File indexing completed on 2025-02-16 05:12:19

 /*
     pybind11/pytypes.h: Convenience wrapper classes for basic Python types
 
     Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
 
     All rights reserved. Use of this source code is governed by a
     BSD-style license that can be found in the LICENSE file.
 */
 
 #pragma once
 
 #include "detail/common.h"
 #include "buffer_info.h"
 #include <utility>
 #include <type_traits>
 
 #if defined(PYBIND11_HAS_OPTIONAL)
 #  include <optional>
 #endif
 
 #ifdef PYBIND11_HAS_STRING_VIEW
 #  include <string_view>
 #endif
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 /* A few forward declarations */
 class handle; class object;
 class str; class iterator;
 class type;
 struct arg; struct arg_v;
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 class args_proxy;
 bool isinstance_generic(handle obj, const std::type_info &tp);
 
 // Accessor forward declarations
 template <typename Policy> class accessor;
 namespace accessor_policies {
     struct obj_attr;
     struct str_attr;
     struct generic_item;
     struct sequence_item;
     struct list_item;
     struct tuple_item;
 } // namespace accessor_policies
 using obj_attr_accessor = accessor<accessor_policies::obj_attr>;
 using str_attr_accessor = accessor<accessor_policies::str_attr>;
 using item_accessor = accessor<accessor_policies::generic_item>;
 using sequence_accessor = accessor<accessor_policies::sequence_item>;
 using list_accessor = accessor<accessor_policies::list_item>;
 using tuple_accessor = accessor<accessor_policies::tuple_item>;
 
 /// Tag and check to identify a class which implements the Python object API
 class pyobject_tag { };
 template <typename T> using is_pyobject = std::is_base_of<pyobject_tag, remove_reference_t<T>>;
 
 /** \rst
     A mixin class which adds common functions to `handle`, `object` and various accessors.
     The only requirement for `Derived` is to implement ``PyObject *Derived::ptr() const``.
 \endrst */
 template <typename Derived>
 class object_api : public pyobject_tag {
     const Derived &derived() const { return static_cast<const Derived &>(*this); }
 
 public:
     /** \rst
         Return an iterator equivalent to calling ``iter()`` in Python. The object
         must be a collection which supports the iteration protocol.
     \endrst */
     iterator begin() const;
     /// Return a sentinel which ends iteration.
     iterator end() const;
 
     /** \rst
         Return an internal functor to invoke the object's sequence protocol. Casting
         the returned ``detail::item_accessor`` instance to a `handle` or `object`
         subclass causes a corresponding call to ``__getitem__``. Assigning a `handle`
         or `object` subclass causes a call to ``__setitem__``.
     \endrst */
     item_accessor operator[](handle key) const;
     /// See above (the only difference is that they key is provided as a string literal)
     item_accessor operator[](const char *key) const;
 
     /** \rst
         Return an internal functor to access the object's attributes. Casting the
         returned ``detail::obj_attr_accessor`` instance to a `handle` or `object`
         subclass causes a corresponding call to ``getattr``. Assigning a `handle`
         or `object` subclass causes a call to ``setattr``.
     \endrst */
     obj_attr_accessor attr(handle key) const;
     /// See above (the only difference is that they key is provided as a string literal)
     str_attr_accessor attr(const char *key) const;
 
     /** \rst
         Matches * unpacking in Python, e.g. to unpack arguments out of a ``tuple``
         or ``list`` for a function call. Applying another * to the result yields
         ** unpacking, e.g. to unpack a dict as function keyword arguments.
         See :ref:`calling_python_functions`.
     \endrst */
     args_proxy operator*() const;
 
     /// Check if the given item is contained within this object, i.e. ``item in obj``.
     template <typename T> bool contains(T &&item) const;
 
     /** \rst
         Assuming the Python object is a function or implements the ``__call__``
         protocol, ``operator()`` invokes the underlying function, passing an
         arbitrary set of parameters. The result is returned as a `object` and
         may need to be converted back into a Python object using `handle::cast()`.
 
         When some of the arguments cannot be converted to Python objects, the
         function will throw a `cast_error` exception. When the Python function
         call fails, a `error_already_set` exception is thrown.
     \endrst */
     template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
     object operator()(Args &&...args) const;
     template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
     PYBIND11_DEPRECATED("call(...) was deprecated in favor of operator()(...)")
         object call(Args&&... args) const;
 
     /// Equivalent to ``obj is other`` in Python.
     bool is(object_api const& other) const { return derived().ptr() == other.derived().ptr(); }
     /// Equivalent to ``obj is None`` in Python.
     bool is_none() const { return derived().ptr() == Py_None; }
     /// Equivalent to obj == other in Python
     bool equal(object_api const &other) const      { return rich_compare(other, Py_EQ); }
     bool not_equal(object_api const &other) const  { return rich_compare(other, Py_NE); }
     bool operator<(object_api const &other) const  { return rich_compare(other, Py_LT); }
     bool operator<=(object_api const &other) const { return rich_compare(other, Py_LE); }
     bool operator>(object_api const &other) const  { return rich_compare(other, Py_GT); }
     bool operator>=(object_api const &other) const { return rich_compare(other, Py_GE); }
 
     object operator-() const;
     object operator~() const;
     object operator+(object_api const &other) const;
     object operator+=(object_api const &other) const;
     object operator-(object_api const &other) const;
     object operator-=(object_api const &other) const;
     object operator*(object_api const &other) const;
     object operator*=(object_api const &other) const;
     object operator/(object_api const &other) const;
     object operator/=(object_api const &other) const;
     object operator|(object_api const &other) const;
     object operator|=(object_api const &other) const;
     object operator&(object_api const &other) const;
     object operator&=(object_api const &other) const;
     object operator^(object_api const &other) const;
     object operator^=(object_api const &other) const;
     object operator<<(object_api const &other) const;
     object operator<<=(object_api const &other) const;
     object operator>>(object_api const &other) const;
     object operator>>=(object_api const &other) const;
 
     PYBIND11_DEPRECATED("Use py::str(obj) instead")
     pybind11::str str() const;
 
     /// Get or set the object's docstring, i.e. ``obj.__doc__``.
     str_attr_accessor doc() const;
 
     /// Return the object's current reference count
     int ref_count() const { return static_cast<int>(Py_REFCNT(derived().ptr())); }
 
     // TODO PYBIND11_DEPRECATED("Call py::type::handle_of(h) or py::type::of(h) instead of h.get_type()")
     handle get_type() const;
 
 private:
     bool rich_compare(object_api const &other, int value) const;
 };
 
 PYBIND11_NAMESPACE_END(detail)
 
 /** \rst
     Holds a reference to a Python object (no reference counting)
 
     The `handle` class is a thin wrapper around an arbitrary Python object (i.e. a
     ``PyObject *`` in Python's C API). It does not perform any automatic reference
     counting and merely provides a basic C++ interface to various Python API functions.
 
     .. seealso::
         The `object` class inherits from `handle` and adds automatic reference
         counting features.
 \endrst */
 class handle : public detail::object_api<handle> {
 public:
     /// The default constructor creates a handle with a ``nullptr``-valued pointer
     handle() = default;
     /// Creates a ``handle`` from the given raw Python object pointer
     // NOLINTNEXTLINE(google-explicit-constructor)
     handle(PyObject *ptr) : m_ptr(ptr) { } // Allow implicit conversion from PyObject*
 
     /// Return the underlying ``PyObject *`` pointer
     PyObject *ptr() const { return m_ptr; }
     PyObject *&ptr() { return m_ptr; }
 
     /** \rst
         Manually increase the reference count of the Python object. Usually, it is
         preferable to use the `object` class which derives from `handle` and calls
         this function automatically. Returns a reference to itself.
     \endrst */
     const handle& inc_ref() const & { Py_XINCREF(m_ptr); return *this; }
 
     /** \rst
         Manually decrease the reference count of the Python object. Usually, it is
         preferable to use the `object` class which derives from `handle` and calls
         this function automatically. Returns a reference to itself.
     \endrst */
     const handle& dec_ref() const & { Py_XDECREF(m_ptr); return *this; }
 
     /** \rst
         Attempt to cast the Python object into the given C++ type. A `cast_error`
         will be throw upon failure.
     \endrst */
     template <typename T> T cast() const;
     /// Return ``true`` when the `handle` wraps a valid Python object
     explicit operator bool() const { return m_ptr != nullptr; }
     /** \rst
         Deprecated: Check that the underlying pointers are the same.
         Equivalent to ``obj1 is obj2`` in Python.
     \endrst */
     PYBIND11_DEPRECATED("Use obj1.is(obj2) instead")
     bool operator==(const handle &h) const { return m_ptr == h.m_ptr; }
     PYBIND11_DEPRECATED("Use !obj1.is(obj2) instead")
     bool operator!=(const handle &h) const { return m_ptr != h.m_ptr; }
     PYBIND11_DEPRECATED("Use handle::operator bool() instead")
     bool check() const { return m_ptr != nullptr; }
 protected:
     PyObject *m_ptr = nullptr;
 };
 
 /** \rst
     Holds a reference to a Python object (with reference counting)
 
