std::begin(seq))>::type>::type;
     static_assert(detail::is_pod_like<T>::value, "T must be POD");
 
     const auto size = seq_size(seq);
     return buffer(size != 0u ? std::addressof(*std::begin(seq)) : nullptr,
                   (std::min)(size * sizeof(T), n_bytes));
 }
 
 } // namespace detail
 
 // C array
 template<class T, size_t N> mutable_buffer buffer(T (&data)[N]) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, size_t N>
 mutable_buffer buffer(T (&data)[N], size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 template<class T, size_t N> const_buffer buffer(const T (&data)[N]) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, size_t N>
 const_buffer buffer(const T (&data)[N], size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 // std::array
 template<class T, size_t N> mutable_buffer buffer(std::array<T, N> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, size_t N>
 mutable_buffer buffer(std::array<T, N> &data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 template<class T, size_t N>
 const_buffer buffer(std::array<const T, N> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, size_t N>
 const_buffer buffer(std::array<const T, N> &data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 template<class T, size_t N>
 const_buffer buffer(const std::array<T, N> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, size_t N>
 const_buffer buffer(const std::array<T, N> &data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 // std::vector
 template<class T, class Allocator>
 mutable_buffer buffer(std::vector<T, Allocator> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, class Allocator>
 mutable_buffer buffer(std::vector<T, Allocator> &data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 template<class T, class Allocator>
 const_buffer buffer(const std::vector<T, Allocator> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, class Allocator>
 const_buffer buffer(const std::vector<T, Allocator> &data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 // std::basic_string
 template<class T, class Traits, class Allocator>
 mutable_buffer buffer(std::basic_string<T, Traits, Allocator> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, class Traits, class Allocator>
 mutable_buffer buffer(std::basic_string<T, Traits, Allocator> &data,
                       size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 template<class T, class Traits, class Allocator>
 const_buffer buffer(const std::basic_string<T, Traits, Allocator> &data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, class Traits, class Allocator>
 const_buffer buffer(const std::basic_string<T, Traits, Allocator> &data,
                     size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 
 #if CPPZMQ_HAS_STRING_VIEW
 // std::basic_string_view
 template<class T, class Traits>
 const_buffer buffer(std::basic_string_view<T, Traits> data) noexcept
 {
     return detail::buffer_contiguous_sequence(data);
 }
 template<class T, class Traits>
 const_buffer buffer(std::basic_string_view<T, Traits> data, size_t n_bytes) noexcept
 {
     return detail::buffer_contiguous_sequence(data, n_bytes);
 }
 #endif
 
 // Buffer for a string literal (null terminated)
 // where the buffer size excludes the terminating character.
 // Equivalent to zmq::buffer(std::string_view("...")).
 template<class Char, size_t N>
 constexpr const_buffer str_buffer(const Char (&data)[N]) noexcept
 {
     static_assert(detail::is_pod_like<Char>::value, "Char must be POD");
 #ifdef ZMQ_EXTENDED_CONSTEXPR
     assert(data[N - 1] == Char{0});
 #endif
     return const_buffer(static_cast<const Char *>(data), (N - 1) * sizeof(Char));
 }
 
 namespace literals
 {
 constexpr const_buffer operator"" _zbuf(const char *str, size_t len) noexcept
 {
     return const_buffer(str, len * sizeof(char));
 }
 constexpr const_buffer operator"" _zbuf(const wchar_t *str, size_t len) noexcept
 {
     return const_buffer(str, len * sizeof(wchar_t));
 }
 constexpr const_buffer operator"" _zbuf(const char16_t *str, size_t len) noexcept
 {
     return const_buffer(str, len * sizeof(char16_t));
 }
 constexpr const_buffer operator"" _zbuf(const char32_t *str, size_t len) noexcept
 {
     return const_buffer(str, len * sizeof(char32_t));
 }
 }
 
 #ifdef ZMQ_CPP11
 enum class socket_type : int
 {
     req = ZMQ_REQ,
     rep = ZMQ_REP,
     dealer = ZMQ_DEALER,
     router = ZMQ_ROUTER,
     pub = ZMQ_PUB,
     sub = ZMQ_SUB,
     xpub = ZMQ_XPUB,
     xsub = ZMQ_XSUB,
     push = ZMQ_PUSH,
     pull = ZMQ_PULL,
 #if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
     server = ZMQ_SERVER,
     client = ZMQ_CLIENT,
     radio = ZMQ_RADIO,
     dish = ZMQ_DISH,
     gather = ZMQ_GATHER,
     scatter = ZMQ_SCATTER,
     dgram = ZMQ_DGRAM,
 #endif
 #if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 3, 3)
     peer = ZMQ_PEER,
     channel = ZMQ_CHANNEL,
 #endif
 #if ZMQ_VERSION_MAJOR >= 4
     stream = ZMQ_STREAM,
 #endif
     pair = ZMQ_PAIR
 };
 #endif
 
 namespace sockopt
 {
 // There are two types of options,
 // integral type with known compiler time size (int, bool, int64_t, uint64_t)
 // and arrays with dynamic size (strings, binary data).
 
 // BoolUnit: if true accepts values of type bool (but passed as T into libzmq)
 template<int Opt, class T, bool BoolUnit = false> struct integral_option
 {
 };
 
 // NullTerm:
 // 0: binary data
 // 1: null-terminated string (`getsockopt` size includes null)
 // 2: binary (size 32) or Z85 encoder string of size 41 (null included)
 template<int Opt, int NullTerm = 1> struct array_option
 {
 };
 
