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1 /*
2     pybind11/detail/class.h: Python C API implementation details for py::class_
3 
4     Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
5 
6     All rights reserved. Use of this source code is governed by a
7     BSD-style license that can be found in the LICENSE file.
8 */
9 
10 #pragma once
11 
12 #include "../attr.h"
13 #include "../options.h"
14 
15 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)16 PYBIND11_NAMESPACE_BEGIN(detail)
17 
18 #if PY_VERSION_HEX >= 0x03030000 && !defined(PYPY_VERSION)
19 #  define PYBIND11_BUILTIN_QUALNAME
20 #  define PYBIND11_SET_OLDPY_QUALNAME(obj, nameobj)
21 #else
22 // In pre-3.3 Python, we still set __qualname__ so that we can produce reliable function type
23 // signatures; in 3.3+ this macro expands to nothing:
24 #  define PYBIND11_SET_OLDPY_QUALNAME(obj, nameobj) setattr((PyObject *) obj, "__qualname__", nameobj)
25 #endif
26 
27 inline std::string get_fully_qualified_tp_name(PyTypeObject *type) {
28 #if !defined(PYPY_VERSION)
29     return type->tp_name;
30 #else
31     auto module_name = handle((PyObject *) type).attr("__module__").cast<std::string>();
32     if (module_name == PYBIND11_BUILTINS_MODULE)
33         return type->tp_name;
34     else
35         return std::move(module_name) + "." + type->tp_name;
36 #endif
37 }
38 
type_incref(PyTypeObject * type)39 inline PyTypeObject *type_incref(PyTypeObject *type) {
40     Py_INCREF(type);
41     return type;
42 }
43 
44 #if !defined(PYPY_VERSION)
45 
46 /// `pybind11_static_property.__get__()`: Always pass the class instead of the instance.
pybind11_static_get(PyObject * self,PyObject *,PyObject * cls)47 extern "C" inline PyObject *pybind11_static_get(PyObject *self, PyObject * /*ob*/, PyObject *cls) {
48     return PyProperty_Type.tp_descr_get(self, cls, cls);
49 }
50 
51 /// `pybind11_static_property.__set__()`: Just like the above `__get__()`.
pybind11_static_set(PyObject * self,PyObject * obj,PyObject * value)52 extern "C" inline int pybind11_static_set(PyObject *self, PyObject *obj, PyObject *value) {
53     PyObject *cls = PyType_Check(obj) ? obj : (PyObject *) Py_TYPE(obj);
54     return PyProperty_Type.tp_descr_set(self, cls, value);
55 }
56 
57 /** A `static_property` is the same as a `property` but the `__get__()` and `__set__()`
58     methods are modified to always use the object type instead of a concrete instance.
59     Return value: New reference. */
make_static_property_type()60 inline PyTypeObject *make_static_property_type() {
61     constexpr auto *name = "pybind11_static_property";
62     auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
63 
64     /* Danger zone: from now (and until PyType_Ready), make sure to
65        issue no Python C API calls which could potentially invoke the
66        garbage collector (the GC will call type_traverse(), which will in
67        turn find the newly constructed type in an invalid state) */
68     auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
69     if (!heap_type)
70         pybind11_fail("make_static_property_type(): error allocating type!");
71 
72     heap_type->ht_name = name_obj.inc_ref().ptr();
73 #ifdef PYBIND11_BUILTIN_QUALNAME
74     heap_type->ht_qualname = name_obj.inc_ref().ptr();
75 #endif
76 
77     auto type = &heap_type->ht_type;
78     type->tp_name = name;
79     type->tp_base = type_incref(&PyProperty_Type);
80     type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
81     type->tp_descr_get = pybind11_static_get;
82     type->tp_descr_set = pybind11_static_set;
83 
84     if (PyType_Ready(type) < 0)
85         pybind11_fail("make_static_property_type(): failure in PyType_Ready()!");
86 
87     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
88     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
89 
90     return type;
91 }
92 
93 #else // PYPY
94 
95 /** PyPy has some issues with the above C API, so we evaluate Python code instead.
