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 /*
     pybind11/detail/internals.h: Internal data structure and related functions
 
     Copyright (c) 2017 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 "../pytypes.h"
 #include <exception>
 
 /// Tracks the `internals` and `type_info` ABI version independent of the main library version.
 ///
 /// Some portions of the code use an ABI that is conditional depending on this
 /// version number.  That allows ABI-breaking changes to be "pre-implemented".
 /// Once the default version number is incremented, the conditional logic that
 /// no longer applies can be removed.  Additionally, users that need not
 /// maintain ABI compatibility can increase the version number in order to take
 /// advantage of any functionality/efficiency improvements that depend on the
 /// newer ABI.
 ///
 /// WARNING: If you choose to manually increase the ABI version, note that
 /// pybind11 may not be tested as thoroughly with a non-default ABI version, and
 /// further ABI-incompatible changes may be made before the ABI is officially
 /// changed to the new version.
 #ifndef PYBIND11_INTERNALS_VERSION
 #    define PYBIND11_INTERNALS_VERSION 4
 #endif
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 using ExceptionTranslator = void (*)(std::exception_ptr);
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
 // Forward declarations
 inline PyTypeObject *make_static_property_type();
 inline PyTypeObject *make_default_metaclass();
 inline PyObject *make_object_base_type(PyTypeObject *metaclass);
 
 // The old Python Thread Local Storage (TLS) API is deprecated in Python 3.7 in favor of the new
 // Thread Specific Storage (TSS) API.
 #if PY_VERSION_HEX >= 0x03070000
 // Avoid unnecessary allocation of `Py_tss_t`, since we cannot use
 // `Py_LIMITED_API` anyway.
 #    if PYBIND11_INTERNALS_VERSION > 4
 #        define PYBIND11_TLS_KEY_REF Py_tss_t &
 #        ifdef __GNUC__
 // Clang on macOS warns due to `Py_tss_NEEDS_INIT` not specifying an initializer
 // for every field.
 #            define PYBIND11_TLS_KEY_INIT(var)                                                    \
                 _Pragma("GCC diagnostic push")                                         /**/       \
                     _Pragma("GCC diagnostic ignored \"-Wmissing-field-initializers\"") /**/       \
                     Py_tss_t var                                                                  \
                     = Py_tss_NEEDS_INIT;                                                          \
                 _Pragma("GCC diagnostic pop")
 #        else
 #            define PYBIND11_TLS_KEY_INIT(var) Py_tss_t var = Py_tss_NEEDS_INIT;
 #        endif
 #        define PYBIND11_TLS_KEY_CREATE(var) (PyThread_tss_create(&(var)) == 0)
 #        define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get(&(key))
 #        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set(&(key), (value))
 #        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set(&(key), nullptr)
 #        define PYBIND11_TLS_FREE(key) PyThread_tss_delete(&(key))
 #    else
 #        define PYBIND11_TLS_KEY_REF Py_tss_t *
 #        define PYBIND11_TLS_KEY_INIT(var) Py_tss_t *var = nullptr;
 #        define PYBIND11_TLS_KEY_CREATE(var)                                                      \
             (((var) = PyThread_tss_alloc()) != nullptr && (PyThread_tss_create((var)) == 0))
 #        define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get((key))
 #        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set((key), (value))
 #        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set((key), nullptr)
 #        define PYBIND11_TLS_FREE(key) PyThread_tss_free(key)
 #    endif
 #else
 // Usually an int but a long on Cygwin64 with Python 3.x
 #    define PYBIND11_TLS_KEY_REF decltype(PyThread_create_key())
 #    define PYBIND11_TLS_KEY_INIT(var) PYBIND11_TLS_KEY_REF var = 0;
 #    define PYBIND11_TLS_KEY_CREATE(var) (((var) = PyThread_create_key()) != -1)
 #    define PYBIND11_TLS_GET_VALUE(key) PyThread_get_key_value((key))
 #    if PY_MAJOR_VERSION < 3 || defined(PYPY_VERSION)
 // On CPython < 3.4 and on PyPy, `PyThread_set_key_value` strangely does not set
 // the value if it has already been set.  Instead, it must first be deleted and
 // then set again.
 inline void tls_replace_value(PYBIND11_TLS_KEY_REF key, void *value) {
     PyThread_delete_key_value(key);
     PyThread_set_key_value(key, value);
 }
 #        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_delete_key_value(key)
 #        define PYBIND11_TLS_REPLACE_VALUE(key, value)                                            \
             ::pybind11::detail::tls_replace_value((key), (value))
 #    else
 #        define PYBIND11_TLS_DELETE_VALUE(key) PyThread_set_key_value((key), nullptr)
 #        define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_set_key_value((key), (value))
 #    endif
 #    define PYBIND11_TLS_FREE(key) (void) key
 #endif
 