 #define ZMQ_DEFINE_INTEGRAL_OPT(OPT, NAME, TYPE)                                    \
     using NAME##_t = integral_option<OPT, TYPE, false>;                             \
     ZMQ_INLINE_VAR ZMQ_CONSTEXPR_VAR NAME##_t NAME {}
 #define ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(OPT, NAME, TYPE)                          \
     using NAME##_t = integral_option<OPT, TYPE, true>;                              \
     ZMQ_INLINE_VAR ZMQ_CONSTEXPR_VAR NAME##_t NAME {}
 #define ZMQ_DEFINE_ARRAY_OPT(OPT, NAME)                                             \
     using NAME##_t = array_option<OPT>;                                             \
     ZMQ_INLINE_VAR ZMQ_CONSTEXPR_VAR NAME##_t NAME {}
 #define ZMQ_DEFINE_ARRAY_OPT_BINARY(OPT, NAME)                                      \
     using NAME##_t = array_option<OPT, 0>;                                          \
     ZMQ_INLINE_VAR ZMQ_CONSTEXPR_VAR NAME##_t NAME {}
 #define ZMQ_DEFINE_ARRAY_OPT_BIN_OR_Z85(OPT, NAME)                                  \
     using NAME##_t = array_option<OPT, 2>;                                          \
     ZMQ_INLINE_VAR ZMQ_CONSTEXPR_VAR NAME##_t NAME {}
 
 // deprecated, use zmq::fd_t
 using cppzmq_fd_t = ::zmq::fd_t;
 