96     This function will only be called once so performance isn't really a concern.
97     Return value: New reference. */
make_static_property_type()98 inline PyTypeObject *make_static_property_type() {
99     auto d = dict();
100     PyObject *result = PyRun_String(R"(\
101         class pybind11_static_property(property):
102             def __get__(self, obj, cls):
103                 return property.__get__(self, cls, cls)
104 
105             def __set__(self, obj, value):
106                 cls = obj if isinstance(obj, type) else type(obj)
107                 property.__set__(self, cls, value)
108         )", Py_file_input, d.ptr(), d.ptr()
109     );
110     if (result == nullptr)
111         throw error_already_set();
112     Py_DECREF(result);
113     return (PyTypeObject *) d["pybind11_static_property"].cast<object>().release().ptr();
114 }
115 
116 #endif // PYPY
117 
118 /** Types with static properties need to handle `Type.static_prop = x` in a specific way.
119     By default, Python replaces the `static_property` itself, but for wrapped C++ types
120     we need to call `static_property.__set__()` in order to propagate the new value to
121     the underlying C++ data structure. */
pybind11_meta_setattro(PyObject * obj,PyObject * name,PyObject * value)122 extern "C" inline int pybind11_meta_setattro(PyObject* obj, PyObject* name, PyObject* value) {
123     // Use `_PyType_Lookup()` instead of `PyObject_GetAttr()` in order to get the raw
124     // descriptor (`property`) instead of calling `tp_descr_get` (`property.__get__()`).
125     PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
126 
127     // The following assignment combinations are possible:
128     //   1. `Type.static_prop = value`             --> descr_set: `Type.static_prop.__set__(value)`
129     //   2. `Type.static_prop = other_static_prop` --> setattro:  replace existing `static_prop`
130     //   3. `Type.regular_attribute = value`       --> setattro:  regular attribute assignment
131     const auto static_prop = (PyObject *) get_internals().static_property_type;
132     const auto call_descr_set = descr && value && PyObject_IsInstance(descr, static_prop)
133                                 && !PyObject_IsInstance(value, static_prop);
134     if (call_descr_set) {
135         // Call `static_property.__set__()` instead of replacing the `static_property`.
136 #if !defined(PYPY_VERSION)
137         return Py_TYPE(descr)->tp_descr_set(descr, obj, value);
138 #else
139         if (PyObject *result = PyObject_CallMethod(descr, "__set__", "OO", obj, value)) {
140             Py_DECREF(result);
141             return 0;
142         } else {
143             return -1;
144         }
145 #endif
146     } else {
147         // Replace existing attribute.
148         return PyType_Type.tp_setattro(obj, name, value);
149     }
150 }
151 
152 #if PY_MAJOR_VERSION >= 3
153 /**
154  * Python 3's PyInstanceMethod_Type hides itself via its tp_descr_get, which prevents aliasing
155  * methods via cls.attr("m2") = cls.attr("m1"): instead the tp_descr_get returns a plain function,
156  * when called on a class, or a PyMethod, when called on an instance.  Override that behaviour here
157  * to do a special case bypass for PyInstanceMethod_Types.
158  */
pybind11_meta_getattro(PyObject * obj,PyObject * name)159 extern "C" inline PyObject *pybind11_meta_getattro(PyObject *obj, PyObject *name) {
160     PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
161     if (descr && PyInstanceMethod_Check(descr)) {
162         Py_INCREF(descr);
163         return descr;
164     }
165     else {
166         return PyType_Type.tp_getattro(obj, name);
167     }
168 }
169 #endif
170 
171 /// metaclass `__call__` function that is used to create all pybind11 objects.