 // Python loads modules by default with dlopen with the RTLD_LOCAL flag; under libc++ and possibly
 // other STLs, this means `typeid(A)` from one module won't equal `typeid(A)` from another module
 // even when `A` is the same, non-hidden-visibility type (e.g. from a common include).  Under
 // libstdc++, this doesn't happen: equality and the type_index hash are based on the type name,
 // which works.  If not under a known-good stl, provide our own name-based hash and equality
 // functions that use the type name.
 #if defined(__GLIBCXX__)
 inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) { return lhs == rhs; }
 using type_hash = std::hash<std::type_index>;
 using type_equal_to = std::equal_to<std::type_index>;
 #else
 inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) {
     return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
 }
 
 struct type_hash {
     size_t operator()(const std::type_index &t) const {
         size_t hash = 5381;
         const char *ptr = t.name();
         while (auto c = static_cast<unsigned char>(*ptr++))
             hash = (hash * 33) ^ c;
         return hash;
     }
 };
 
 struct type_equal_to {
     bool operator()(const std::type_index &lhs, const std::type_index &rhs) const {
         return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
     }
 };
 #endif
 
 template <typename value_type>
 using type_map = std::unordered_map<std::type_index, value_type, type_hash, type_equal_to>;
 
 struct override_hash {
     inline size_t operator()(const std::pair<const PyObject *, const char *>& v) const {
         size_t value = std::hash<const void *>()(v.first);
         value ^= std::hash<const void *>()(v.second) + 0x9e3779b9 + (value<<6) + (value>>2);
         return value;
     }
 };
 
 /// Internal data structure used to track registered instances and types.
 /// Whenever binary incompatible changes are made to this structure,
 /// `PYBIND11_INTERNALS_VERSION` must be incremented.
 struct internals {
     type_map<type_info *> registered_types_cpp; // std::type_index -> pybind11's type information
     std::unordered_map<PyTypeObject *, std::vector<type_info *>> registered_types_py; // PyTypeObject* -> base type_info(s)
     std::unordered_multimap<const void *, instance*> registered_instances; // void * -> instance*
     std::unordered_set<std::pair<const PyObject *, const char *>, override_hash> inactive_override_cache;
     type_map<std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
     std::unordered_map<const PyObject *, std::vector<PyObject *>> patients;
     std::forward_list<ExceptionTranslator> registered_exception_translators;
     std::unordered_map<std::string, void *> shared_data; // Custom data to be shared across extensions
 #if PYBIND11_INTERNALS_VERSION == 4
     std::vector<PyObject *> unused_loader_patient_stack_remove_at_v5;
 #endif
     std::forward_list<std::string> static_strings; // Stores the std::strings backing detail::c_str()
     PyTypeObject *static_property_type;
     PyTypeObject *default_metaclass;
     PyObject *instance_base;
 #if defined(WITH_THREAD)
     PYBIND11_TLS_KEY_INIT(tstate)
 #    if PYBIND11_INTERNALS_VERSION > 4
     PYBIND11_TLS_KEY_INIT(loader_life_support_tls_key)
 #    endif // PYBIND11_INTERNALS_VERSION > 4
     PyInterpreterState *istate = nullptr;
     ~internals() {
 #    if PYBIND11_INTERNALS_VERSION > 4
         PYBIND11_TLS_FREE(loader_life_support_tls_key);
 #    endif // PYBIND11_INTERNALS_VERSION > 4
 
         // This destructor is called *after* Py_Finalize() in finalize_interpreter().
         // That *SHOULD BE* fine. The following details what happens when PyThread_tss_free is
         // called. PYBIND11_TLS_FREE is PyThread_tss_free on python 3.7+. On older python, it does
         // nothing. PyThread_tss_free calls PyThread_tss_delete and PyMem_RawFree.
         // PyThread_tss_delete just calls TlsFree (on Windows) or pthread_key_delete (on *NIX).
         // Neither of those have anything to do with CPython internals. PyMem_RawFree *requires*
         // that the `tstate` be allocated with the CPython allocator.
         PYBIND11_TLS_FREE(tstate);
     }
 #endif
 };
 