 #ifdef ZMQ_AFFINITY
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_AFFINITY, affinity, uint64_t);
 #endif
 #ifdef ZMQ_BACKLOG
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_BACKLOG, backlog, int);
 #endif
 #ifdef ZMQ_BINDTODEVICE
 ZMQ_DEFINE_ARRAY_OPT_BINARY(ZMQ_BINDTODEVICE, bindtodevice);
 #endif
 #ifdef ZMQ_CONFLATE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_CONFLATE, conflate, int);
 #endif
 #ifdef ZMQ_CONNECT_ROUTING_ID
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_CONNECT_ROUTING_ID, connect_routing_id);
 #endif
 #ifdef ZMQ_CONNECT_TIMEOUT
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_CONNECT_TIMEOUT, connect_timeout, int);
 #endif
 #ifdef ZMQ_CURVE_PUBLICKEY
 ZMQ_DEFINE_ARRAY_OPT_BIN_OR_Z85(ZMQ_CURVE_PUBLICKEY, curve_publickey);
 #endif
 #ifdef ZMQ_CURVE_SECRETKEY
 ZMQ_DEFINE_ARRAY_OPT_BIN_OR_Z85(ZMQ_CURVE_SECRETKEY, curve_secretkey);
 #endif
 #ifdef ZMQ_CURVE_SERVER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_CURVE_SERVER, curve_server, int);
 #endif
 #ifdef ZMQ_CURVE_SERVERKEY
 ZMQ_DEFINE_ARRAY_OPT_BIN_OR_Z85(ZMQ_CURVE_SERVERKEY, curve_serverkey);
 #endif
 #ifdef ZMQ_EVENTS
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_EVENTS, events, int);
 #endif
 #ifdef ZMQ_FD
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_FD, fd, ::zmq::fd_t);
 #endif
 #ifdef ZMQ_GSSAPI_PLAINTEXT
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_GSSAPI_PLAINTEXT, gssapi_plaintext, int);
 #endif
 #ifdef ZMQ_GSSAPI_SERVER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_GSSAPI_SERVER, gssapi_server, int);
 #endif
 #ifdef ZMQ_GSSAPI_SERVICE_PRINCIPAL
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_GSSAPI_SERVICE_PRINCIPAL, gssapi_service_principal);
 #endif
 #ifdef ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE,
                         gssapi_service_principal_nametype,
                         int);
 #endif
 #ifdef ZMQ_GSSAPI_PRINCIPAL
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_GSSAPI_PRINCIPAL, gssapi_principal);
 #endif
 #ifdef ZMQ_GSSAPI_PRINCIPAL_NAMETYPE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_GSSAPI_PRINCIPAL_NAMETYPE,
                         gssapi_principal_nametype,
                         int);
 #endif
 #ifdef ZMQ_HANDSHAKE_IVL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_HANDSHAKE_IVL, handshake_ivl, int);
 #endif
 #ifdef ZMQ_HEARTBEAT_IVL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_HEARTBEAT_IVL, heartbeat_ivl, int);
 #endif
 #ifdef ZMQ_HEARTBEAT_TIMEOUT
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_HEARTBEAT_TIMEOUT, heartbeat_timeout, int);
 #endif
 #ifdef ZMQ_HEARTBEAT_TTL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_HEARTBEAT_TTL, heartbeat_ttl, int);
 #endif
 #ifdef ZMQ_IMMEDIATE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_IMMEDIATE, immediate, int);
 #endif
 #ifdef ZMQ_INVERT_MATCHING
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_INVERT_MATCHING, invert_matching, int);
 #endif
 #ifdef ZMQ_IPV6
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_IPV6, ipv6, int);
 #endif
 #ifdef ZMQ_LAST_ENDPOINT
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_LAST_ENDPOINT, last_endpoint);
 #endif
 #ifdef ZMQ_LINGER
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_LINGER, linger, int);
 #endif
 #ifdef ZMQ_MAXMSGSIZE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_MAXMSGSIZE, maxmsgsize, int64_t);
 #endif
 #ifdef ZMQ_MECHANISM
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_MECHANISM, mechanism, int);
 #endif
 #ifdef ZMQ_METADATA
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_METADATA, metadata);
 #endif
 #ifdef ZMQ_MULTICAST_HOPS
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_MULTICAST_HOPS, multicast_hops, int);
 #endif
 #ifdef ZMQ_MULTICAST_LOOP
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_MULTICAST_LOOP, multicast_loop, int);
 #endif
 #ifdef ZMQ_MULTICAST_MAXTPDU
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_MULTICAST_MAXTPDU, multicast_maxtpdu, int);
 #endif
 #ifdef ZMQ_ONLY_FIRST_SUBSCRIBE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_ONLY_FIRST_SUBSCRIBE, only_first_subscribe, int);
 #endif
 #ifdef ZMQ_PLAIN_SERVER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_PLAIN_SERVER, plain_server, int);
 #endif
 #ifdef ZMQ_PLAIN_PASSWORD
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_PLAIN_PASSWORD, plain_password);
 #endif
 #ifdef ZMQ_PLAIN_USERNAME
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_PLAIN_USERNAME, plain_username);
 #endif
 #ifdef ZMQ_USE_FD
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_USE_FD, use_fd, int);
 #endif
 #ifdef ZMQ_PROBE_ROUTER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_PROBE_ROUTER, probe_router, int);
 #endif
 #ifdef ZMQ_RATE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RATE, rate, int);
 #endif
 #ifdef ZMQ_RCVBUF
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RCVBUF, rcvbuf, int);
 #endif
 #ifdef ZMQ_RCVHWM
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RCVHWM, rcvhwm, int);
 #endif
 #ifdef ZMQ_RCVMORE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_RCVMORE, rcvmore, int);
 #endif
 #ifdef ZMQ_RCVTIMEO
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RCVTIMEO, rcvtimeo, int);
 #endif
 #ifdef ZMQ_RECONNECT_IVL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RECONNECT_IVL, reconnect_ivl, int);
 #endif
 #ifdef ZMQ_RECONNECT_IVL_MAX
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RECONNECT_IVL_MAX, reconnect_ivl_max, int);
 #endif
 #ifdef ZMQ_RECOVERY_IVL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_RECOVERY_IVL, recovery_ivl, int);
 #endif
 #ifdef ZMQ_REQ_CORRELATE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_REQ_CORRELATE, req_correlate, int);
 #endif
 #ifdef ZMQ_REQ_RELAXED
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_REQ_RELAXED, req_relaxed, int);
 #endif
 #ifdef ZMQ_ROUTER_HANDOVER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_ROUTER_HANDOVER, router_handover, int);
 #endif
 #ifdef ZMQ_ROUTER_MANDATORY
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_ROUTER_MANDATORY, router_mandatory, int);
 #endif
 #ifdef ZMQ_ROUTER_NOTIFY
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_ROUTER_NOTIFY, router_notify, int);
 #endif
 #ifdef ZMQ_ROUTING_ID
 ZMQ_DEFINE_ARRAY_OPT_BINARY(ZMQ_ROUTING_ID, routing_id);
 #endif
 #ifdef ZMQ_SNDBUF
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_SNDBUF, sndbuf, int);
 #endif
 #ifdef ZMQ_SNDHWM
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_SNDHWM, sndhwm, int);
 #endif
 #ifdef ZMQ_SNDTIMEO
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_SNDTIMEO, sndtimeo, int);
 #endif
 #ifdef ZMQ_SOCKS_PROXY
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_SOCKS_PROXY, socks_proxy);
 #endif
 #ifdef ZMQ_STREAM_NOTIFY
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_STREAM_NOTIFY, stream_notify, int);
 #endif
 #ifdef ZMQ_SUBSCRIBE
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_SUBSCRIBE, subscribe);
 #endif
 #ifdef ZMQ_TCP_KEEPALIVE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TCP_KEEPALIVE, tcp_keepalive, int);
 #endif
 #ifdef ZMQ_TCP_KEEPALIVE_CNT
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TCP_KEEPALIVE_CNT, tcp_keepalive_cnt, int);
 #endif
 #ifdef ZMQ_TCP_KEEPALIVE_IDLE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TCP_KEEPALIVE_IDLE, tcp_keepalive_idle, int);
 #endif
 #ifdef ZMQ_TCP_KEEPALIVE_INTVL
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TCP_KEEPALIVE_INTVL, tcp_keepalive_intvl, int);
 #endif
 #ifdef ZMQ_TCP_MAXRT
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TCP_MAXRT, tcp_maxrt, int);
 #endif
 #ifdef ZMQ_THREAD_SAFE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_THREAD_SAFE, thread_safe, int);
 #endif
 #ifdef ZMQ_TOS
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TOS, tos, int);
 #endif
 #ifdef ZMQ_TYPE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TYPE, type, int);
 #ifdef ZMQ_CPP11
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_TYPE, socket_type, socket_type);
 #endif // ZMQ_CPP11
 #endif // ZMQ_TYPE
 #ifdef ZMQ_UNSUBSCRIBE
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_UNSUBSCRIBE, unsubscribe);
 #endif
 #ifdef ZMQ_VMCI_BUFFER_SIZE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_VMCI_BUFFER_SIZE, vmci_buffer_size, uint64_t);
 #endif
 #ifdef ZMQ_VMCI_BUFFER_MIN_SIZE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_VMCI_BUFFER_MIN_SIZE, vmci_buffer_min_size, uint64_t);
 #endif
 #ifdef ZMQ_VMCI_BUFFER_MAX_SIZE
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_VMCI_BUFFER_MAX_SIZE, vmci_buffer_max_size, uint64_t);
 #endif
 #ifdef ZMQ_VMCI_CONNECT_TIMEOUT
 ZMQ_DEFINE_INTEGRAL_OPT(ZMQ_VMCI_CONNECT_TIMEOUT, vmci_connect_timeout, int);
 #endif
 #ifdef ZMQ_XPUB_VERBOSE
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_XPUB_VERBOSE, xpub_verbose, int);
 #endif
 #ifdef ZMQ_XPUB_VERBOSER
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_XPUB_VERBOSER, xpub_verboser, int);
 #endif
 #ifdef ZMQ_XPUB_MANUAL
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_XPUB_MANUAL, xpub_manual, int);
 #endif
 #ifdef ZMQ_XPUB_NODROP
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_XPUB_NODROP, xpub_nodrop, int);
 #endif
 #ifdef ZMQ_XPUB_WELCOME_MSG
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_XPUB_WELCOME_MSG, xpub_welcome_msg);
 #endif
 #ifdef ZMQ_ZAP_ENFORCE_DOMAIN
 ZMQ_DEFINE_INTEGRAL_BOOL_UNIT_OPT(ZMQ_ZAP_ENFORCE_DOMAIN, zap_enforce_domain, int);
 #endif
 #ifdef ZMQ_ZAP_DOMAIN
 ZMQ_DEFINE_ARRAY_OPT(ZMQ_ZAP_DOMAIN, zap_domain);
 #endif
 
