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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 8
+#define CPPZMQ_VERSION_PATCH 1
+
+#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_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__