     Like `handle`, the `object` class is a thin wrapper around an arbitrary Python
     object (i.e. a ``PyObject *`` in Python's C API). In contrast to `handle`, it
     optionally increases the object's reference count upon construction, and it
     *always* decreases the reference count when the `object` instance goes out of
     scope and is destructed. When using `object` instances consistently, it is much
     easier to get reference counting right at the first attempt.
 \endrst */
 class object : public handle {
 public:
     object() = default;
     PYBIND11_DEPRECATED("Use reinterpret_borrow<object>() or reinterpret_steal<object>()")
     object(handle h, bool is_borrowed) : handle(h) { if (is_borrowed) inc_ref(); }
     /// Copy constructor; always increases the reference count
     object(const object &o) : handle(o) { inc_ref(); }
     /// Move constructor; steals the object from ``other`` and preserves its reference count
     object(object &&other) noexcept { m_ptr = other.m_ptr; other.m_ptr = nullptr; }
     /// Destructor; automatically calls `handle::dec_ref()`
     ~object() { dec_ref(); }
 
     /** \rst
         Resets the internal pointer to ``nullptr`` without decreasing the
         object's reference count. The function returns a raw handle to the original
         Python object.
     \endrst */
     handle release() {
       PyObject *tmp = m_ptr;
       m_ptr = nullptr;
       return handle(tmp);
     }
 
     object& operator=(const object &other) {
         other.inc_ref();
         // Use temporary variable to ensure `*this` remains valid while
         // `Py_XDECREF` executes, in case `*this` is accessible from Python.
         handle temp(m_ptr);
         m_ptr = other.m_ptr;
         temp.dec_ref();
         return *this;
     }
 
     object& operator=(object &&other) noexcept {
         if (this != &other) {
             handle temp(m_ptr);
             m_ptr = other.m_ptr;
             other.m_ptr = nullptr;
             temp.dec_ref();
         }
         return *this;
     }
 
     // Calling cast() on an object lvalue just copies (via handle::cast)
     template <typename T> T cast() const &;
     // Calling on an object rvalue does a move, if needed and/or possible
     template <typename T> T cast() &&;
 
 protected:
     // Tags for choosing constructors from raw PyObject *
     struct borrowed_t { };
     struct stolen_t { };
 
     /// @cond BROKEN
     template <typename T> friend T reinterpret_borrow(handle);
     template <typename T> friend T reinterpret_steal(handle);
     /// @endcond
 
 public:
     // Only accessible from derived classes and the reinterpret_* functions
     object(handle h, borrowed_t) : handle(h) { inc_ref(); }
     object(handle h, stolen_t) : handle(h) { }
 };
 
 /** \rst
     Declare that a `handle` or ``PyObject *`` is a certain type and borrow the reference.
     The target type ``T`` must be `object` or one of its derived classes. The function
     doesn't do any conversions or checks. It's up to the user to make sure that the
     target type is correct.
 
     .. code-block:: cpp
 
         PyObject *p = PyList_GetItem(obj, index);
         py::object o = reinterpret_borrow<py::object>(p);
         // or
         py::tuple t = reinterpret_borrow<py::tuple>(p); // <-- `p` must be already be a `tuple`
 \endrst */
 template <typename T> T reinterpret_borrow(handle h) { return {h, object::borrowed_t{}}; }
 
 /** \rst
     Like `reinterpret_borrow`, but steals the reference.
 
      .. code-block:: cpp
 
         PyObject *p = PyObject_Str(obj);
         py::str s = reinterpret_steal<py::str>(p); // <-- `p` must be already be a `str`
 \endrst */
 template <typename T> T reinterpret_steal(handle h) { return {h, object::stolen_t{}}; }
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 std::string error_string();
 PYBIND11_NAMESPACE_END(detail)
 
 #if defined(_MSC_VER)
 #  pragma warning(push)
 #  pragma warning(disable: 4275 4251) // warning C4275: An exported class was derived from a class that wasn't exported. Can be ignored when derived from a STL class.
 #endif
 /// Fetch and hold an error which was already set in Python.  An instance of this is typically
 /// thrown to propagate python-side errors back through C++ which can either be caught manually or
 /// else falls back to the function dispatcher (which then raises the captured error back to
 /// python).
 class PYBIND11_EXPORT_EXCEPTION error_already_set : public std::runtime_error {
 public:
     /// Constructs a new exception from the current Python error indicator, if any.  The current
     /// Python error indicator will be cleared.
     error_already_set() : std::runtime_error(detail::error_string()) {
         PyErr_Fetch(&m_type.ptr(), &m_value.ptr(), &m_trace.ptr());
     }
 
     error_already_set(const error_already_set &) = default;
     error_already_set(error_already_set &&) = default;
 
     inline ~error_already_set() override;
 
     /// Give the currently-held error back to Python, if any.  If there is currently a Python error
     /// already set it is cleared first.  After this call, the current object no longer stores the
     /// error variables (but the `.what()` string is still available).
     void restore() { PyErr_Restore(m_type.release().ptr(), m_value.release().ptr(), m_trace.release().ptr()); }
 
     /// If it is impossible to raise the currently-held error, such as in a destructor, we can write
     /// it out using Python's unraisable hook (`sys.unraisablehook`). The error context should be
     /// some object whose `repr()` helps identify the location of the error. Python already knows the
     /// type and value of the error, so there is no need to repeat that. After this call, the current
     /// object no longer stores the error variables, and neither does Python.
     void discard_as_unraisable(object err_context) {
         restore();
         PyErr_WriteUnraisable(err_context.ptr());
     }
     /// An alternate version of `discard_as_unraisable()`, where a string provides information on the
     /// location of the error. For example, `__func__` could be helpful.
     void discard_as_unraisable(const char *err_context) {
         discard_as_unraisable(reinterpret_steal<object>(PYBIND11_FROM_STRING(err_context)));
     }
 
     // Does nothing; provided for backwards compatibility.
     PYBIND11_DEPRECATED("Use of error_already_set.clear() is deprecated")
     void clear() {}
 
     /// Check if the currently trapped error type matches the given Python exception class (or a
     /// subclass thereof).  May also be passed a tuple to search for any exception class matches in
     /// the given tuple.
     bool matches(handle exc) const {
         return (PyErr_GivenExceptionMatches(m_type.ptr(), exc.ptr()) != 0);
     }
 
     const object& type() const { return m_type; }
     const object& value() const { return m_value; }
     const object& trace() const { return m_trace; }
 
 private:
     object m_type, m_value, m_trace;
 };
 #if defined(_MSC_VER)
 #  pragma warning(pop)
 #endif
 
 #if PY_VERSION_HEX >= 0x03030000
 
 /// Replaces the current Python error indicator with the chosen error, performing a
 /// 'raise from' to indicate that the chosen error was caused by the original error.
 inline void raise_from(PyObject *type, const char *message) {
     // Based on _PyErr_FormatVFromCause:
     // https://github.com/python/cpython/blob/467ab194fc6189d9f7310c89937c51abeac56839/Python/errors.c#L405
     // See https://github.com/pybind/pybind11/pull/2112 for details.
     PyObject *exc = nullptr, *val = nullptr, *val2 = nullptr, *tb = nullptr;
 
     assert(PyErr_Occurred());
     PyErr_Fetch(&exc, &val, &tb);
     PyErr_NormalizeException(&exc, &val, &tb);
     if (tb != nullptr) {
         PyException_SetTraceback(val, tb);
         Py_DECREF(tb);
     }
     Py_DECREF(exc);
     assert(!PyErr_Occurred());
 
     PyErr_SetString(type, message);
 
     PyErr_Fetch(&exc, &val2, &tb);
     PyErr_NormalizeException(&exc, &val2, &tb);
     Py_INCREF(val);
     PyException_SetCause(val2, val);
     PyException_SetContext(val2, val);
     PyErr_Restore(exc, val2, tb);
 }
 
 /// Sets the current Python error indicator with the chosen error, performing a 'raise from'
 /// from the error contained in error_already_set to indicate that the chosen error was
 /// caused by the original error. After this function is called error_already_set will
 /// no longer contain an error.
 inline void raise_from(error_already_set& err, PyObject *type, const char *message) {
     err.restore();
     raise_from(type, message);
 }
 
 #endif
 
 /** \defgroup python_builtins const_name
     Unless stated otherwise, the following C++ functions behave the same
     as their Python counterparts.
  */
 
 /** \ingroup python_builtins
     \rst
     Return true if ``obj`` is an instance of ``T``. Type ``T`` must be a subclass of
     `object` or a class which was exposed to Python as ``py::class_<T>``.
 \endrst */
 template <typename T, detail::enable_if_t<std::is_base_of<object, T>::value, int> = 0>
 bool isinstance(handle obj) { return T::check_(obj); }
 
 template <typename T, detail::enable_if_t<!std::is_base_of<object, T>::value, int> = 0>
 bool isinstance(handle obj) { return detail::isinstance_generic(obj, typeid(T)); }
 
 template <> inline bool isinstance<handle>(handle) = delete;
 template <> inline bool isinstance<object>(handle obj) { return obj.ptr() != nullptr; }
 
 /// \ingroup python_builtins
 /// Return true if ``obj`` is an instance of the ``type``.
 inline bool isinstance(handle obj, handle type) {
     const auto result = PyObject_IsInstance(obj.ptr(), type.ptr());
     if (result == -1)
         throw error_already_set();
     return result != 0;
 }
 