pybind11_meta_call(PyObject * type,PyObject * args,PyObject * kwargs)172 extern "C" inline PyObject *pybind11_meta_call(PyObject *type, PyObject *args, PyObject *kwargs) {
173 
174     // use the default metaclass call to create/initialize the object
175     PyObject *self = PyType_Type.tp_call(type, args, kwargs);
176     if (self == nullptr) {
177         return nullptr;
178     }
179 
180     // This must be a pybind11 instance
181     auto instance = reinterpret_cast<detail::instance *>(self);
182 
183     // Ensure that the base __init__ function(s) were called
184     for (const auto &vh : values_and_holders(instance)) {
185         if (!vh.holder_constructed()) {
186             PyErr_Format(PyExc_TypeError, "%.200s.__init__() must be called when overriding __init__",
187                          get_fully_qualified_tp_name(vh.type->type).c_str());
188             Py_DECREF(self);
189             return nullptr;
190         }
191     }
192 
193     return self;
194 }
195 
196 /// Cleanup the type-info for a pybind11-registered type.
pybind11_meta_dealloc(PyObject * obj)197 extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
198     auto *type = (PyTypeObject *) obj;
199     auto &internals = get_internals();
200 
201     // A pybind11-registered type will:
202     // 1) be found in internals.registered_types_py
203     // 2) have exactly one associated `detail::type_info`
204     auto found_type = internals.registered_types_py.find(type);
205     if (found_type != internals.registered_types_py.end() &&
206         found_type->second.size() == 1 &&
207         found_type->second[0]->type == type) {
208 
209         auto *tinfo = found_type->second[0];
210         auto tindex = std::type_index(*tinfo->cpptype);
211         internals.direct_conversions.erase(tindex);
212 
213         if (tinfo->module_local)
214             registered_local_types_cpp().erase(tindex);
215         else
216             internals.registered_types_cpp.erase(tindex);
217         internals.registered_types_py.erase(tinfo->type);
218 
219         // Actually just `std::erase_if`, but that's only available in C++20
220         auto &cache = internals.inactive_override_cache;
221         for (auto it = cache.begin(), last = cache.end(); it != last; ) {
222             if (it->first == (PyObject *) tinfo->type)
223                 it = cache.erase(it);
224             else
225                 ++it;
226         }
227 
228         delete tinfo;
229     }
230 
231     PyType_Type.tp_dealloc(obj);
232 }
233 
234 /** This metaclass is assigned by default to all pybind11 types and is required in order
235     for static properties to function correctly. Users may override this using `py::metaclass`.
236     Return value: New reference. */
make_default_metaclass()237 inline PyTypeObject* make_default_metaclass() {
238     constexpr auto *name = "pybind11_type";
239     auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
240 
241     /* Danger zone: from now (and until PyType_Ready), make sure to
242        issue no Python C API calls which could potentially invoke the
243        garbage collector (the GC will call type_traverse(), which will in
244        turn find the newly constructed type in an invalid state) */
245     auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
246     if (!heap_type)
247         pybind11_fail("make_default_metaclass(): error allocating metaclass!");
248 
249     heap_type->ht_name = name_obj.inc_ref().ptr();
250 #ifdef PYBIND11_BUILTIN_QUALNAME
251     heap_type->ht_qualname = name_obj.inc_ref().ptr();
252 #endif
253 
254     auto type = &heap_type->ht_type;
255     type->tp_name = name;
256     type->tp_base = type_incref(&PyType_Type);
257     type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
258 
259     type->tp_call = pybind11_meta_call;
260 
261     type->tp_setattro = pybind11_meta_setattro;
262 #if PY_MAJOR_VERSION >= 3
263     type->tp_getattro = pybind11_meta_getattro;
264 #endif
265 
266     type->tp_dealloc = pybind11_meta_dealloc;
267 
268     if (PyType_Ready(type) < 0)
269         pybind11_fail("make_default_metaclass(): failure in PyType_Ready()!");
270 
271     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
272     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
273 
274     return type;
275 }
276 
277 /// For multiple inheritance types we need to recursively register/deregister base pointers for any
278 /// base classes with pointers that are difference from the instance value pointer so that we can
279 /// correctly recognize an offset base class pointer. This calls a function with any offset base ptrs.