 /// Additional type information which does not fit into the PyTypeObject.
 /// Changes to this struct also require bumping `PYBIND11_INTERNALS_VERSION`.
 struct type_info {
     PyTypeObject *type;
     const std::type_info *cpptype;
     size_t type_size, type_align, holder_size_in_ptrs;
     void *(*operator_new)(size_t);
     void (*init_instance)(instance *, const void *);
     void (*dealloc)(value_and_holder &v_h);
     std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
     std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;
     std::vector<bool (*)(PyObject *, void *&)> *direct_conversions;
     buffer_info *(*get_buffer)(PyObject *, void *) = nullptr;
     void *get_buffer_data = nullptr;
     void *(*module_local_load)(PyObject *, const type_info *) = nullptr;
     /* A simple type never occurs as a (direct or indirect) parent
      * of a class that makes use of multiple inheritance.
      * A type can be simple even if it has non-simple ancestors as long as it has no descendants.
      */
     bool simple_type : 1;
     /* True if there is no multiple inheritance in this type's inheritance tree */
     bool simple_ancestors : 1;
     /* for base vs derived holder_type checks */
     bool default_holder : 1;
     /* true if this is a type registered with py::module_local */
     bool module_local : 1;
 };
 
 /// On MSVC, debug and release builds are not ABI-compatible!
 #if defined(_MSC_VER) && defined(_DEBUG)
 #  define PYBIND11_BUILD_TYPE "_debug"
 #else
 #  define PYBIND11_BUILD_TYPE ""
 #endif
 
 /// Let's assume that different compilers are ABI-incompatible.
 /// A user can manually set this string if they know their
 /// compiler is compatible.
 #ifndef PYBIND11_COMPILER_TYPE
 #  if defined(_MSC_VER)
 #    define PYBIND11_COMPILER_TYPE "_msvc"
 #  elif defined(__INTEL_COMPILER)
 #    define PYBIND11_COMPILER_TYPE "_icc"
 #  elif defined(__clang__)
 #    define PYBIND11_COMPILER_TYPE "_clang"
 #  elif defined(__PGI)
 #    define PYBIND11_COMPILER_TYPE "_pgi"
 #  elif defined(__MINGW32__)
 #    define PYBIND11_COMPILER_TYPE "_mingw"
 #  elif defined(__CYGWIN__)
 #    define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
 #  elif defined(__GNUC__)
 #    define PYBIND11_COMPILER_TYPE "_gcc"
 #  else
 #    define PYBIND11_COMPILER_TYPE "_unknown"
 #  endif
 #endif
 
 /// Also standard libs
 #ifndef PYBIND11_STDLIB
 #  if defined(_LIBCPP_VERSION)
 #    define PYBIND11_STDLIB "_libcpp"
 #  elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
 #    define PYBIND11_STDLIB "_libstdcpp"
 #  else
 #    define PYBIND11_STDLIB ""
 #  endif
 #endif
 
 /// On Linux/OSX, changes in __GXX_ABI_VERSION__ indicate ABI incompatibility.
 #ifndef PYBIND11_BUILD_ABI
 #  if defined(__GXX_ABI_VERSION)
 #    define PYBIND11_BUILD_ABI "_cxxabi" PYBIND11_TOSTRING(__GXX_ABI_VERSION)
 #  else
 #    define PYBIND11_BUILD_ABI ""
 #  endif
 #endif
 
 #ifndef PYBIND11_INTERNALS_KIND
 #  if defined(WITH_THREAD)
 #    define PYBIND11_INTERNALS_KIND ""
 #  else
 #    define PYBIND11_INTERNALS_KIND "_without_thread"
 #  endif
 #endif
 
 #define PYBIND11_INTERNALS_ID "__pybind11_internals_v" \
     PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
 
 #define PYBIND11_MODULE_LOCAL_ID "__pybind11_module_local_v" \
     PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
 
 /// Each module locally stores a pointer to the `internals` data. The data
 /// itself is shared among modules with the same `PYBIND11_INTERNALS_ID`.
 inline internals **&get_internals_pp() {
     static internals **internals_pp = nullptr;
     return internals_pp;
 }
 
 #if PY_VERSION_HEX >= 0x03030000
 // forward decl
 inline void translate_exception(std::exception_ptr);
 
 template <class T,
           enable_if_t<std::is_same<std::nested_exception, remove_cvref_t<T>>::value, int> = 0>
 bool handle_nested_exception(const T &exc, const std::exception_ptr &p) {
     std::exception_ptr nested = exc.nested_ptr();
     if (nested != nullptr && nested != p) {
         translate_exception(nested);
         return true;
     }
     return false;
 }
 
 template <class T,
           enable_if_t<!std::is_same<std::nested_exception, remove_cvref_t<T>>::value, int> = 0>
 bool handle_nested_exception(const T &exc, const std::exception_ptr &p) {
     if (auto *nep = dynamic_cast<const std::nested_exception *>(std::addressof(exc))) {
         return handle_nested_exception(*nep, p);
     }
     return false;
 }
 