 /// \addtogroup python_builtins
 /// @{
 inline bool hasattr(handle obj, handle name) {
     return PyObject_HasAttr(obj.ptr(), name.ptr()) == 1;
 }
 
 inline bool hasattr(handle obj, const char *name) {
     return PyObject_HasAttrString(obj.ptr(), name) == 1;
 }
 
 inline void delattr(handle obj, handle name) {
     if (PyObject_DelAttr(obj.ptr(), name.ptr()) != 0) { throw error_already_set(); }
 }
 
 inline void delattr(handle obj, const char *name) {
     if (PyObject_DelAttrString(obj.ptr(), name) != 0) { throw error_already_set(); }
 }
 
 inline object getattr(handle obj, handle name) {
     PyObject *result = PyObject_GetAttr(obj.ptr(), name.ptr());
     if (!result) { throw error_already_set(); }
     return reinterpret_steal<object>(result);
 }
 
 inline object getattr(handle obj, const char *name) {
     PyObject *result = PyObject_GetAttrString(obj.ptr(), name);
     if (!result) { throw error_already_set(); }
     return reinterpret_steal<object>(result);
 }
 
 inline object getattr(handle obj, handle name, handle default_) {
     if (PyObject *result = PyObject_GetAttr(obj.ptr(), name.ptr())) {
         return reinterpret_steal<object>(result);
     }
     PyErr_Clear();
     return reinterpret_borrow<object>(default_);
 }
 
 inline object getattr(handle obj, const char *name, handle default_) {
     if (PyObject *result = PyObject_GetAttrString(obj.ptr(), name)) {
         return reinterpret_steal<object>(result);
     }
     PyErr_Clear();
     return reinterpret_borrow<object>(default_);
 }
 
 inline void setattr(handle obj, handle name, handle value) {
     if (PyObject_SetAttr(obj.ptr(), name.ptr(), value.ptr()) != 0) { throw error_already_set(); }
 }
 
 inline void setattr(handle obj, const char *name, handle value) {
     if (PyObject_SetAttrString(obj.ptr(), name, value.ptr()) != 0) { throw error_already_set(); }
 }
 
 inline ssize_t hash(handle obj) {
     auto h = PyObject_Hash(obj.ptr());
     if (h == -1) { throw error_already_set(); }
     return h;
 }
 
 /// @} python_builtins
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 inline handle get_function(handle value) {
     if (value) {
 #if PY_MAJOR_VERSION >= 3
         if (PyInstanceMethod_Check(value.ptr()))
             value = PyInstanceMethod_GET_FUNCTION(value.ptr());
         else
 #endif
         if (PyMethod_Check(value.ptr()))
             value = PyMethod_GET_FUNCTION(value.ptr());
     }
     return value;
 }
 
 // Reimplementation of python's dict helper functions to ensure that exceptions
 // aren't swallowed (see #2862)
 
 // copied from cpython _PyDict_GetItemStringWithError
 inline PyObject * dict_getitemstring(PyObject *v, const char *key)
 {
 #if PY_MAJOR_VERSION >= 3
     PyObject *kv = nullptr, *rv = nullptr;
     kv = PyUnicode_FromString(key);
     if (kv == NULL) {
         throw error_already_set();
     }
 
     rv = PyDict_GetItemWithError(v, kv);
     Py_DECREF(kv);
     if (rv == NULL && PyErr_Occurred()) {
         throw error_already_set();
     }
     return rv;
 #else
     return PyDict_GetItemString(v, key);
 #endif
 }
 
 inline PyObject * dict_getitem(PyObject *v, PyObject *key)
 {
 #if PY_MAJOR_VERSION >= 3
     PyObject *rv = PyDict_GetItemWithError(v, key);
     if (rv == NULL && PyErr_Occurred()) {
         throw error_already_set();
     }
     return rv;
 #else
     return PyDict_GetItem(v, key);
 #endif
 }
 
 // Helper aliases/functions to support implicit casting of values given to python accessors/methods.
 // When given a pyobject, this simply returns the pyobject as-is; for other C++ type, the value goes
 // through pybind11::cast(obj) to convert it to an `object`.
 template <typename T, enable_if_t<is_pyobject<T>::value, int> = 0>
 auto object_or_cast(T &&o) -> decltype(std::forward<T>(o)) { return std::forward<T>(o); }
 // The following casting version is implemented in cast.h:
 template <typename T, enable_if_t<!is_pyobject<T>::value, int> = 0>
 object object_or_cast(T &&o);
 // Match a PyObject*, which we want to convert directly to handle via its converting constructor
 inline handle object_or_cast(PyObject *ptr) { return ptr; }
 
 #if defined(_MSC_VER) && _MSC_VER < 1920
 #  pragma warning(push)
 #  pragma warning(disable: 4522) // warning C4522: multiple assignment operators specified
 #endif
 template <typename Policy>
 class accessor : public object_api<accessor<Policy>> {
     using key_type = typename Policy::key_type;
 
 public:
     accessor(handle obj, key_type key) : obj(obj), key(std::move(key)) { }
     accessor(const accessor &) = default;
     accessor(accessor &&) noexcept = default;
 
     // accessor overload required to override default assignment operator (templates are not allowed
     // to replace default compiler-generated assignments).
     void operator=(const accessor &a) && { std::move(*this).operator=(handle(a)); }
     void operator=(const accessor &a) & { operator=(handle(a)); }
 
     template <typename T> void operator=(T &&value) && {
         Policy::set(obj, key, object_or_cast(std::forward<T>(value)));
     }
     template <typename T> void operator=(T &&value) & {
         get_cache() = reinterpret_borrow<object>(object_or_cast(std::forward<T>(value)));
     }
 
     template <typename T = Policy>
     PYBIND11_DEPRECATED("Use of obj.attr(...) as bool is deprecated in favor of pybind11::hasattr(obj, ...)")
     explicit operator enable_if_t<std::is_same<T, accessor_policies::str_attr>::value ||
             std::is_same<T, accessor_policies::obj_attr>::value, bool>() const {
         return hasattr(obj, key);
     }
     template <typename T = Policy>
     PYBIND11_DEPRECATED("Use of obj[key] as bool is deprecated in favor of obj.contains(key)")
     explicit operator enable_if_t<std::is_same<T, accessor_policies::generic_item>::value, bool>() const {
         return obj.contains(key);
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator object() const { return get_cache(); }
     PyObject *ptr() const { return get_cache().ptr(); }
     template <typename T> T cast() const { return get_cache().template cast<T>(); }
 
 private:
     object &get_cache() const {
         if (!cache) { cache = Policy::get(obj, key); }
         return cache;
     }
 
 private:
     handle obj;
     key_type key;
     mutable object cache;
 };
 #if defined(_MSC_VER) && _MSC_VER < 1920
 #  pragma warning(pop)
 #endif
 
 PYBIND11_NAMESPACE_BEGIN(accessor_policies)
 struct obj_attr {
     using key_type = object;
     static object get(handle obj, handle key) { return getattr(obj, key); }
     static void set(handle obj, handle key, handle val) { setattr(obj, key, val); }
 };
 
 struct str_attr {
     using key_type = const char *;
     static object get(handle obj, const char *key) { return getattr(obj, key); }
     static void set(handle obj, const char *key, handle val) { setattr(obj, key, val); }
 };
 
 struct generic_item {
     using key_type = object;
 
     static object get(handle obj, handle key) {
         PyObject *result = PyObject_GetItem(obj.ptr(), key.ptr());
         if (!result) { throw error_already_set(); }
         return reinterpret_steal<object>(result);
     }
 
     static void set(handle obj, handle key, handle val) {
         if (PyObject_SetItem(obj.ptr(), key.ptr(), val.ptr()) != 0) { throw error_already_set(); }
     }
 };
 
 struct sequence_item {
     using key_type = size_t;
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static object get(handle obj, const IdxType &index) {
         PyObject *result = PySequence_GetItem(obj.ptr(), ssize_t_cast(index));
         if (!result) { throw error_already_set(); }
         return reinterpret_steal<object>(result);
     }
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static void set(handle obj, const IdxType &index, handle val) {
         // PySequence_SetItem does not steal a reference to 'val'
         if (PySequence_SetItem(obj.ptr(), ssize_t_cast(index), val.ptr()) != 0) {
             throw error_already_set();
         }
     }
 };
 
 struct list_item {
     using key_type = size_t;
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static object get(handle obj, const IdxType &index) {
         PyObject *result = PyList_GetItem(obj.ptr(), ssize_t_cast(index));
         if (!result) { throw error_already_set(); }
         return reinterpret_borrow<object>(result);
     }
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static void set(handle obj, const IdxType &index, handle val) {
         // PyList_SetItem steals a reference to 'val'
         if (PyList_SetItem(obj.ptr(), ssize_t_cast(index), val.inc_ref().ptr()) != 0) {
             throw error_already_set();
         }
     }
 };
 
 struct tuple_item {
     using key_type = size_t;
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static object get(handle obj, const IdxType &index) {
         PyObject *result = PyTuple_GetItem(obj.ptr(), ssize_t_cast(index));
         if (!result) { throw error_already_set(); }
         return reinterpret_borrow<object>(result);
     }
 
     template <typename IdxType, detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     static void set(handle obj, const IdxType &index, handle val) {
         // PyTuple_SetItem steals a reference to 'val'
         if (PyTuple_SetItem(obj.ptr(), ssize_t_cast(index), val.inc_ref().ptr()) != 0) {
             throw error_already_set();
         }
     }
 };
 PYBIND11_NAMESPACE_END(accessor_policies)
 
 /// STL iterator template used for tuple, list, sequence and dict
 template <typename Policy>
 class generic_iterator : public Policy {
     using It = generic_iterator;
 
 public:
     using difference_type = ssize_t;
     using iterator_category = typename Policy::iterator_category;
     using value_type = typename Policy::value_type;
     using reference = typename Policy::reference;
     using pointer = typename Policy::pointer;
 
     generic_iterator() = default;
     generic_iterator(handle seq, ssize_t index) : Policy(seq, index) { }
 