traverse_offset_bases(void * valueptr,const detail::type_info * tinfo,instance * self,bool (* f)(void *,instance *))280 inline void traverse_offset_bases(void *valueptr, const detail::type_info *tinfo, instance *self,
281         bool (*f)(void * /*parentptr*/, instance * /*self*/)) {
282     for (handle h : reinterpret_borrow<tuple>(tinfo->type->tp_bases)) {
283         if (auto parent_tinfo = get_type_info((PyTypeObject *) h.ptr())) {
284             for (auto &c : parent_tinfo->implicit_casts) {
285                 if (c.first == tinfo->cpptype) {
286                     auto *parentptr = c.second(valueptr);
287                     if (parentptr != valueptr)
288                         f(parentptr, self);
289                     traverse_offset_bases(parentptr, parent_tinfo, self, f);
290                     break;
291                 }
292             }
293         }
294     }
295 }
296 
register_instance_impl(void * ptr,instance * self)297 inline bool register_instance_impl(void *ptr, instance *self) {
298     get_internals().registered_instances.emplace(ptr, self);
299     return true; // unused, but gives the same signature as the deregister func
300 }
deregister_instance_impl(void * ptr,instance * self)301 inline bool deregister_instance_impl(void *ptr, instance *self) {
302     auto &registered_instances = get_internals().registered_instances;
303     auto range = registered_instances.equal_range(ptr);
304     for (auto it = range.first; it != range.second; ++it) {
305         if (self == it->second) {
306             registered_instances.erase(it);
307             return true;
308         }
309     }
310     return false;
311 }
312 
register_instance(instance * self,void * valptr,const type_info * tinfo)313 inline void register_instance(instance *self, void *valptr, const type_info *tinfo) {
314     register_instance_impl(valptr, self);
315     if (!tinfo->simple_ancestors)
316         traverse_offset_bases(valptr, tinfo, self, register_instance_impl);
317 }
318 
deregister_instance(instance * self,void * valptr,const type_info * tinfo)319 inline bool deregister_instance(instance *self, void *valptr, const type_info *tinfo) {
320     bool ret = deregister_instance_impl(valptr, self);
321     if (!tinfo->simple_ancestors)
322         traverse_offset_bases(valptr, tinfo, self, deregister_instance_impl);
323     return ret;
324 }
325 
326 /// Instance creation function for all pybind11 types. It allocates the internal instance layout for
327 /// holding C++ objects and holders.  Allocation is done lazily (the first time the instance is cast
328 /// to a reference or pointer), and initialization is done by an `__init__` function.
make_new_instance(PyTypeObject * type)329 inline PyObject *make_new_instance(PyTypeObject *type) {
330 #if defined(PYPY_VERSION)
331     // PyPy gets tp_basicsize wrong (issue 2482) under multiple inheritance when the first inherited
332     // object is a a plain Python type (i.e. not derived from an extension type).  Fix it.
333     ssize_t instance_size = static_cast<ssize_t>(sizeof(instance));
334     if (type->tp_basicsize < instance_size) {
335         type->tp_basicsize = instance_size;
336     }
337 #endif
338     PyObject *self = type->tp_alloc(type, 0);
339     auto inst = reinterpret_cast<instance *>(self);
340     // Allocate the value/holder internals:
341     inst->allocate_layout();
342 
343     return self;
344 }
345 
346 /// Instance creation function for all pybind11 types. It only allocates space for the
347 /// C++ object, but doesn't call the constructor -- an `__init__` function must do that.
pybind11_object_new(PyTypeObject * type,PyObject *,PyObject *)348 extern "C" inline PyObject *pybind11_object_new(PyTypeObject *type, PyObject *, PyObject *) {
349     return make_new_instance(type);
350 }
351 
352 /// An `__init__` function constructs the C++ object. Users should provide at least one
353 /// of these using `py::init` or directly with `.def(__init__, ...)`. Otherwise, the
354 /// following default function will be used which simply throws an exception.