 } // namespace sockopt
 #endif // ZMQ_CPP11
 
 
 namespace detail
 {
 class socket_base
 {
   public:
     socket_base() ZMQ_NOTHROW : _handle(ZMQ_NULLPTR) {}
     ZMQ_EXPLICIT socket_base(void *handle) ZMQ_NOTHROW : _handle(handle) {}
 
     template<typename T>
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use `set` taking option from zmq::sockopt")
     void setsockopt(int option_, T const &optval)
     {
         setsockopt(option_, &optval, sizeof(T));
     }
 
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use `set` taking option from zmq::sockopt")
     void setsockopt(int option_, const void *optval_, size_t optvallen_)
     {
         int rc = zmq_setsockopt(_handle, option_, optval_, optvallen_);
         if (rc != 0)
             throw error_t();
     }
 
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use `get` taking option from zmq::sockopt")
     void getsockopt(int option_, void *optval_, size_t *optvallen_) const
     {
         int rc = zmq_getsockopt(_handle, option_, optval_, optvallen_);
         if (rc != 0)
             throw error_t();
     }
 
     template<typename T>
     ZMQ_CPP11_DEPRECATED("from 4.7.0, use `get` taking option from zmq::sockopt")
     T getsockopt(int option_) const
     {
         T optval;
         size_t optlen = sizeof(T);
         getsockopt(option_, &optval, &optlen);
         return optval;
     }
 
 #ifdef ZMQ_CPP11
     // Set integral socket option, e.g.
     // `socket.set(zmq::sockopt::linger, 0)`
     template<int Opt, class T, bool BoolUnit>
     void set(sockopt::integral_option<Opt, T, BoolUnit>, const T &val)
     {
         static_assert(std::is_integral<T>::value, "T must be integral");
         set_option(Opt, &val, sizeof val);
     }
 
     // Set integral socket option from boolean, e.g.
     // `socket.set(zmq::sockopt::immediate, false)`
     template<int Opt, class T>
     void set(sockopt::integral_option<Opt, T, true>, bool val)
     {
         static_assert(std::is_integral<T>::value, "T must be integral");
         T rep_val = val;
         set_option(Opt, &rep_val, sizeof rep_val);
     }
 
     // Set array socket option, e.g.
     // `socket.set(zmq::sockopt::plain_username, "foo123")`
     template<int Opt, int NullTerm>
     void set(sockopt::array_option<Opt, NullTerm>, const char *buf)
     {
         set_option(Opt, buf, std::strlen(buf));
     }
 
     // Set array socket option, e.g.
     // `socket.set(zmq::sockopt::routing_id, zmq::buffer(id))`
     template<int Opt, int NullTerm>
     void set(sockopt::array_option<Opt, NullTerm>, const_buffer buf)
     {
         set_option(Opt, buf.data(), buf.size());
     }
 
     // Set array socket option, e.g.
     // `socket.set(zmq::sockopt::routing_id, id_str)`
     template<int Opt, int NullTerm>
     void set(sockopt::array_option<Opt, NullTerm>, const std::string &buf)
     {
         set_option(Opt, buf.data(), buf.size());
     }
 
 #if CPPZMQ_HAS_STRING_VIEW
     // Set array socket option, e.g.
     // `socket.set(zmq::sockopt::routing_id, id_str)`
     template<int Opt, int NullTerm>
     void set(sockopt::array_option<Opt, NullTerm>, std::string_view buf)
     {
         set_option(Opt, buf.data(), buf.size());
     }
 #endif
 
     // Get scalar socket option, e.g.
     // `auto opt = socket.get(zmq::sockopt::linger)`
     template<int Opt, class T, bool BoolUnit>
     ZMQ_NODISCARD T get(sockopt::integral_option<Opt, T, BoolUnit>) const
     {
         static_assert(std::is_scalar<T>::value, "T must be scalar");
         T val;
         size_t size = sizeof val;
         get_option(Opt, &val, &size);
         assert(size == sizeof val);
         return val;
     }
 
     // Get array socket option, writes to buf, returns option size in bytes, e.g.
     // `size_t optsize = socket.get(zmq::sockopt::routing_id, zmq::buffer(id))`
     template<int Opt, int NullTerm>
     ZMQ_NODISCARD size_t get(sockopt::array_option<Opt, NullTerm>,
                              mutable_buffer buf) const
     {
         size_t size = buf.size();
         get_option(Opt, buf.data(), &size);
         return size;
     }
 
     // Get array socket option as string (initializes the string buffer size to init_size) e.g.
     // `auto s = socket.get(zmq::sockopt::routing_id)`
     // Note: removes the null character from null-terminated string options,
     // i.e. the string size excludes the null character.
     template<int Opt, int NullTerm>
     ZMQ_NODISCARD std::string get(sockopt::array_option<Opt, NullTerm>,
                                   size_t init_size = 1024) const
     {
         if ZMQ_CONSTEXPR_IF (NullTerm == 2) {
             if (init_size == 1024) {
                 init_size = 41; // get as Z85 string
             }
         }
         std::string str(init_size, '\0');
         size_t size = get(sockopt::array_option<Opt>{}, buffer(str));
         if ZMQ_CONSTEXPR_IF (NullTerm == 1) {
             if (size > 0) {
                 assert(str[size - 1] == '\0');
                 --size;
             }
         } else if ZMQ_CONSTEXPR_IF (NullTerm == 2) {
             assert(size == 32 || size == 41);
             if (size == 41) {
                 assert(str[size - 1] == '\0');
                 --size;
             }
         }
         str.resize(size);
         return str;
     }
 #endif
 
     void bind(std::string const &addr) { bind(addr.c_str()); }
 
     void bind(const char *addr_)
     {
         int rc = zmq_bind(_handle, addr_);
         if (rc != 0)
             throw error_t();
     }
 
     void unbind(std::string const &addr) { unbind(addr.c_str()); }
 
     void unbind(const char *addr_)
     {
         int rc = zmq_unbind(_handle, addr_);
         if (rc != 0)
             throw error_t();
     }
 
     void connect(std::string const &addr) { connect(addr.c_str()); }
 
     void connect(const char *addr_)
     {
         int rc = zmq_connect(_handle, addr_);
         if (rc != 0)
             throw error_t();
     }
 
     void disconnect(std::string const &addr) { disconnect(addr.c_str()); }
 
     void disconnect(const char *addr_)
     {
         int rc = zmq_disconnect(_handle, addr_);
         if (rc != 0)
             throw error_t();
     }
 