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference operator*() const { return Policy::dereference(); }
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference operator[](difference_type n) const { return *(*this + n); }
     pointer operator->() const { return **this; }
 
     It &operator++() { Policy::increment(); return *this; }
     It operator++(int) { auto copy = *this; Policy::increment(); return copy; }
     It &operator--() { Policy::decrement(); return *this; }
     It operator--(int) { auto copy = *this; Policy::decrement(); return copy; }
     It &operator+=(difference_type n) { Policy::advance(n); return *this; }
     It &operator-=(difference_type n) { Policy::advance(-n); return *this; }
 
     friend It operator+(const It &a, difference_type n) { auto copy = a; return copy += n; }
     friend It operator+(difference_type n, const It &b) { return b + n; }
     friend It operator-(const It &a, difference_type n) { auto copy = a; return copy -= n; }
     friend difference_type operator-(const It &a, const It &b) { return a.distance_to(b); }
 
     friend bool operator==(const It &a, const It &b) { return a.equal(b); }
     friend bool operator!=(const It &a, const It &b) { return !(a == b); }
     friend bool operator< (const It &a, const It &b) { return b - a > 0; }
     friend bool operator> (const It &a, const It &b) { return b < a; }
     friend bool operator>=(const It &a, const It &b) { return !(a < b); }
     friend bool operator<=(const It &a, const It &b) { return !(a > b); }
 };
 
 PYBIND11_NAMESPACE_BEGIN(iterator_policies)
 /// Quick proxy class needed to implement ``operator->`` for iterators which can't return pointers
 template <typename T>
 struct arrow_proxy {
     T value;
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     arrow_proxy(T &&value) noexcept : value(std::move(value)) { }
     T *operator->() const { return &value; }
 };
 
 /// Lightweight iterator policy using just a simple pointer: see ``PySequence_Fast_ITEMS``
 class sequence_fast_readonly {
 protected:
     using iterator_category = std::random_access_iterator_tag;
     using value_type = handle;
     using reference = const handle; // PR #3263
     using pointer = arrow_proxy<const handle>;
 
     sequence_fast_readonly(handle obj, ssize_t n) : ptr(PySequence_Fast_ITEMS(obj.ptr()) + n) { }
 
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference dereference() const { return *ptr; }
     void increment() { ++ptr; }
     void decrement() { --ptr; }
     void advance(ssize_t n) { ptr += n; }
     bool equal(const sequence_fast_readonly &b) const { return ptr == b.ptr; }
     ssize_t distance_to(const sequence_fast_readonly &b) const { return ptr - b.ptr; }
 
 private:
     PyObject **ptr;
 };
 
 /// Full read and write access using the sequence protocol: see ``detail::sequence_accessor``
 class sequence_slow_readwrite {
 protected:
     using iterator_category = std::random_access_iterator_tag;
     using value_type = object;
     using reference = sequence_accessor;
     using pointer = arrow_proxy<const sequence_accessor>;
 
     sequence_slow_readwrite(handle obj, ssize_t index) : obj(obj), index(index) { }
 
     reference dereference() const { return {obj, static_cast<size_t>(index)}; }
     void increment() { ++index; }
     void decrement() { --index; }
     void advance(ssize_t n) { index += n; }
     bool equal(const sequence_slow_readwrite &b) const { return index == b.index; }
     ssize_t distance_to(const sequence_slow_readwrite &b) const { return index - b.index; }
 
 private:
     handle obj;
     ssize_t index;
 };
 
 /// Python's dictionary protocol permits this to be a forward iterator
 class dict_readonly {
 protected:
     using iterator_category = std::forward_iterator_tag;
     using value_type = std::pair<handle, handle>;
     using reference = const value_type; // PR #3263
     using pointer = arrow_proxy<const value_type>;
 
     dict_readonly() = default;
     dict_readonly(handle obj, ssize_t pos) : obj(obj), pos(pos) { increment(); }
 
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference dereference() const { return {key, value}; }
     void increment() {
         if (PyDict_Next(obj.ptr(), &pos, &key, &value) == 0) {
             pos = -1;
         }
     }
     bool equal(const dict_readonly &b) const { return pos == b.pos; }
 
 private:
     handle obj;
     PyObject *key = nullptr, *value = nullptr;
     ssize_t pos = -1;
 };
 PYBIND11_NAMESPACE_END(iterator_policies)
 
 #if !defined(PYPY_VERSION)
 using tuple_iterator = generic_iterator<iterator_policies::sequence_fast_readonly>;
 using list_iterator = generic_iterator<iterator_policies::sequence_fast_readonly>;
 #else
 using tuple_iterator = generic_iterator<iterator_policies::sequence_slow_readwrite>;
 using list_iterator = generic_iterator<iterator_policies::sequence_slow_readwrite>;
 #endif
 
 using sequence_iterator = generic_iterator<iterator_policies::sequence_slow_readwrite>;
 using dict_iterator = generic_iterator<iterator_policies::dict_readonly>;
 
 inline bool PyIterable_Check(PyObject *obj) {
     PyObject *iter = PyObject_GetIter(obj);
     if (iter) {
         Py_DECREF(iter);
         return true;
     }
     PyErr_Clear();
     return false;
 }
 
 inline bool PyNone_Check(PyObject *o) { return o == Py_None; }
 inline bool PyEllipsis_Check(PyObject *o) { return o == Py_Ellipsis; }
 
 #ifdef PYBIND11_STR_LEGACY_PERMISSIVE
 inline bool PyUnicode_Check_Permissive(PyObject *o) { return PyUnicode_Check(o) || PYBIND11_BYTES_CHECK(o); }
 #define PYBIND11_STR_CHECK_FUN detail::PyUnicode_Check_Permissive
 #else
 #define PYBIND11_STR_CHECK_FUN PyUnicode_Check
 #endif
 
 inline bool PyStaticMethod_Check(PyObject *o) { return o->ob_type == &PyStaticMethod_Type; }
 
 class kwargs_proxy : public handle {
 public:
     explicit kwargs_proxy(handle h) : handle(h) { }
 };
 
 class args_proxy : public handle {
 public:
     explicit args_proxy(handle h) : handle(h) { }
     kwargs_proxy operator*() const { return kwargs_proxy(*this); }
 };
 
 /// Python argument categories (using PEP 448 terms)
 template <typename T> using is_keyword = std::is_base_of<arg, T>;
 template <typename T> using is_s_unpacking = std::is_same<args_proxy, T>; // * unpacking
 template <typename T> using is_ds_unpacking = std::is_same<kwargs_proxy, T>; // ** unpacking
 template <typename T> using is_positional = satisfies_none_of<T,
     is_keyword, is_s_unpacking, is_ds_unpacking
 >;
 template <typename T> using is_keyword_or_ds = satisfies_any_of<T, is_keyword, is_ds_unpacking>;
 
 // Call argument collector forward declarations
 template <return_value_policy policy = return_value_policy::automatic_reference>
 class simple_collector;
 template <return_value_policy policy = return_value_policy::automatic_reference>
 class unpacking_collector;
 
 PYBIND11_NAMESPACE_END(detail)
 
 // TODO: After the deprecated constructors are removed, this macro can be simplified by
 //       inheriting ctors: `using Parent::Parent`. It's not an option right now because
 //       the `using` statement triggers the parent deprecation warning even if the ctor
 //       isn't even used.
 #define PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     public: \
         PYBIND11_DEPRECATED("Use reinterpret_borrow<"#Name">() or reinterpret_steal<"#Name">()") \
         Name(handle h, bool is_borrowed) : Parent(is_borrowed ? Parent(h, borrowed_t{}) : Parent(h, stolen_t{})) { } \
         Name(handle h, borrowed_t) : Parent(h, borrowed_t{}) { } \
         Name(handle h, stolen_t) : Parent(h, stolen_t{}) { } \
         PYBIND11_DEPRECATED("Use py::isinstance<py::python_type>(obj) instead") \
         bool check() const { return m_ptr != nullptr && (CheckFun(m_ptr) != 0); } \
         static bool check_(handle h) { return h.ptr() != nullptr && CheckFun(h.ptr()); } \
         template <typename Policy_> \
         /* NOLINTNEXTLINE(google-explicit-constructor) */ \
         Name(const ::pybind11::detail::accessor<Policy_> &a) : Name(object(a)) { }
 
 #define PYBIND11_OBJECT_CVT(Name, Parent, CheckFun, ConvertFun) \
     PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     /* This is deliberately not 'explicit' to allow implicit conversion from object: */ \
     /* NOLINTNEXTLINE(google-explicit-constructor) */ \
     Name(const object &o) \
     : Parent(check_(o) ? o.inc_ref().ptr() : ConvertFun(o.ptr()), stolen_t{}) \
     { if (!m_ptr) throw error_already_set(); } \
     /* NOLINTNEXTLINE(google-explicit-constructor) */ \
     Name(object &&o) \
     : Parent(check_(o) ? o.release().ptr() : ConvertFun(o.ptr()), stolen_t{}) \
     { if (!m_ptr) throw error_already_set(); }
 
 #define PYBIND11_OBJECT_CVT_DEFAULT(Name, Parent, CheckFun, ConvertFun) \
     PYBIND11_OBJECT_CVT(Name, Parent, CheckFun, ConvertFun) \
     Name() : Parent() { }
 