pybind11_object_init(PyObject * self,PyObject *,PyObject *)355 extern "C" inline int pybind11_object_init(PyObject *self, PyObject *, PyObject *) {
356     PyTypeObject *type = Py_TYPE(self);
357     std::string msg = get_fully_qualified_tp_name(type) + ": No constructor defined!";
358     PyErr_SetString(PyExc_TypeError, msg.c_str());
359     return -1;
360 }
361 
add_patient(PyObject * nurse,PyObject * patient)362 inline void add_patient(PyObject *nurse, PyObject *patient) {
363     auto &internals = get_internals();
364     auto instance = reinterpret_cast<detail::instance *>(nurse);
365     instance->has_patients = true;
366     Py_INCREF(patient);
367     internals.patients[nurse].push_back(patient);
368 }
369 
clear_patients(PyObject * self)370 inline void clear_patients(PyObject *self) {
371     auto instance = reinterpret_cast<detail::instance *>(self);
372     auto &internals = get_internals();
373     auto pos = internals.patients.find(self);
374     assert(pos != internals.patients.end());
375     // Clearing the patients can cause more Python code to run, which
376     // can invalidate the iterator. Extract the vector of patients
377     // from the unordered_map first.
378     auto patients = std::move(pos->second);
379     internals.patients.erase(pos);
380     instance->has_patients = false;
381     for (PyObject *&patient : patients)
382         Py_CLEAR(patient);
383 }
384 
385 /// Clears all internal data from the instance and removes it from registered instances in
386 /// preparation for deallocation.
clear_instance(PyObject * self)387 inline void clear_instance(PyObject *self) {
388     auto instance = reinterpret_cast<detail::instance *>(self);
389 
390     // Deallocate any values/holders, if present:
391     for (auto &v_h : values_and_holders(instance)) {
392         if (v_h) {
393 
394             // We have to deregister before we call dealloc because, for virtual MI types, we still
395             // need to be able to get the parent pointers.
396             if (v_h.instance_registered() && !deregister_instance(instance, v_h.value_ptr(), v_h.type))
397                 pybind11_fail("pybind11_object_dealloc(): Tried to deallocate unregistered instance!");
398 
399             if (instance->owned || v_h.holder_constructed())
400                 v_h.type->dealloc(v_h);
401         }
402     }
403     // Deallocate the value/holder layout internals:
404     instance->deallocate_layout();
405 
406     if (instance->weakrefs)
407         PyObject_ClearWeakRefs(self);
408 
409     PyObject **dict_ptr = _PyObject_GetDictPtr(self);
410     if (dict_ptr)
411         Py_CLEAR(*dict_ptr);
412 
413     if (instance->has_patients)
414         clear_patients(self);
415 }
416 
417 /// Instance destructor function for all pybind11 types. It calls `type_info.dealloc`
418 /// to destroy the C++ object itself, while the rest is Python bookkeeping.
pybind11_object_dealloc(PyObject * self)419 extern "C" inline void pybind11_object_dealloc(PyObject *self) {
420     clear_instance(self);
421 
422     auto type = Py_TYPE(self);
423     type->tp_free(self);
424 
425 #if PY_VERSION_HEX < 0x03080000
426     // `type->tp_dealloc != pybind11_object_dealloc` means that we're being called
427     // as part of a derived type's dealloc, in which case we're not allowed to decref
428     // the type here. For cross-module compatibility, we shouldn't compare directly
429     // with `pybind11_object_dealloc`, but with the common one stashed in internals.
430     auto pybind11_object_type = (PyTypeObject *) get_internals().instance_base;
431     if (type->tp_dealloc == pybind11_object_type->tp_dealloc)
432         Py_DECREF(type);
433 #else
434     // This was not needed before Python 3.8 (Python issue 35810)
435     // https://github.com/pybind/pybind11/issues/1946
436     Py_DECREF(type);
437 #endif
438 }
439 
440 /** Create the type which can be used as a common base for all classes.  This is
441     needed in order to satisfy Python's requirements for multiple inheritance.