     ZMQ_DEPRECATED("from 4.7.1, use handle() != nullptr or operator bool")
     bool connected() const ZMQ_NOTHROW { return (_handle != ZMQ_NULLPTR); }
 
     ZMQ_CPP11_DEPRECATED("from 4.3.1, use send taking a const_buffer and send_flags")
     size_t send(const void *buf_, size_t len_, int flags_ = 0)
     {
         int nbytes = zmq_send(_handle, buf_, len_, flags_);
         if (nbytes >= 0)
             return static_cast<size_t>(nbytes);
         if (zmq_errno() == EAGAIN)
             return 0;
         throw error_t();
     }
 
     ZMQ_CPP11_DEPRECATED("from 4.3.1, use send taking message_t and send_flags")
     bool send(message_t &msg_,
               int flags_ = 0) // default until removed
     {
         int nbytes = zmq_msg_send(msg_.handle(), _handle, flags_);
         if (nbytes >= 0)
             return true;
         if (zmq_errno() == EAGAIN)
             return false;
         throw error_t();
     }
 
     template<typename T>
     ZMQ_CPP11_DEPRECATED(
       "from 4.4.1, use send taking message_t or buffer (for contiguous "
       "ranges), and send_flags")
     bool send(T first, T last, int flags_ = 0)
     {
         zmq::message_t msg(first, last);
         int nbytes = zmq_msg_send(msg.handle(), _handle, flags_);
         if (nbytes >= 0)
             return true;
         if (zmq_errno() == EAGAIN)
             return false;
         throw error_t();
     }
 
 #ifdef ZMQ_HAS_RVALUE_REFS
     ZMQ_CPP11_DEPRECATED("from 4.3.1, use send taking message_t and send_flags")
     bool send(message_t &&msg_,
               int flags_ = 0) // default until removed
     {
 #ifdef ZMQ_CPP11
         return send(msg_, static_cast<send_flags>(flags_)).has_value();
 #else
         return send(msg_, flags_);
 #endif
     }
 #endif
 
 #ifdef ZMQ_CPP11
     send_result_t send(const_buffer buf, send_flags flags = send_flags::none)
     {
         const int nbytes =
           zmq_send(_handle, buf.data(), buf.size(), static_cast<int>(flags));
         if (nbytes >= 0)
             return static_cast<size_t>(nbytes);
         if (zmq_errno() == EAGAIN)
             return {};
         throw error_t();
     }
 
     send_result_t send(message_t &msg, send_flags flags)
     {
         int nbytes = zmq_msg_send(msg.handle(), _handle, static_cast<int>(flags));
         if (nbytes >= 0)
             return static_cast<size_t>(nbytes);
         if (zmq_errno() == EAGAIN)
             return {};
         throw error_t();
     }
 
     send_result_t send(message_t &&msg, send_flags flags)
     {
         return send(msg, flags);
     }
 #endif
 
     ZMQ_CPP11_DEPRECATED(
       "from 4.3.1, use recv taking a mutable_buffer and recv_flags")
     size_t recv(void *buf_, size_t len_, int flags_ = 0)
     {
         int nbytes = zmq_recv(_handle, buf_, len_, flags_);
         if (nbytes >= 0)
             return static_cast<size_t>(nbytes);
         if (zmq_errno() == EAGAIN)
             return 0;
         throw error_t();
     }
 
     ZMQ_CPP11_DEPRECATED(
       "from 4.3.1, use recv taking a reference to message_t and recv_flags")
     bool recv(message_t *msg_, int flags_ = 0)
     {
         int nbytes = zmq_msg_recv(msg_->handle(), _handle, flags_);
         if (nbytes >= 0)
             return true;
         if (zmq_errno() == EAGAIN)
             return false;
         throw error_t();
     }
 
 #ifdef ZMQ_CPP11
     ZMQ_NODISCARD
     recv_buffer_result_t recv(mutable_buffer buf,
                               recv_flags flags = recv_flags::none)
     {
         const int nbytes =
           zmq_recv(_handle, buf.data(), buf.size(), static_cast<int>(flags));
         if (nbytes >= 0) {
             return recv_buffer_size{
               (std::min)(static_cast<size_t>(nbytes), buf.size()),
               static_cast<size_t>(nbytes)};
         }
         if (zmq_errno() == EAGAIN)
             return {};
         throw error_t();
     }
 
     ZMQ_NODISCARD
     recv_result_t recv(message_t &msg, recv_flags flags = recv_flags::none)
     {
         const int nbytes =
           zmq_msg_recv(msg.handle(), _handle, static_cast<int>(flags));
         if (nbytes >= 0) {
             assert(msg.size() == static_cast<size_t>(nbytes));
             return static_cast<size_t>(nbytes);
         }
         if (zmq_errno() == EAGAIN)
             return {};
         throw error_t();
     }
 #endif
 
 #if defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 0)
     void join(const char *group)
     {
         int rc = zmq_join(_handle, group);
         if (rc != 0)
             throw error_t();
     }
 
     void leave(const char *group)
     {
         int rc = zmq_leave(_handle, group);
         if (rc != 0)
             throw error_t();
     }
 #endif
 
     ZMQ_NODISCARD void *handle() ZMQ_NOTHROW { return _handle; }
     ZMQ_NODISCARD const void *handle() const ZMQ_NOTHROW { return _handle; }
 
     ZMQ_EXPLICIT operator bool() const ZMQ_NOTHROW { return _handle != ZMQ_NULLPTR; }
     // note: non-const operator bool can be removed once
     // operator void* is removed from socket_t
     ZMQ_EXPLICIT operator bool() ZMQ_NOTHROW { return _handle != ZMQ_NULLPTR; }
 
   protected:
     void *_handle;
 
   private:
     void set_option(int option_, const void *optval_, size_t optvallen_)
     {
         int rc = zmq_setsockopt(_handle, option_, optval_, optvallen_);
         if (rc != 0)
             throw error_t();
     }
 
     void get_option(int option_, void *optval_, size_t *optvallen_) const
     {
         int rc = zmq_getsockopt(_handle, option_, optval_, optvallen_);
         if (rc != 0)
             throw error_t();
     }
 };
 } // namespace detail
 
 struct from_handle_t
 {
     struct _private
     {
     }; // disabling use other than with from_handle
     ZMQ_CONSTEXPR_FN ZMQ_EXPLICIT from_handle_t(_private /*p*/) ZMQ_NOTHROW {}
 };
 