 #define PYBIND11_OBJECT_CHECK_FAILED(Name, o_ptr) \
     ::pybind11::type_error("Object of type '" + \
                            ::pybind11::detail::get_fully_qualified_tp_name(Py_TYPE(o_ptr)) + \
                            "' is not an instance of '" #Name "'")
 
 #define PYBIND11_OBJECT(Name, Parent, CheckFun) \
     PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     /* This is deliberately not 'explicit' to allow implicit conversion from object: */ \
     /* NOLINTNEXTLINE(google-explicit-constructor) */ \
     Name(const object &o) : Parent(o) \
     { if (m_ptr && !check_(m_ptr)) throw PYBIND11_OBJECT_CHECK_FAILED(Name, m_ptr); } \
     /* NOLINTNEXTLINE(google-explicit-constructor) */ \
     Name(object &&o) : Parent(std::move(o)) \
     { if (m_ptr && !check_(m_ptr)) throw PYBIND11_OBJECT_CHECK_FAILED(Name, m_ptr); }
 
 #define PYBIND11_OBJECT_DEFAULT(Name, Parent, CheckFun) \
     PYBIND11_OBJECT(Name, Parent, CheckFun) \
     Name() : Parent() { }
 
 /// \addtogroup pytypes
 /// @{
 
 /** \rst
     Wraps a Python iterator so that it can also be used as a C++ input iterator
 
     Caveat: copying an iterator does not (and cannot) clone the internal
     state of the Python iterable. This also applies to the post-increment
     operator. This iterator should only be used to retrieve the current
     value using ``operator*()``.
 \endrst */
 class iterator : public object {
 public:
     using iterator_category = std::input_iterator_tag;
     using difference_type = ssize_t;
     using value_type = handle;
     using reference = const handle; // PR #3263
     using pointer = const handle *;
 
     PYBIND11_OBJECT_DEFAULT(iterator, object, PyIter_Check)
 
     iterator& operator++() {
         advance();
         return *this;
     }
 
     iterator operator++(int) {
         auto rv = *this;
         advance();
         return rv;
     }
 
     // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
     reference operator*() const {
         if (m_ptr && !value.ptr()) {
             auto& self = const_cast<iterator &>(*this);
             self.advance();
         }
         return value;
     }
 
     pointer operator->() const { operator*(); return &value; }
 
     /** \rst
          The value which marks the end of the iteration. ``it == iterator::sentinel()``
          is equivalent to catching ``StopIteration`` in Python.
 
          .. code-block:: cpp
 
              void foo(py::iterator it) {
                  while (it != py::iterator::sentinel()) {
                     // use `*it`
                     ++it;
                  }
              }
     \endrst */
     static iterator sentinel() { return {}; }
 
     friend bool operator==(const iterator &a, const iterator &b) { return a->ptr() == b->ptr(); }
     friend bool operator!=(const iterator &a, const iterator &b) { return a->ptr() != b->ptr(); }
 
 private:
     void advance() {
         value = reinterpret_steal<object>(PyIter_Next(m_ptr));
         if (PyErr_Occurred()) { throw error_already_set(); }
     }
 
 private:
     object value = {};
 };
 
 
 
 class type : public object {
 public:
     PYBIND11_OBJECT(type, object, PyType_Check)
 
     /// Return a type handle from a handle or an object
     static handle handle_of(handle h) { return handle((PyObject*) Py_TYPE(h.ptr())); }
 
     /// Return a type object from a handle or an object
     static type of(handle h) { return type(type::handle_of(h), borrowed_t{}); }
 
     // Defined in pybind11/cast.h
     /// Convert C++ type to handle if previously registered. Does not convert
     /// standard types, like int, float. etc. yet.
     /// See https://github.com/pybind/pybind11/issues/2486
     template<typename T>
     static handle handle_of();
 
     /// Convert C++ type to type if previously registered. Does not convert
     /// standard types, like int, float. etc. yet.
     /// See https://github.com/pybind/pybind11/issues/2486
     template<typename T>
     static type of() {return type(type::handle_of<T>(), borrowed_t{}); }
 };
 
 class iterable : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(iterable, object, detail::PyIterable_Check)
 };
 
 class bytes;
 
 class str : public object {
 public:
     PYBIND11_OBJECT_CVT(str, object, PYBIND11_STR_CHECK_FUN, raw_str)
 
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     str(const char *c, const SzType &n)
         : object(PyUnicode_FromStringAndSize(c, ssize_t_cast(n)), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate string object!");
     }
 
     // 'explicit' is explicitly omitted from the following constructors to allow implicit conversion to py::str from C++ string-like objects
     // NOLINTNEXTLINE(google-explicit-constructor)
     str(const char *c = "")
         : object(PyUnicode_FromString(c), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate string object!");
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     str(const std::string &s) : str(s.data(), s.size()) { }
 
 #ifdef PYBIND11_HAS_STRING_VIEW
     // enable_if is needed to avoid "ambiguous conversion" errors (see PR #3521).
     template <typename T, detail::enable_if_t<std::is_same<T, std::string_view>::value, int> = 0>
     // NOLINTNEXTLINE(google-explicit-constructor)
     str(T s) : str(s.data(), s.size()) { }
 
 # ifdef PYBIND11_HAS_U8STRING
     // reinterpret_cast here is safe (C++20 guarantees char8_t has the same size/alignment as char)
     // NOLINTNEXTLINE(google-explicit-constructor)
     str(std::u8string_view s) : str(reinterpret_cast<const char*>(s.data()), s.size()) { }
 # endif
 
 #endif
 
     explicit str(const bytes &b);
 
     /** \rst
         Return a string representation of the object. This is analogous to
         the ``str()`` function in Python.
     \endrst */
     explicit str(handle h) : object(raw_str(h.ptr()), stolen_t{}) { if (!m_ptr) throw error_already_set(); }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator std::string() const {
         object temp = *this;
         if (PyUnicode_Check(m_ptr)) {
             temp = reinterpret_steal<object>(PyUnicode_AsUTF8String(m_ptr));
             if (!temp)
                 throw error_already_set();
         }
         char *buffer = nullptr;
         ssize_t length = 0;
         if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length))
             pybind11_fail("Unable to extract string contents! (invalid type)");
         return std::string(buffer, (size_t) length);
     }
 
     template <typename... Args>
     str format(Args &&...args) const {
         return attr("format")(std::forward<Args>(args)...);
     }
 
 private:
     /// Return string representation -- always returns a new reference, even if already a str
     static PyObject *raw_str(PyObject *op) {
         PyObject *str_value = PyObject_Str(op);
 #if PY_MAJOR_VERSION < 3
         if (!str_value) throw error_already_set();
         PyObject *unicode = PyUnicode_FromEncodedObject(str_value, "utf-8", nullptr);
         Py_XDECREF(str_value); str_value = unicode;
 #endif
         return str_value;
     }
 };
 /// @} pytypes
 
 inline namespace literals {
 /** \rst
     String literal version of `str`
  \endrst */
 inline str operator"" _s(const char *s, size_t size) { return {s, size}; }
 } // namespace literals
 
 /// \addtogroup pytypes
 /// @{
 class bytes : public object {
 public:
     PYBIND11_OBJECT(bytes, object, PYBIND11_BYTES_CHECK)
 
     // Allow implicit conversion:
     // NOLINTNEXTLINE(google-explicit-constructor)
     bytes(const char *c = "")
         : object(PYBIND11_BYTES_FROM_STRING(c), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
     }
 
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     bytes(const char *c, const SzType &n)
         : object(PYBIND11_BYTES_FROM_STRING_AND_SIZE(c, ssize_t_cast(n)), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
     }
 
     // Allow implicit conversion:
     // NOLINTNEXTLINE(google-explicit-constructor)
     bytes(const std::string &s) : bytes(s.data(), s.size()) { }
 
     explicit bytes(const pybind11::str &s);
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator std::string() const {
         char *buffer = nullptr;
         ssize_t length = 0;
         if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length))
             pybind11_fail("Unable to extract bytes contents!");
         return std::string(buffer, (size_t) length);
     }
 
 #ifdef PYBIND11_HAS_STRING_VIEW
     // enable_if is needed to avoid "ambiguous conversion" errors (see PR #3521).
     template <typename T, detail::enable_if_t<std::is_same<T, std::string_view>::value, int> = 0>
     // NOLINTNEXTLINE(google-explicit-constructor)
     bytes(T s) : bytes(s.data(), s.size()) { }
 
     // Obtain a string view that views the current `bytes` buffer value.  Note that this is only
     // valid so long as the `bytes` instance remains alive and so generally should not outlive the
     // lifetime of the `bytes` instance.
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator std::string_view() const {
         char *buffer = nullptr;
         ssize_t length = 0;
         if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length))
             pybind11_fail("Unable to extract bytes contents!");
         return {buffer, static_cast<size_t>(length)};
     }
 #endif
 