 #else
 
 template <class T>
 bool handle_nested_exception(const T &, std::exception_ptr &) {
     return false;
 }
 #endif
 
 inline bool raise_err(PyObject *exc_type, const char *msg) {
 #if PY_VERSION_HEX >= 0x03030000
     if (PyErr_Occurred()) {
         raise_from(exc_type, msg);
         return true;
     }
 #endif
     PyErr_SetString(exc_type, msg);
     return false;
 }
 
 inline void translate_exception(std::exception_ptr p) {
     if (!p) {
         return;
     }
     try {
         std::rethrow_exception(p);
     } catch (error_already_set &e) {
         handle_nested_exception(e, p);
         e.restore();
         return;
     } catch (const builtin_exception &e) {
         // Could not use template since it's an abstract class.
         if (auto *nep = dynamic_cast<const std::nested_exception *>(std::addressof(e))) {
             handle_nested_exception(*nep, p);
         }
         e.set_error();
         return;
     } catch (const std::bad_alloc &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_MemoryError, e.what());
         return;
     } catch (const std::domain_error &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_ValueError, e.what());
         return;
     } catch (const std::invalid_argument &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_ValueError, e.what());
         return;
     } catch (const std::length_error &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_ValueError, e.what());
         return;
     } catch (const std::out_of_range &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_IndexError, e.what());
         return;
     } catch (const std::range_error &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_ValueError, e.what());
         return;
     } catch (const std::overflow_error &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_OverflowError, e.what());
         return;
     } catch (const std::exception &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_RuntimeError, e.what());
         return;
     } catch (const std::nested_exception &e) {
         handle_nested_exception(e, p);
         raise_err(PyExc_RuntimeError, "Caught an unknown nested exception!");
         return;
     } catch (...) {
         raise_err(PyExc_RuntimeError, "Caught an unknown exception!");
         return;
     }
 }
 
 #if !defined(__GLIBCXX__)
 inline void translate_local_exception(std::exception_ptr p) {
     try {
         if (p) std::rethrow_exception(p);
     } catch (error_already_set &e)       { e.restore();   return;
     } catch (const builtin_exception &e) { e.set_error(); return;
     }
 }
 #endif
 
 /// Return a reference to the current `internals` data
 PYBIND11_NOINLINE internals &get_internals() {
     auto **&internals_pp = get_internals_pp();
     if (internals_pp && *internals_pp)
         return **internals_pp;
 
     // Ensure that the GIL is held since we will need to make Python calls.
     // Cannot use py::gil_scoped_acquire here since that constructor calls get_internals.
     struct gil_scoped_acquire_local {
         gil_scoped_acquire_local() : state (PyGILState_Ensure()) {}
         ~gil_scoped_acquire_local() { PyGILState_Release(state); }
         const PyGILState_STATE state;
     } gil;
 
     PYBIND11_STR_TYPE id(PYBIND11_INTERNALS_ID);
     auto builtins = handle(PyEval_GetBuiltins());
     if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
         internals_pp = static_cast<internals **>(capsule(builtins[id]));
 
         // We loaded builtins through python's builtins, which means that our `error_already_set`
         // and `builtin_exception` may be different local classes than the ones set up in the
         // initial exception translator, below, so add another for our local exception classes.
         //
         // libstdc++ doesn't require this (types there are identified only by name)
         // libc++ with CPython doesn't require this (types are explicitly exported)
         // libc++ with PyPy still need it, awaiting further investigation
 #if !defined(__GLIBCXX__)
         (*internals_pp)->registered_exception_translators.push_front(&translate_local_exception);
 #endif
     } else {
         if (!internals_pp) internals_pp = new internals*();
         auto *&internals_ptr = *internals_pp;
         internals_ptr = new internals();
 #if defined(WITH_THREAD)
 
 #    if PY_VERSION_HEX < 0x03090000
         PyEval_InitThreads();
 #    endif
         PyThreadState *tstate = PyThreadState_Get();
         if (!PYBIND11_TLS_KEY_CREATE(internals_ptr->tstate)) {
             pybind11_fail("get_internals: could not successfully initialize the tstate TSS key!");
         }
         PYBIND11_TLS_REPLACE_VALUE(internals_ptr->tstate, tstate);
 