442     Return value: New reference. */
make_object_base_type(PyTypeObject * metaclass)443 inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
444     constexpr auto *name = "pybind11_object";
445     auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
446 
447     /* Danger zone: from now (and until PyType_Ready), make sure to
448        issue no Python C API calls which could potentially invoke the
449        garbage collector (the GC will call type_traverse(), which will in
450        turn find the newly constructed type in an invalid state) */
451     auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
452     if (!heap_type)
453         pybind11_fail("make_object_base_type(): error allocating type!");
454 
455     heap_type->ht_name = name_obj.inc_ref().ptr();
456 #ifdef PYBIND11_BUILTIN_QUALNAME
457     heap_type->ht_qualname = name_obj.inc_ref().ptr();
458 #endif
459 
460     auto type = &heap_type->ht_type;
461     type->tp_name = name;
462     type->tp_base = type_incref(&PyBaseObject_Type);
463     type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
464     type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
465 
466     type->tp_new = pybind11_object_new;
467     type->tp_init = pybind11_object_init;
468     type->tp_dealloc = pybind11_object_dealloc;
469 
470     /* Support weak references (needed for the keep_alive feature) */
471     type->tp_weaklistoffset = offsetof(instance, weakrefs);
472 
473     if (PyType_Ready(type) < 0)
474         pybind11_fail("PyType_Ready failed in make_object_base_type():" + error_string());
475 
476     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
477     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
478 
479     assert(!PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
480     return (PyObject *) heap_type;
481 }
482 
483 /// dynamic_attr: Support for `d = instance.__dict__`.
pybind11_get_dict(PyObject * self,void *)484 extern "C" inline PyObject *pybind11_get_dict(PyObject *self, void *) {
485     PyObject *&dict = *_PyObject_GetDictPtr(self);
486     if (!dict)
487         dict = PyDict_New();
488     Py_XINCREF(dict);
489     return dict;
490 }
491 
492 /// dynamic_attr: Support for `instance.__dict__ = dict()`.
pybind11_set_dict(PyObject * self,PyObject * new_dict,void *)493 extern "C" inline int pybind11_set_dict(PyObject *self, PyObject *new_dict, void *) {
494     if (!PyDict_Check(new_dict)) {
495         PyErr_Format(PyExc_TypeError, "__dict__ must be set to a dictionary, not a '%.200s'",
496                      get_fully_qualified_tp_name(Py_TYPE(new_dict)).c_str());
497         return -1;
498     }
499     PyObject *&dict = *_PyObject_GetDictPtr(self);
500     Py_INCREF(new_dict);
501     Py_CLEAR(dict);
502     dict = new_dict;
503     return 0;
504 }
505 
506 /// dynamic_attr: Allow the garbage collector to traverse the internal instance `__dict__`.
pybind11_traverse(PyObject * self,visitproc visit,void * arg)507 extern "C" inline int pybind11_traverse(PyObject *self, visitproc visit, void *arg) {
508     PyObject *&dict = *_PyObject_GetDictPtr(self);
509     Py_VISIT(dict);
510     return 0;
511 }
512 
513 /// dynamic_attr: Allow the GC to clear the dictionary.
pybind11_clear(PyObject * self)514 extern "C" inline int pybind11_clear(PyObject *self) {
515     PyObject *&dict = *_PyObject_GetDictPtr(self);
516     Py_CLEAR(dict);
517     return 0;
518 }
519 
520 /// Give instances of this type a `__dict__` and opt into garbage collection.