 };
 // Note: breathe >= 4.17.0 will fail to build docs if the below two constructors
 // are included in the doxygen group; close here and reopen after as a workaround
 /// @} pytypes
 
 inline bytes::bytes(const pybind11::str &s) {
     object temp = s;
     if (PyUnicode_Check(s.ptr())) {
         temp = reinterpret_steal<object>(PyUnicode_AsUTF8String(s.ptr()));
         if (!temp)
             pybind11_fail("Unable to extract string contents! (encoding issue)");
     }
     char *buffer = nullptr;
     ssize_t length = 0;
     if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length))
         pybind11_fail("Unable to extract string contents! (invalid type)");
     auto obj = reinterpret_steal<object>(PYBIND11_BYTES_FROM_STRING_AND_SIZE(buffer, length));
     if (!obj)
         pybind11_fail("Could not allocate bytes object!");
     m_ptr = obj.release().ptr();
 }
 
 inline str::str(const bytes& b) {
     char *buffer = nullptr;
     ssize_t length = 0;
     if (PYBIND11_BYTES_AS_STRING_AND_SIZE(b.ptr(), &buffer, &length))
         pybind11_fail("Unable to extract bytes contents!");
     auto obj = reinterpret_steal<object>(PyUnicode_FromStringAndSize(buffer, length));
     if (!obj)
         pybind11_fail("Could not allocate string object!");
     m_ptr = obj.release().ptr();
 }
 
 /// \addtogroup pytypes
 /// @{
 class bytearray : public object {
 public:
     PYBIND11_OBJECT_CVT(bytearray, object, PyByteArray_Check, PyByteArray_FromObject)
 
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     bytearray(const char *c, const SzType &n)
         : object(PyByteArray_FromStringAndSize(c, ssize_t_cast(n)), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate bytearray object!");
     }
 
     bytearray()
         : bytearray("", 0) {}
 
     explicit bytearray(const std::string &s) : bytearray(s.data(), s.size()) { }
 
     size_t size() const { return static_cast<size_t>(PyByteArray_Size(m_ptr)); }
 
     explicit operator std::string() const {
         char *buffer = PyByteArray_AS_STRING(m_ptr);
         ssize_t size = PyByteArray_GET_SIZE(m_ptr);
         return std::string(buffer, static_cast<size_t>(size));
     }
 };
 // Note: breathe >= 4.17.0 will fail to build docs if the below two constructors
 // are included in the doxygen group; close here and reopen after as a workaround
 /// @} pytypes
 
 /// \addtogroup pytypes
 /// @{
 class none : public object {
 public:
     PYBIND11_OBJECT(none, object, detail::PyNone_Check)
     none() : object(Py_None, borrowed_t{}) { }
 };
 
 class ellipsis : public object {
 public:
     PYBIND11_OBJECT(ellipsis, object, detail::PyEllipsis_Check)
     ellipsis() : object(Py_Ellipsis, borrowed_t{}) { }
 };
 
 class bool_ : public object {
 public:
     PYBIND11_OBJECT_CVT(bool_, object, PyBool_Check, raw_bool)
     bool_() : object(Py_False, borrowed_t{}) { }
     // Allow implicit conversion from and to `bool`:
     // NOLINTNEXTLINE(google-explicit-constructor)
     bool_(bool value) : object(value ? Py_True : Py_False, borrowed_t{}) { }
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator bool() const { return (m_ptr != nullptr) && PyLong_AsLong(m_ptr) != 0; }
 
 private:
     /// Return the truth value of an object -- always returns a new reference
     static PyObject *raw_bool(PyObject *op) {
         const auto value = PyObject_IsTrue(op);
         if (value == -1) return nullptr;
         return handle(value != 0 ? Py_True : Py_False).inc_ref().ptr();
     }
 };
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 // Converts a value to the given unsigned type.  If an error occurs, you get back (Unsigned) -1;
 // otherwise you get back the unsigned long or unsigned long long value cast to (Unsigned).
 // (The distinction is critically important when casting a returned -1 error value to some other
 // unsigned type: (A)-1 != (B)-1 when A and B are unsigned types of different sizes).
 template <typename Unsigned>
 Unsigned as_unsigned(PyObject *o) {
     if (PYBIND11_SILENCE_MSVC_C4127(sizeof(Unsigned) <= sizeof(unsigned long))
 #if PY_VERSION_HEX < 0x03000000
         || PyInt_Check(o)
 #endif
     ) {
         unsigned long v = PyLong_AsUnsignedLong(o);
         return v == (unsigned long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
     }
     unsigned long long v = PyLong_AsUnsignedLongLong(o);
     return v == (unsigned long long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
 }
 PYBIND11_NAMESPACE_END(detail)
 
 class int_ : public object {
 public:
     PYBIND11_OBJECT_CVT(int_, object, PYBIND11_LONG_CHECK, PyNumber_Long)
     int_() : object(PyLong_FromLong(0), stolen_t{}) { }
     // Allow implicit conversion from C++ integral types:
     template <typename T,
               detail::enable_if_t<std::is_integral<T>::value, int> = 0>
     // NOLINTNEXTLINE(google-explicit-constructor)
     int_(T value) {
         if (PYBIND11_SILENCE_MSVC_C4127(sizeof(T) <= sizeof(long))) {
             if (std::is_signed<T>::value)
                 m_ptr = PyLong_FromLong((long) value);
             else
                 m_ptr = PyLong_FromUnsignedLong((unsigned long) value);
         } else {
             if (std::is_signed<T>::value)
                 m_ptr = PyLong_FromLongLong((long long) value);
             else
                 m_ptr = PyLong_FromUnsignedLongLong((unsigned long long) value);
         }
         if (!m_ptr) pybind11_fail("Could not allocate int object!");
     }
 
     template <typename T,
               detail::enable_if_t<std::is_integral<T>::value, int> = 0>
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator T() const {
         return std::is_unsigned<T>::value
             ? detail::as_unsigned<T>(m_ptr)
             : sizeof(T) <= sizeof(long)
               ? (T) PyLong_AsLong(m_ptr)
               : (T) PYBIND11_LONG_AS_LONGLONG(m_ptr);
     }
 };
 
 class float_ : public object {
 public:
     PYBIND11_OBJECT_CVT(float_, object, PyFloat_Check, PyNumber_Float)
     // Allow implicit conversion from float/double:
     // NOLINTNEXTLINE(google-explicit-constructor)
     float_(float value) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate float object!");
     }
     // NOLINTNEXTLINE(google-explicit-constructor)
     float_(double value = .0) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate float object!");
     }
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator float() const { return (float) PyFloat_AsDouble(m_ptr); }
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator double() const { return (double) PyFloat_AsDouble(m_ptr); }
 };
 
 class weakref : public object {
 public:
     PYBIND11_OBJECT_CVT_DEFAULT(weakref, object, PyWeakref_Check, raw_weakref)
     explicit weakref(handle obj, handle callback = {})
         : object(PyWeakref_NewRef(obj.ptr(), callback.ptr()), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate weak reference!");
     }
 
 private:
     static PyObject *raw_weakref(PyObject *o) {
         return PyWeakref_NewRef(o, nullptr);
     }
 };
 
 class slice : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(slice, object, PySlice_Check)
     slice(handle start, handle stop, handle step) {
         m_ptr = PySlice_New(start.ptr(), stop.ptr(), step.ptr());
         if (!m_ptr)
             pybind11_fail("Could not allocate slice object!");
     }
 
 #ifdef PYBIND11_HAS_OPTIONAL
     slice(std::optional<ssize_t> start, std::optional<ssize_t> stop, std::optional<ssize_t> step)
         : slice(index_to_object(start), index_to_object(stop), index_to_object(step)) {}
 #else
     slice(ssize_t start_, ssize_t stop_, ssize_t step_)
         : slice(int_(start_), int_(stop_), int_(step_)) {}
 #endif
 
     bool compute(size_t length, size_t *start, size_t *stop, size_t *step,
                  size_t *slicelength) const {
         return PySlice_GetIndicesEx((PYBIND11_SLICE_OBJECT *) m_ptr,
                                     (ssize_t) length, (ssize_t *) start,
                                     (ssize_t *) stop, (ssize_t *) step,
                                     (ssize_t *) slicelength) == 0;
     }
     bool compute(ssize_t length, ssize_t *start, ssize_t *stop, ssize_t *step,
       ssize_t *slicelength) const {
       return PySlice_GetIndicesEx((PYBIND11_SLICE_OBJECT *) m_ptr,
           length, start,
           stop, step,
           slicelength) == 0;
     }
 
 private:
     template <typename T>
     static object index_to_object(T index) {
         return index ? object(int_(*index)) : object(none());
     }
 };
 
 class capsule : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(capsule, object, PyCapsule_CheckExact)
     PYBIND11_DEPRECATED("Use reinterpret_borrow<capsule>() or reinterpret_steal<capsule>()")
     capsule(PyObject *ptr, bool is_borrowed) : object(is_borrowed ? object(ptr, borrowed_t{}) : object(ptr, stolen_t{})) { }
 
     explicit capsule(const void *value, const char *name = nullptr, void (*destructor)(PyObject *) = nullptr)
         : object(PyCapsule_New(const_cast<void *>(value), name, destructor), stolen_t{}) {
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
     }
 
     PYBIND11_DEPRECATED("Please pass a destructor that takes a void pointer as input")
     capsule(const void *value, void (*destruct)(PyObject *))
         : object(PyCapsule_New(const_cast<void*>(value), nullptr, destruct), stolen_t{}) {
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
     }
 
     capsule(const void *value, void (*destructor)(void *)) {
         m_ptr = PyCapsule_New(const_cast<void *>(value), nullptr, [](PyObject *o) {
             auto destructor = reinterpret_cast<void (*)(void *)>(PyCapsule_GetContext(o));
             void *ptr = PyCapsule_GetPointer(o, nullptr);
             destructor(ptr);
         });
 