 #    if PYBIND11_INTERNALS_VERSION > 4
         if (!PYBIND11_TLS_KEY_CREATE(internals_ptr->loader_life_support_tls_key)) {
             pybind11_fail("get_internals: could not successfully initialize the "
                           "loader_life_support TSS key!");
         }
 #    endif
         internals_ptr->istate = tstate->interp;
 #endif
         builtins[id] = capsule(internals_pp);
         internals_ptr->registered_exception_translators.push_front(&translate_exception);
         internals_ptr->static_property_type = make_static_property_type();
         internals_ptr->default_metaclass = make_default_metaclass();
         internals_ptr->instance_base = make_object_base_type(internals_ptr->default_metaclass);
     }
     return **internals_pp;
 }
 
 // the internals struct (above) is shared between all the modules. local_internals are only
 // for a single module. Any changes made to internals may require an update to
 // PYBIND11_INTERNALS_VERSION, breaking backwards compatibility. local_internals is, by design,
 // restricted to a single module. Whether a module has local internals or not should not
 // impact any other modules, because the only things accessing the local internals is the
 // module that contains them.
 struct local_internals {
     type_map<type_info *> registered_types_cpp;
     std::forward_list<ExceptionTranslator> registered_exception_translators;
 #if defined(WITH_THREAD) && PYBIND11_INTERNALS_VERSION == 4
 
     // For ABI compatibility, we can't store the loader_life_support TLS key in
     // the `internals` struct directly.  Instead, we store it in `shared_data` and
     // cache a copy in `local_internals`.  If we allocated a separate TLS key for
     // each instance of `local_internals`, we could end up allocating hundreds of
     // TLS keys if hundreds of different pybind11 modules are loaded (which is a
     // plausible number).
     PYBIND11_TLS_KEY_INIT(loader_life_support_tls_key)
 
     // Holds the shared TLS key for the loader_life_support stack.
     struct shared_loader_life_support_data {
         PYBIND11_TLS_KEY_INIT(loader_life_support_tls_key)
         shared_loader_life_support_data() {
             if (!PYBIND11_TLS_KEY_CREATE(loader_life_support_tls_key)) {
                 pybind11_fail("local_internals: could not successfully initialize the "
                               "loader_life_support TLS key!");
             }
         }
         // We can't help but leak the TLS key, because Python never unloads extension modules.
     };
 
     local_internals() {
         auto &internals = get_internals();
         // Get or create the `loader_life_support_stack_key`.
         auto &ptr = internals.shared_data["_life_support"];
         if (!ptr) {
             ptr = new shared_loader_life_support_data;
         }
         loader_life_support_tls_key
             = static_cast<shared_loader_life_support_data *>(ptr)->loader_life_support_tls_key;
     }
 #endif //  defined(WITH_THREAD) && PYBIND11_INTERNALS_VERSION == 4
 };
 
 /// Works like `get_internals`, but for things which are locally registered.
 inline local_internals &get_local_internals() {
   static local_internals locals;
   return locals;
 }
 
 
 /// Constructs a std::string with the given arguments, stores it in `internals`, and returns its
 /// `c_str()`.  Such strings objects have a long storage duration -- the internal strings are only
 /// cleared when the program exits or after interpreter shutdown (when embedding), and so are
 /// suitable for c-style strings needed by Python internals (such as PyTypeObject's tp_name).
 template <typename... Args>
 const char *c_str(Args &&...args) {
     auto &strings = get_internals().static_strings;
     strings.emplace_front(std::forward<Args>(args)...);
     return strings.front().c_str();
 }
 
 PYBIND11_NAMESPACE_END(detail)
 
 /// Returns a named pointer that is shared among all extension modules (using the same
 /// pybind11 version) running in the current interpreter. Names starting with underscores
 /// are reserved for internal usage. Returns `nullptr` if no matching entry was found.
 PYBIND11_NOINLINE void *get_shared_data(const std::string &name) {
     auto &internals = detail::get_internals();
     auto it = internals.shared_data.find(name);
     return it != internals.shared_data.end() ? it->second : nullptr;
 }
 
 /// Set the shared data that can be later recovered by `get_shared_data()`.
 PYBIND11_NOINLINE void *set_shared_data(const std::string &name, void *data) {
     detail::get_internals().shared_data[name] = data;
     return data;
 }
 
 /// Returns a typed reference to a shared data entry (by using `get_shared_data()`) if
 /// such entry exists. Otherwise, a new object of default-constructible type `T` is
 /// added to the shared data under the given name and a reference to it is returned.
 template<typename T>
 T &get_or_create_shared_data(const std::string &name) {
     auto &internals = detail::get_internals();
     auto it = internals.shared_data.find(name);
     T *ptr = (T *) (it != internals.shared_data.end() ? it->second : nullptr);
     if (!ptr) {
         ptr = new T();
         internals.shared_data[name] = ptr;
     }
     return *ptr;
 }
 
 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)