 ZMQ_CONSTEXPR_VAR from_handle_t from_handle =
   from_handle_t(from_handle_t::_private());
 
 // A non-owning nullable reference to a socket.
 // The reference is invalidated on socket close or destruction.
 class socket_ref : public detail::socket_base
 {
   public:
     socket_ref() ZMQ_NOTHROW : detail::socket_base() {}
 #ifdef ZMQ_CPP11
     socket_ref(std::nullptr_t) ZMQ_NOTHROW : detail::socket_base() {}
 #endif
     socket_ref(from_handle_t /*fh*/, void *handle) ZMQ_NOTHROW
         : detail::socket_base(handle)
     {
     }
 };
 
 #ifdef ZMQ_CPP11
 inline bool operator==(socket_ref sr, std::nullptr_t /*p*/) ZMQ_NOTHROW
 {
     return sr.handle() == nullptr;
 }
 inline bool operator==(std::nullptr_t /*p*/, socket_ref sr) ZMQ_NOTHROW
 {
     return sr.handle() == nullptr;
 }
 inline bool operator!=(socket_ref sr, std::nullptr_t /*p*/) ZMQ_NOTHROW
 {
     return !(sr == nullptr);
 }
 inline bool operator!=(std::nullptr_t /*p*/, socket_ref sr) ZMQ_NOTHROW
 {
     return !(sr == nullptr);
 }
 #endif
 
 inline bool operator==(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return std::equal_to<const void *>()(a.handle(), b.handle());
 }
 inline bool operator!=(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return !(a == b);
 }
 inline bool operator<(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return std::less<const void *>()(a.handle(), b.handle());
 }
 inline bool operator>(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return b < a;
 }
 inline bool operator<=(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return !(a > b);
 }
 inline bool operator>=(const detail::socket_base& a, const detail::socket_base& b) ZMQ_NOTHROW
 {
     return !(a < b);
 }
 
 } // namespace zmq
 
 #ifdef ZMQ_CPP11
 namespace std
 {
 template<> struct hash<zmq::socket_ref>
 {
     size_t operator()(zmq::socket_ref sr) const ZMQ_NOTHROW
     {
         return hash<void *>()(sr.handle());
     }
 };
 } // namespace std
 #endif
 
 namespace zmq
 {
 class socket_t : public detail::socket_base
 {
     friend class monitor_t;
 
   public:
     socket_t() ZMQ_NOTHROW : detail::socket_base(ZMQ_NULLPTR), ctxptr(ZMQ_NULLPTR) {}
 
     socket_t(context_t &context_, int type_) :
         detail::socket_base(zmq_socket(context_.handle(), type_)),
         ctxptr(context_.handle())
     {
         if (_handle == ZMQ_NULLPTR)
             throw error_t();
     }
 
 #ifdef ZMQ_CPP11
     socket_t(context_t &context_, socket_type type_) :
         socket_t(context_, static_cast<int>(type_))
     {
     }
 #endif
 
 #ifdef ZMQ_HAS_RVALUE_REFS
     socket_t(socket_t &&rhs) ZMQ_NOTHROW : detail::socket_base(rhs._handle),
                                            ctxptr(rhs.ctxptr)
     {
         rhs._handle = ZMQ_NULLPTR;
         rhs.ctxptr = ZMQ_NULLPTR;
     }
     socket_t &operator=(socket_t &&rhs) ZMQ_NOTHROW
     {
         close();
         std::swap(_handle, rhs._handle);
         std::swap(ctxptr, rhs.ctxptr);
         return *this;
     }
 #endif
 
     ~socket_t() ZMQ_NOTHROW { close(); }
 
     operator void *() ZMQ_NOTHROW { return _handle; }
 
     operator void const *() const ZMQ_NOTHROW { return _handle; }
 
     void close() ZMQ_NOTHROW
     {
         if (_handle == ZMQ_NULLPTR)
             // already closed
             return;
         int rc = zmq_close(_handle);
         ZMQ_ASSERT(rc == 0);
         _handle = ZMQ_NULLPTR;
         ctxptr = ZMQ_NULLPTR;
     }
 
     void swap(socket_t &other) ZMQ_NOTHROW
     {
         std::swap(_handle, other._handle);
         std::swap(ctxptr, other.ctxptr);
     }
 
     operator socket_ref() ZMQ_NOTHROW { return socket_ref(from_handle, _handle); }
 
   private:
     void *ctxptr;
 
     socket_t(const socket_t &) ZMQ_DELETED_FUNCTION;
     void operator=(const socket_t &) ZMQ_DELETED_FUNCTION;
 
     // used by monitor_t
     socket_t(void *context_, int type_) :
         detail::socket_base(zmq_socket(context_, type_)), ctxptr(context_)
     {
         if (_handle == ZMQ_NULLPTR)
             throw error_t();
         if (ctxptr == ZMQ_NULLPTR)
             throw error_t();
     }
 };
 
 inline void swap(socket_t &a, socket_t &b) ZMQ_NOTHROW
 {
     a.swap(b);
 }
 
 ZMQ_DEPRECATED("from 4.3.1, use proxy taking socket_t objects")
 inline void proxy(void *frontend, void *backend, void *capture)
 {
     int rc = zmq_proxy(frontend, backend, capture);
     if (rc != 0)
         throw error_t();
 }
 
 inline void
 proxy(socket_ref frontend, socket_ref backend, socket_ref capture = socket_ref())
 {
     int rc = zmq_proxy(frontend.handle(), backend.handle(), capture.handle());
     if (rc != 0)
         throw error_t();
 }
 