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
 
         if (PyCapsule_SetContext(m_ptr, (void *) destructor) != 0)
             pybind11_fail("Could not set capsule context!");
     }
 
     explicit capsule(void (*destructor)()) {
         m_ptr = PyCapsule_New(reinterpret_cast<void *>(destructor), nullptr, [](PyObject *o) {
             auto destructor = reinterpret_cast<void (*)()>(PyCapsule_GetPointer(o, nullptr));
             destructor();
         });
 
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     template <typename T> operator T *() const {
         return get_pointer<T>();
     }
 
     /// Get the pointer the capsule holds.
     template<typename T = void>
     T* get_pointer() const {
         auto name = this->name();
         T *result = static_cast<T *>(PyCapsule_GetPointer(m_ptr, name));
         if (!result) {
             PyErr_Clear();
             pybind11_fail("Unable to extract capsule contents!");
         }
         return result;
     }
 
     /// Replaces a capsule's pointer *without* calling the destructor on the existing one.
     void set_pointer(const void *value) {
         if (PyCapsule_SetPointer(m_ptr, const_cast<void *>(value)) != 0) {
             PyErr_Clear();
             pybind11_fail("Could not set capsule pointer");
         }
     }
 
     const char *name() const { return PyCapsule_GetName(m_ptr); }
 };
 
 class tuple : public object {
 public:
     PYBIND11_OBJECT_CVT(tuple, object, PyTuple_Check, PySequence_Tuple)
     template <typename SzType = ssize_t,
               detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     // Some compilers generate link errors when using `const SzType &` here:
     explicit tuple(SzType size = 0) : object(PyTuple_New(ssize_t_cast(size)), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate tuple object!");
     }
     size_t size() const { return (size_t) PyTuple_Size(m_ptr); }
     bool empty() const { return size() == 0; }
     detail::tuple_accessor operator[](size_t index) const { return {*this, index}; }
     detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::tuple_iterator begin() const { return {*this, 0}; }
     detail::tuple_iterator end() const { return {*this, PyTuple_GET_SIZE(m_ptr)}; }
 };
 
 // We need to put this into a separate function because the Intel compiler
 // fails to compile enable_if_t<all_of<is_keyword_or_ds<Args>...>::value> part below
 // (tested with ICC 2021.1 Beta 20200827).
 template <typename... Args>
 constexpr bool args_are_all_keyword_or_ds()
 {
   return detail::all_of<detail::is_keyword_or_ds<Args>...>::value;
 }
 
 class dict : public object {
 public:
     PYBIND11_OBJECT_CVT(dict, object, PyDict_Check, raw_dict)
     dict() : object(PyDict_New(), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate dict object!");
     }
     template <typename... Args,
               typename = detail::enable_if_t<args_are_all_keyword_or_ds<Args...>()>,
               // MSVC workaround: it can't compile an out-of-line definition, so defer the collector
               typename collector = detail::deferred_t<detail::unpacking_collector<>, Args...>>
     explicit dict(Args &&...args) : dict(collector(std::forward<Args>(args)...).kwargs()) { }
 
     size_t size() const { return (size_t) PyDict_Size(m_ptr); }
     bool empty() const { return size() == 0; }
     detail::dict_iterator begin() const { return {*this, 0}; }
     detail::dict_iterator end() const { return {}; }
     void clear() /* py-non-const */ { PyDict_Clear(ptr()); }
     template <typename T> bool contains(T &&key) const {
         return PyDict_Contains(m_ptr, detail::object_or_cast(std::forward<T>(key)).ptr()) == 1;
     }
 
 private:
     /// Call the `dict` Python type -- always returns a new reference
     static PyObject *raw_dict(PyObject *op) {
         if (PyDict_Check(op))
             return handle(op).inc_ref().ptr();
         return PyObject_CallFunctionObjArgs((PyObject *) &PyDict_Type, op, nullptr);
     }
 };
 
 class sequence : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(sequence, object, PySequence_Check)
     size_t size() const {
         ssize_t result = PySequence_Size(m_ptr);
         if (result == -1)
             throw error_already_set();
         return (size_t) result;
     }
     bool empty() const { return size() == 0; }
     detail::sequence_accessor operator[](size_t index) const { return {*this, index}; }
     detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::sequence_iterator begin() const { return {*this, 0}; }
     detail::sequence_iterator end() const { return {*this, PySequence_Size(m_ptr)}; }
 };
 
 class list : public object {
 public:
     PYBIND11_OBJECT_CVT(list, object, PyList_Check, PySequence_List)
     template <typename SzType = ssize_t,
               detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     // Some compilers generate link errors when using `const SzType &` here:
     explicit list(SzType size = 0) : object(PyList_New(ssize_t_cast(size)), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate list object!");
     }
     size_t size() const { return (size_t) PyList_Size(m_ptr); }
     bool empty() const { return size() == 0; }
     detail::list_accessor operator[](size_t index) const { return {*this, index}; }
     detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::list_iterator begin() const { return {*this, 0}; }
     detail::list_iterator end() const { return {*this, PyList_GET_SIZE(m_ptr)}; }
     template <typename T> void append(T &&val) /* py-non-const */ {
         PyList_Append(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr());
     }
     template <typename IdxType,
               typename ValType,
               detail::enable_if_t<std::is_integral<IdxType>::value, int> = 0>
     void insert(const IdxType &index, ValType &&val) /* py-non-const */ {
         PyList_Insert(
             m_ptr, ssize_t_cast(index), detail::object_or_cast(std::forward<ValType>(val)).ptr());
     }
 };
 
 class args : public tuple { PYBIND11_OBJECT_DEFAULT(args, tuple, PyTuple_Check) };
 class kwargs : public dict { PYBIND11_OBJECT_DEFAULT(kwargs, dict, PyDict_Check)  };
 
 class set : public object {
 public:
     PYBIND11_OBJECT_CVT(set, object, PySet_Check, PySet_New)
     set() : object(PySet_New(nullptr), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate set object!");
     }
     size_t size() const { return (size_t) PySet_Size(m_ptr); }
     bool empty() const { return size() == 0; }
     template <typename T> bool add(T &&val) /* py-non-const */ {
         return PySet_Add(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr()) == 0;
     }
     void clear() /* py-non-const */ { PySet_Clear(m_ptr); }
     template <typename T> bool contains(T &&val) const {
         return PySet_Contains(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr()) == 1;
     }
 };
 
 class function : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(function, object, PyCallable_Check)
     handle cpp_function() const {
         handle fun = detail::get_function(m_ptr);
         if (fun && PyCFunction_Check(fun.ptr()))
             return fun;
         return handle();
     }
     bool is_cpp_function() const { return (bool) cpp_function(); }
 };
 
 class staticmethod : public object {
 public:
     PYBIND11_OBJECT_CVT(staticmethod, object, detail::PyStaticMethod_Check, PyStaticMethod_New)
 };
 
 class buffer : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(buffer, object, PyObject_CheckBuffer)
 
     buffer_info request(bool writable = false) const {
         int flags = PyBUF_STRIDES | PyBUF_FORMAT;
         if (writable) flags |= PyBUF_WRITABLE;
         auto *view = new Py_buffer();
         if (PyObject_GetBuffer(m_ptr, view, flags) != 0) {
             delete view;
             throw error_already_set();
         }
         return buffer_info(view);
     }
 };
 
 class memoryview : public object {
 public:
     PYBIND11_OBJECT_CVT(memoryview, object, PyMemoryView_Check, PyMemoryView_FromObject)
 
     /** \rst
         Creates ``memoryview`` from ``buffer_info``.
 
         ``buffer_info`` must be created from ``buffer::request()``. Otherwise
         throws an exception.
 
         For creating a ``memoryview`` from objects that support buffer protocol,
         use ``memoryview(const object& obj)`` instead of this constructor.
      \endrst */
     explicit memoryview(const buffer_info& info) {
         if (!info.view())
             pybind11_fail("Prohibited to create memoryview without Py_buffer");
         // Note: PyMemoryView_FromBuffer never increments obj reference.
         m_ptr = (info.view()->obj) ?
             PyMemoryView_FromObject(info.view()->obj) :
             PyMemoryView_FromBuffer(info.view());
         if (!m_ptr)
             pybind11_fail("Unable to create memoryview from buffer descriptor");
     }
 
     /** \rst
         Creates ``memoryview`` from static buffer.
 
         This method is meant for providing a ``memoryview`` for C/C++ buffer not
         managed by Python. The caller is responsible for managing the lifetime
         of ``ptr`` and ``format``, which MUST outlive the memoryview constructed
         here.
 
         See also: Python C API documentation for `PyMemoryView_FromBuffer`_.
 
         .. _PyMemoryView_FromBuffer: https://docs.python.org/c-api/memoryview.html#c.PyMemoryView_FromBuffer
 
         :param ptr: Pointer to the buffer.
         :param itemsize: Byte size of an element.
         :param format: Pointer to the null-terminated format string. For
             homogeneous Buffers, this should be set to
             ``format_descriptor<T>::value``.
         :param shape: Shape of the tensor (1 entry per dimension).
         :param strides: Number of bytes between adjacent entries (for each
             per dimension).
         :param readonly: Flag to indicate if the underlying storage may be
             written to.
      \endrst */
     static memoryview from_buffer(
         void *ptr, ssize_t itemsize, const char *format,
         detail::any_container<ssize_t> shape,
         detail::any_container<ssize_t> strides, bool readonly = false);
 
     static memoryview from_buffer(
         const void *ptr, ssize_t itemsize, const char *format,
         detail::any_container<ssize_t> shape,
         detail::any_container<ssize_t> strides) {
         return memoryview::from_buffer(
             const_cast<void *>(ptr), itemsize, format, std::move(shape), std::move(strides), true);
     }
 
     template<typename T>
     static memoryview from_buffer(
         T *ptr, detail::any_container<ssize_t> shape,
         detail::any_container<ssize_t> strides, bool readonly = false) {
         return memoryview::from_buffer(
             reinterpret_cast<void*>(ptr), sizeof(T),
             format_descriptor<T>::value, shape, strides, readonly);
     }
 
     template<typename T>
     static memoryview from_buffer(
         const T *ptr, detail::any_container<ssize_t> shape,
         detail::any_container<ssize_t> strides) {
         return memoryview::from_buffer(
             const_cast<T*>(ptr), shape, strides, true);
     }
 
 #if PY_MAJOR_VERSION >= 3
     /** \rst
         Creates ``memoryview`` from static memory.
 