enable_dynamic_attributes(PyHeapTypeObject * heap_type)521 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
522     auto type = &heap_type->ht_type;
523     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
524     type->tp_dictoffset = type->tp_basicsize; // place dict at the end
525     type->tp_basicsize += (ssize_t)sizeof(PyObject *); // and allocate enough space for it
526     type->tp_traverse = pybind11_traverse;
527     type->tp_clear = pybind11_clear;
528 
529     static PyGetSetDef getset[] = {
530         {const_cast<char*>("__dict__"), pybind11_get_dict, pybind11_set_dict, nullptr, nullptr},
531         {nullptr, nullptr, nullptr, nullptr, nullptr}
532     };
533     type->tp_getset = getset;
534 }
535 
536 /// buffer_protocol: Fill in the view as specified by flags.
pybind11_getbuffer(PyObject * obj,Py_buffer * view,int flags)537 extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int flags) {
538     // Look for a `get_buffer` implementation in this type's info or any bases (following MRO).
539     type_info *tinfo = nullptr;
540     for (auto type : reinterpret_borrow<tuple>(Py_TYPE(obj)->tp_mro)) {
541         tinfo = get_type_info((PyTypeObject *) type.ptr());
542         if (tinfo && tinfo->get_buffer)
543             break;
544     }
545     if (view == nullptr || !tinfo || !tinfo->get_buffer) {
546         if (view)
547             view->obj = nullptr;
548         PyErr_SetString(PyExc_BufferError, "pybind11_getbuffer(): Internal error");
549         return -1;
550     }
551     std::memset(view, 0, sizeof(Py_buffer));
552     buffer_info *info = tinfo->get_buffer(obj, tinfo->get_buffer_data);
553     if ((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE && info->readonly) {
554         delete info;
555         // view->obj = nullptr;  // Was just memset to 0, so not necessary
556         PyErr_SetString(PyExc_BufferError, "Writable buffer requested for readonly storage");
557         return -1;
558     }
559     view->obj = obj;
560     view->ndim = 1;
561     view->internal = info;
562     view->buf = info->ptr;
563     view->itemsize = info->itemsize;
564     view->len = view->itemsize;
565     for (auto s : info->shape)
566         view->len *= s;
567     view->readonly = info->readonly;
568     if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT)
569         view->format = const_cast<char *>(info->format.c_str());
570     if ((flags & PyBUF_STRIDES) == PyBUF_STRIDES) {
571         view->ndim = (int) info->ndim;
572         view->strides = &info->strides[0];
573         view->shape = &info->shape[0];
574     }
575     Py_INCREF(view->obj);
576     return 0;
577 }
578 
579 /// buffer_protocol: Release the resources of the buffer.
pybind11_releasebuffer(PyObject *,Py_buffer * view)580 extern "C" inline void pybind11_releasebuffer(PyObject *, Py_buffer *view) {
581     delete (buffer_info *) view->internal;
582 }
583 
584 /// Give this type a buffer interface.
enable_buffer_protocol(PyHeapTypeObject * heap_type)585 inline void enable_buffer_protocol(PyHeapTypeObject *heap_type) {
586     heap_type->ht_type.tp_as_buffer = &heap_type->as_buffer;
587 #if PY_MAJOR_VERSION < 3
588     heap_type->ht_type.tp_flags |= Py_TPFLAGS_HAVE_NEWBUFFER;
589 #endif
590 
591     heap_type->as_buffer.bf_getbuffer = pybind11_getbuffer;
592     heap_type->as_buffer.bf_releasebuffer = pybind11_releasebuffer;
593 }
594 
595 /** Create a brand new Python type according to the `type_record` specification.