 #ifdef ZMQ_HAS_PROXY_STEERABLE
 ZMQ_DEPRECATED("from 4.3.1, use proxy_steerable taking socket_t objects")
 inline void
 proxy_steerable(void *frontend, void *backend, void *capture, void *control)
 {
     int rc = zmq_proxy_steerable(frontend, backend, capture, control);
     if (rc != 0)
         throw error_t();
 }
 
 inline void proxy_steerable(socket_ref frontend,
                             socket_ref backend,
                             socket_ref capture,
                             socket_ref control)
 {
     int rc = zmq_proxy_steerable(frontend.handle(), backend.handle(),
                                  capture.handle(), control.handle());
     if (rc != 0)
         throw error_t();
 }
 #endif
 
 class monitor_t
 {
   public:
     monitor_t() : _socket(), _monitor_socket() {}
 
     virtual ~monitor_t() { close(); }
 
 #ifdef ZMQ_HAS_RVALUE_REFS
     monitor_t(monitor_t &&rhs) ZMQ_NOTHROW : _socket(), _monitor_socket()
     {
         std::swap(_socket, rhs._socket);
         std::swap(_monitor_socket, rhs._monitor_socket);
     }
 
     monitor_t &operator=(monitor_t &&rhs) ZMQ_NOTHROW
     {
         close();
         _socket = socket_ref();
         std::swap(_socket, rhs._socket);
         std::swap(_monitor_socket, rhs._monitor_socket);
         return *this;
     }
 #endif
 
 
     void
     monitor(socket_t &socket, std::string const &addr, int events = ZMQ_EVENT_ALL)
     {
         monitor(socket, addr.c_str(), events);
     }
 
     void monitor(socket_t &socket, const char *addr_, int events = ZMQ_EVENT_ALL)
     {
         init(socket, addr_, events);
         while (true) {
             check_event(-1);
         }
     }
 
     void init(socket_t &socket, std::string const &addr, int events = ZMQ_EVENT_ALL)
     {
         init(socket, addr.c_str(), events);
     }
 
     void init(socket_t &socket, const char *addr_, int events = ZMQ_EVENT_ALL)
     {
         int rc = zmq_socket_monitor(socket.handle(), addr_, events);
         if (rc != 0)
             throw error_t();
 
         _socket = socket;
         _monitor_socket = socket_t(socket.ctxptr, ZMQ_PAIR);
         _monitor_socket.connect(addr_);
 
         on_monitor_started();
     }
 
     bool check_event(int timeout = 0)
     {
         assert(_monitor_socket);
 
         zmq::message_t eventMsg;
 
         zmq::pollitem_t items[] = {
           {_monitor_socket.handle(), 0, ZMQ_POLLIN, 0},
         };
 
         #ifdef ZMQ_CPP11
         zmq::poll(&items[0], 1, std::chrono::milliseconds(timeout));
         #else
         zmq::poll(&items[0], 1, timeout);
         #endif
 
         if (items[0].revents & ZMQ_POLLIN) {
             int rc = zmq_msg_recv(eventMsg.handle(), _monitor_socket.handle(), 0);
             if (rc == -1 && zmq_errno() == ETERM)
                 return false;
             assert(rc != -1);
 
         } else {
             return false;
         }
 
 #if ZMQ_VERSION_MAJOR >= 4
         const char *data = static_cast<const char *>(eventMsg.data());
         zmq_event_t msgEvent;
         memcpy(&msgEvent.event, data, sizeof(uint16_t));
         data += sizeof(uint16_t);
         memcpy(&msgEvent.value, data, sizeof(int32_t));
         zmq_event_t *event = &msgEvent;
 #else
         zmq_event_t *event = static_cast<zmq_event_t *>(eventMsg.data());
 #endif
 
 #ifdef ZMQ_NEW_MONITOR_EVENT_LAYOUT
         zmq::message_t addrMsg;
         int rc = zmq_msg_recv(addrMsg.handle(), _monitor_socket.handle(), 0);
         if (rc == -1 && zmq_errno() == ETERM) {
             return false;
         }
 
         assert(rc != -1);
         std::string address = addrMsg.to_string();
 #else
         // Bit of a hack, but all events in the zmq_event_t union have the same layout so this will work for all event types.
         std::string address = event->data.connected.addr;
 #endif
 
 #ifdef ZMQ_EVENT_MONITOR_STOPPED
         if (event->event == ZMQ_EVENT_MONITOR_STOPPED) {
             return false;
         }
 
 #endif
 
         switch (event->event) {
             case ZMQ_EVENT_CONNECTED:
                 on_event_connected(*event, address.c_str());
                 break;
             case ZMQ_EVENT_CONNECT_DELAYED:
                 on_event_connect_delayed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_CONNECT_RETRIED:
                 on_event_connect_retried(*event, address.c_str());
                 break;
             case ZMQ_EVENT_LISTENING:
                 on_event_listening(*event, address.c_str());
                 break;
             case ZMQ_EVENT_BIND_FAILED:
                 on_event_bind_failed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_ACCEPTED:
                 on_event_accepted(*event, address.c_str());
                 break;
             case ZMQ_EVENT_ACCEPT_FAILED:
                 on_event_accept_failed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_CLOSED:
                 on_event_closed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_CLOSE_FAILED:
                 on_event_close_failed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_DISCONNECTED:
                 on_event_disconnected(*event, address.c_str());
                 break;
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 3, 0) || (defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3))
             case ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL:
                 on_event_handshake_failed_no_detail(*event, address.c_str());
                 break;
             case ZMQ_EVENT_HANDSHAKE_FAILED_PROTOCOL:
                 on_event_handshake_failed_protocol(*event, address.c_str());
                 break;
             case ZMQ_EVENT_HANDSHAKE_FAILED_AUTH:
                 on_event_handshake_failed_auth(*event, address.c_str());
                 break;
             case ZMQ_EVENT_HANDSHAKE_SUCCEEDED:
                 on_event_handshake_succeeded(*event, address.c_str());
                 break;
 #elif defined(ZMQ_BUILD_DRAFT_API) && ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 1)
             case ZMQ_EVENT_HANDSHAKE_FAILED:
                 on_event_handshake_failed(*event, address.c_str());
                 break;
             case ZMQ_EVENT_HANDSHAKE_SUCCEED:
                 on_event_handshake_succeed(*event, address.c_str());
                 break;
 #endif
             default:
                 on_event_unknown(*event, address.c_str());
                 break;
         }
 
         return true;
     }
 
 #ifdef ZMQ_EVENT_MONITOR_STOPPED
     void abort()
     {
         if (_socket)
             zmq_socket_monitor(_socket.handle(), ZMQ_NULLPTR, 0);
 