         This method is meant for providing a ``memoryview`` for C/C++ buffer not
         managed by Python. The caller is responsible for managing the lifetime
         of ``mem``, which MUST outlive the memoryview constructed here.
 
         This method is not available in Python 2.
 
         See also: Python C API documentation for `PyMemoryView_FromBuffer`_.
 
         .. _PyMemoryView_FromMemory: https://docs.python.org/c-api/memoryview.html#c.PyMemoryView_FromMemory
      \endrst */
     static memoryview from_memory(void *mem, ssize_t size, bool readonly = false) {
         PyObject* ptr = PyMemoryView_FromMemory(
             reinterpret_cast<char*>(mem), size,
             (readonly) ? PyBUF_READ : PyBUF_WRITE);
         if (!ptr)
             pybind11_fail("Could not allocate memoryview object!");
         return memoryview(object(ptr, stolen_t{}));
     }
 
     static memoryview from_memory(const void *mem, ssize_t size) {
         return memoryview::from_memory(const_cast<void*>(mem), size, true);
     }
 
 #ifdef PYBIND11_HAS_STRING_VIEW
     static memoryview from_memory(std::string_view mem) {
         return from_memory(const_cast<char*>(mem.data()), static_cast<ssize_t>(mem.size()), true);
     }
 #endif
 
 #endif
 };
 
 /// @cond DUPLICATE
 inline memoryview memoryview::from_buffer(
     void *ptr, ssize_t itemsize, const char* format,
     detail::any_container<ssize_t> shape,
     detail::any_container<ssize_t> strides, bool readonly) {
     size_t ndim = shape->size();
     if (ndim != strides->size())
         pybind11_fail("memoryview: shape length doesn't match strides length");
     ssize_t size = ndim != 0u ? 1 : 0;
     for (size_t i = 0; i < ndim; ++i)
         size *= (*shape)[i];
     Py_buffer view;
     view.buf = ptr;
     view.obj = nullptr;
     view.len = size * itemsize;
     view.readonly = static_cast<int>(readonly);
     view.itemsize = itemsize;
     view.format = const_cast<char*>(format);
     view.ndim = static_cast<int>(ndim);
     view.shape = shape->data();
     view.strides = strides->data();
     view.suboffsets = nullptr;
     view.internal = nullptr;
     PyObject* obj = PyMemoryView_FromBuffer(&view);
     if (!obj)
         throw error_already_set();
     return memoryview(object(obj, stolen_t{}));
 }
 /// @endcond
 /// @} pytypes
 
 /// \addtogroup python_builtins
 /// @{
 
 /// Get the length of a Python object.
 inline size_t len(handle h) {
     ssize_t result = PyObject_Length(h.ptr());
     if (result < 0)
         throw error_already_set();
     return (size_t) result;
 }
 
 /// Get the length hint of a Python object.
 /// Returns 0 when this cannot be determined.
 inline size_t len_hint(handle h) {
 #if PY_VERSION_HEX >= 0x03040000
     ssize_t result = PyObject_LengthHint(h.ptr(), 0);
 #else
     ssize_t result = PyObject_Length(h.ptr());
 #endif
     if (result < 0) {
         // Sometimes a length can't be determined at all (eg generators)
         // In which case simply return 0
         PyErr_Clear();
         return 0;
     }
     return (size_t) result;
 }
 
 inline str repr(handle h) {
     PyObject *str_value = PyObject_Repr(h.ptr());
     if (!str_value) throw error_already_set();
 #if PY_MAJOR_VERSION < 3
     PyObject *unicode = PyUnicode_FromEncodedObject(str_value, "utf-8", nullptr);
     Py_XDECREF(str_value); str_value = unicode;
     if (!str_value) throw error_already_set();
 #endif
     return reinterpret_steal<str>(str_value);
 }
 
 inline iterator iter(handle obj) {
     PyObject *result = PyObject_GetIter(obj.ptr());
     if (!result) { throw error_already_set(); }
     return reinterpret_steal<iterator>(result);
 }
 /// @} python_builtins
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 template <typename D> iterator object_api<D>::begin() const { return iter(derived()); }
 template <typename D> iterator object_api<D>::end() const { return iterator::sentinel(); }
 template <typename D> item_accessor object_api<D>::operator[](handle key) const {
     return {derived(), reinterpret_borrow<object>(key)};
 }
 template <typename D> item_accessor object_api<D>::operator[](const char *key) const {
     return {derived(), pybind11::str(key)};
 }
 template <typename D> obj_attr_accessor object_api<D>::attr(handle key) const {
     return {derived(), reinterpret_borrow<object>(key)};
 }
 template <typename D> str_attr_accessor object_api<D>::attr(const char *key) const {
     return {derived(), key};
 }
 template <typename D> args_proxy object_api<D>::operator*() const {
     return args_proxy(derived().ptr());
 }
 template <typename D> template <typename T> bool object_api<D>::contains(T &&item) const {
     return attr("__contains__")(std::forward<T>(item)).template cast<bool>();
 }
 
 template <typename D>
 pybind11::str object_api<D>::str() const { return pybind11::str(derived()); }
 
 template <typename D>
 str_attr_accessor object_api<D>::doc() const { return attr("__doc__"); }
 
 template <typename D>
 handle object_api<D>::get_type() const { return type::handle_of(derived()); }
 
 template <typename D>
 bool object_api<D>::rich_compare(object_api const &other, int value) const {
     int rv = PyObject_RichCompareBool(derived().ptr(), other.derived().ptr(), value);
     if (rv == -1)
         throw error_already_set();
     return rv == 1;
 }
 
 #define PYBIND11_MATH_OPERATOR_UNARY(op, fn)                                   \
     template <typename D> object object_api<D>::op() const {                   \
         object result = reinterpret_steal<object>(fn(derived().ptr()));        \
         if (!result.ptr())                                                     \
             throw error_already_set();                                         \
         return result;                                                         \
     }
 
 #define PYBIND11_MATH_OPERATOR_BINARY(op, fn)                                  \
     template <typename D>                                                      \
     object object_api<D>::op(object_api const &other) const {                  \
         object result = reinterpret_steal<object>(                             \
             fn(derived().ptr(), other.derived().ptr()));                       \
         if (!result.ptr())                                                     \
             throw error_already_set();                                         \
         return result;                                                         \
     }
 
 PYBIND11_MATH_OPERATOR_UNARY (operator~,   PyNumber_Invert)
 PYBIND11_MATH_OPERATOR_UNARY (operator-,   PyNumber_Negative)
 PYBIND11_MATH_OPERATOR_BINARY(operator+,   PyNumber_Add)
 PYBIND11_MATH_OPERATOR_BINARY(operator+=,  PyNumber_InPlaceAdd)
 PYBIND11_MATH_OPERATOR_BINARY(operator-,   PyNumber_Subtract)
 PYBIND11_MATH_OPERATOR_BINARY(operator-=,  PyNumber_InPlaceSubtract)
 PYBIND11_MATH_OPERATOR_BINARY(operator*,   PyNumber_Multiply)
 PYBIND11_MATH_OPERATOR_BINARY(operator*=,  PyNumber_InPlaceMultiply)
 PYBIND11_MATH_OPERATOR_BINARY(operator/,   PyNumber_TrueDivide)
 PYBIND11_MATH_OPERATOR_BINARY(operator/=,  PyNumber_InPlaceTrueDivide)
 PYBIND11_MATH_OPERATOR_BINARY(operator|,   PyNumber_Or)
 PYBIND11_MATH_OPERATOR_BINARY(operator|=,  PyNumber_InPlaceOr)
 PYBIND11_MATH_OPERATOR_BINARY(operator&,   PyNumber_And)
 PYBIND11_MATH_OPERATOR_BINARY(operator&=,  PyNumber_InPlaceAnd)
 PYBIND11_MATH_OPERATOR_BINARY(operator^,   PyNumber_Xor)
 PYBIND11_MATH_OPERATOR_BINARY(operator^=,  PyNumber_InPlaceXor)
 PYBIND11_MATH_OPERATOR_BINARY(operator<<,  PyNumber_Lshift)
 PYBIND11_MATH_OPERATOR_BINARY(operator<<=, PyNumber_InPlaceLshift)
 PYBIND11_MATH_OPERATOR_BINARY(operator>>,  PyNumber_Rshift)
 PYBIND11_MATH_OPERATOR_BINARY(operator>>=, PyNumber_InPlaceRshift)
 
 #undef PYBIND11_MATH_OPERATOR_UNARY
 #undef PYBIND11_MATH_OPERATOR_BINARY
 
 PYBIND11_NAMESPACE_END(detail)
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)