596     Return value: New reference. */
make_new_python_type(const type_record & rec)597 inline PyObject* make_new_python_type(const type_record &rec) {
598     auto name = reinterpret_steal<object>(PYBIND11_FROM_STRING(rec.name));
599 
600     auto qualname = name;
601     if (rec.scope && !PyModule_Check(rec.scope.ptr()) && hasattr(rec.scope, "__qualname__")) {
602 #if PY_MAJOR_VERSION >= 3
603         qualname = reinterpret_steal<object>(
604             PyUnicode_FromFormat("%U.%U", rec.scope.attr("__qualname__").ptr(), name.ptr()));
605 #else
606         qualname = str(rec.scope.attr("__qualname__").cast<std::string>() + "." + rec.name);
607 #endif
608     }
609 
610     object module_;
611     if (rec.scope) {
612         if (hasattr(rec.scope, "__module__"))
613             module_ = rec.scope.attr("__module__");
614         else if (hasattr(rec.scope, "__name__"))
615             module_ = rec.scope.attr("__name__");
616     }
617 
618     auto full_name = c_str(
619 #if !defined(PYPY_VERSION)
620         module_ ? str(module_).cast<std::string>() + "." + rec.name :
621 #endif
622         rec.name);
623 
624     char *tp_doc = nullptr;
625     if (rec.doc && options::show_user_defined_docstrings()) {
626         /* Allocate memory for docstring (using PyObject_MALLOC, since
627            Python will free this later on) */
628         size_t size = strlen(rec.doc) + 1;
629         tp_doc = (char *) PyObject_MALLOC(size);
630         memcpy((void *) tp_doc, rec.doc, size);
631     }
632 
633     auto &internals = get_internals();
634     auto bases = tuple(rec.bases);
635     auto base = (bases.empty()) ? internals.instance_base
636                                     : bases[0].ptr();
637 
638     /* Danger zone: from now (and until PyType_Ready), make sure to
639        issue no Python C API calls which could potentially invoke the
640        garbage collector (the GC will call type_traverse(), which will in
641        turn find the newly constructed type in an invalid state) */
642     auto metaclass = rec.metaclass.ptr() ? (PyTypeObject *) rec.metaclass.ptr()
643                                          : internals.default_metaclass;
644 
645     auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
646     if (!heap_type)
647         pybind11_fail(std::string(rec.name) + ": Unable to create type object!");
648 
649     heap_type->ht_name = name.release().ptr();
650 #ifdef PYBIND11_BUILTIN_QUALNAME
651     heap_type->ht_qualname = qualname.inc_ref().ptr();
652 #endif
653 
654     auto type = &heap_type->ht_type;
655     type->tp_name = full_name;
656     type->tp_doc = tp_doc;
657     type->tp_base = type_incref((PyTypeObject *)base);
658     type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
659     if (!bases.empty())
660         type->tp_bases = bases.release().ptr();
661 
662     /* Don't inherit base __init__ */
663     type->tp_init = pybind11_object_init;
664 
665     /* Supported protocols */
666     type->tp_as_number = &heap_type->as_number;
667     type->tp_as_sequence = &heap_type->as_sequence;
668     type->tp_as_mapping = &heap_type->as_mapping;
669 #if PY_VERSION_HEX >= 0x03050000
670     type->tp_as_async = &heap_type->as_async;
671 #endif
672 
673     /* Flags */
674     type->tp_flags |= Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE;
675 #if PY_MAJOR_VERSION < 3
676     type->tp_flags |= Py_TPFLAGS_CHECKTYPES;
677 #endif
678     if (!rec.is_final)
679         type->tp_flags |= Py_TPFLAGS_BASETYPE;
680 
681     if (rec.dynamic_attr)
682         enable_dynamic_attributes(heap_type);
683 
684     if (rec.buffer_protocol)
685         enable_buffer_protocol(heap_type);
686 
687     if (PyType_Ready(type) < 0)
688         pybind11_fail(std::string(rec.name) + ": PyType_Ready failed (" + error_string() + ")!");
689 
690     assert(rec.dynamic_attr ? PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC)
691                             : !PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
692 
693     /* Register type with the parent scope */
694     if (rec.scope)
695         setattr(rec.scope, rec.name, (PyObject *) type);
696     else
697         Py_INCREF(type); // Keep it alive forever (reference leak)
698 
699     if (module_) // Needed by pydoc
700         setattr((PyObject *) type, "__module__", module_);
701 
702     PYBIND11_SET_OLDPY_QUALNAME(type, qualname);
703 
704     return (PyObject *) type;
705 }
706 
707 PYBIND11_NAMESPACE_END(detail)
708 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
709