         _socket = socket_ref();
     }
 #endif
     virtual void on_monitor_started() {}
     virtual void on_event_connected(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_connect_delayed(const zmq_event_t &event_,
                                           const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_connect_retried(const zmq_event_t &event_,
                                           const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_listening(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_bind_failed(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_accepted(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_accept_failed(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_closed(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_close_failed(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_disconnected(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3)
     virtual void on_event_handshake_failed_no_detail(const zmq_event_t &event_,
                                                      const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_handshake_failed_protocol(const zmq_event_t &event_,
                                                     const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_handshake_failed_auth(const zmq_event_t &event_,
                                                 const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_handshake_succeeded(const zmq_event_t &event_,
                                               const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
 #elif ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 1)
     virtual void on_event_handshake_failed(const zmq_event_t &event_,
                                            const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
     virtual void on_event_handshake_succeed(const zmq_event_t &event_,
                                             const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
 #endif
     virtual void on_event_unknown(const zmq_event_t &event_, const char *addr_)
     {
         (void) event_;
         (void) addr_;
     }
 
   private:
     monitor_t(const monitor_t &) ZMQ_DELETED_FUNCTION;
     void operator=(const monitor_t &) ZMQ_DELETED_FUNCTION;
 
     socket_ref _socket;
     socket_t _monitor_socket;
 
     void close() ZMQ_NOTHROW
     {
         if (_socket)
             zmq_socket_monitor(_socket.handle(), ZMQ_NULLPTR, 0);
         _monitor_socket.close();
     }
 };
 
 #if defined(ZMQ_BUILD_DRAFT_API) && defined(ZMQ_CPP11) && defined(ZMQ_HAVE_POLLER)
 
 // polling events
 enum class event_flags : short
 {
     none = 0,
     pollin = ZMQ_POLLIN,
     pollout = ZMQ_POLLOUT,
     pollerr = ZMQ_POLLERR,
     pollpri = ZMQ_POLLPRI
 };
 
 constexpr event_flags operator|(event_flags a, event_flags b) noexcept
 {
     return detail::enum_bit_or(a, b);
 }
 constexpr event_flags operator&(event_flags a, event_flags b) noexcept
 {
     return detail::enum_bit_and(a, b);
 }
 constexpr event_flags operator^(event_flags a, event_flags b) noexcept
 {
     return detail::enum_bit_xor(a, b);
 }
 constexpr event_flags operator~(event_flags a) noexcept
 {
     return detail::enum_bit_not(a);
 }
 
 struct no_user_data;
 
 // layout compatible with zmq_poller_event_t
 template<class T = no_user_data> struct poller_event
 {
     socket_ref socket;
     ::zmq::fd_t fd;
     T *user_data;
     event_flags events;
 };
 
 template<typename T = no_user_data> class poller_t
 {
   public:
     using event_type = poller_event<T>;
 
     poller_t() : poller_ptr(zmq_poller_new())
     {
         if (!poller_ptr)
             throw error_t();
     }
 
     template<
       typename Dummy = void,
       typename =
         typename std::enable_if<!std::is_same<T, no_user_data>::value, Dummy>::type>
     void add(zmq::socket_ref socket, event_flags events, T *user_data)
     {
         add_impl(socket, events, user_data);
     }
 
     void add(zmq::socket_ref socket, event_flags events)
     {
         add_impl(socket, events, nullptr);
     }
 
     void remove(zmq::socket_ref socket)
     {
         if (0 != zmq_poller_remove(poller_ptr.get(), socket.handle())) {
             throw error_t();
         }
     }
 
     void modify(zmq::socket_ref socket, event_flags events)
     {
         if (0
             != zmq_poller_modify(poller_ptr.get(), socket.handle(),
                                  static_cast<short>(events))) {
             throw error_t();
         }
     }
 
     size_t wait_all(std::vector<event_type> &poller_events,
                     const std::chrono::milliseconds timeout)
     {
         int rc = zmq_poller_wait_all(
           poller_ptr.get(),
           reinterpret_cast<zmq_poller_event_t *>(poller_events.data()),
           static_cast<int>(poller_events.size()),
           static_cast<long>(timeout.count()));
         if (rc > 0)
             return static_cast<size_t>(rc);
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 2, 3)
         if (zmq_errno() == EAGAIN)
 #else
         if (zmq_errno() == ETIMEDOUT)
 #endif
             return 0;
 
         throw error_t();
     }
 
 #if ZMQ_VERSION >= ZMQ_MAKE_VERSION(4, 3, 3)
     size_t size() const noexcept
     {
         int rc = zmq_poller_size(const_cast<void *>(poller_ptr.get()));
         ZMQ_ASSERT(rc >= 0);
         return static_cast<size_t>(std::max(rc, 0));
     }
 #endif
 
   private:
     struct destroy_poller_t
     {
         void operator()(void *ptr) noexcept
         {
             int rc = zmq_poller_destroy(&ptr);
             ZMQ_ASSERT(rc == 0);
         }
     };
 
     std::unique_ptr<void, destroy_poller_t> poller_ptr;
 
     void add_impl(zmq::socket_ref socket, event_flags events, T *user_data)
     {
         if (0
             != zmq_poller_add(poller_ptr.get(), socket.handle(), user_data,
                               static_cast<short>(events))) {
             throw error_t();
         }
     }
 };
 #endif //  defined(ZMQ_BUILD_DRAFT_API) && defined(ZMQ_CPP11) && defined(ZMQ_HAVE_POLLER)
 
 inline std::ostream &operator<<(std::ostream &os, const message_t &msg)
 {
     return os << msg.str();
 }
 
 } // namespace zmq
 
 #endif // __ZMQ_HPP_INCLUDED__