2 pybind11/cast.h: Partial template specializations to cast between
5 Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
7 All rights reserved. Use of this source code is governed by a
8 BSD-style license that can be found in the LICENSE file.
14 #include "detail/typeid.h"
15 #include "detail/descr.h"
16 #include "detail/internals.h"
21 #if defined(PYBIND11_CPP17)
22 # if defined(__has_include)
23 # if __has_include(<string_view>)
24 # define PYBIND11_HAS_STRING_VIEW
26 # elif defined(_MSC_VER)
27 # define PYBIND11_HAS_STRING_VIEW
30 #ifdef PYBIND11_HAS_STRING_VIEW
31 #include <string_view>
34 NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
35 NAMESPACE_BEGIN(detail)
37 /// A life support system for temporary objects created by `type_caster::load()`.
38 /// Adding a patient will keep it alive up until the enclosing function returns.
39 class loader_life_support {
41 /// A new patient frame is created when a function is entered
42 loader_life_support() {
43 get_internals().loader_patient_stack.push_back(nullptr);
46 /// ... and destroyed after it returns
47 ~loader_life_support() {
48 auto &stack = get_internals().loader_patient_stack;
50 pybind11_fail("loader_life_support: internal error");
52 auto ptr = stack.back();
56 // A heuristic to reduce the stack's capacity (e.g. after long recursive calls)
57 if (stack.capacity() > 16 && stack.size() != 0 && stack.capacity() / stack.size() > 2)
58 stack.shrink_to_fit();
61 /// This can only be used inside a pybind11-bound function, either by `argument_loader`
62 /// at argument preparation time or by `py::cast()` at execution time.
63 PYBIND11_NOINLINE static void add_patient(handle h) {
64 auto &stack = get_internals().loader_patient_stack;
66 throw cast_error("When called outside a bound function, py::cast() cannot "
67 "do Python -> C++ conversions which require the creation "
68 "of temporary values");
70 auto &list_ptr = stack.back();
71 if (list_ptr == nullptr) {
72 list_ptr = PyList_New(1);
74 pybind11_fail("loader_life_support: error allocating list");
75 PyList_SET_ITEM(list_ptr, 0, h.inc_ref().ptr());
77 auto result = PyList_Append(list_ptr, h.ptr());
79 pybind11_fail("loader_life_support: error adding patient");
84 // Gets the cache entry for the given type, creating it if necessary. The return value is the pair
85 // returned by emplace, i.e. an iterator for the entry and a bool set to `true` if the entry was
87 inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_type_info_get_cache(PyTypeObject *type);
89 // Populates a just-created cache entry.
90 PYBIND11_NOINLINE inline void all_type_info_populate(PyTypeObject *t, std::vector<type_info *> &bases) {
91 std::vector<PyTypeObject *> check;
92 for (handle parent : reinterpret_borrow<tuple>(t->tp_bases))
93 check.push_back((PyTypeObject *) parent.ptr());
95 auto const &type_dict = get_internals().registered_types_py;
96 for (size_t i = 0; i < check.size(); i++) {
98 // Ignore Python2 old-style class super type:
99 if (!PyType_Check((PyObject *) type)) continue;
101 // Check `type` in the current set of registered python types:
102 auto it = type_dict.find(type);
103 if (it != type_dict.end()) {
104 // We found a cache entry for it, so it's either pybind-registered or has pre-computed
105 // pybind bases, but we have to make sure we haven't already seen the type(s) before: we
106 // want to follow Python/virtual C++ rules that there should only be one instance of a
108 for (auto *tinfo : it->second) {
109 // NB: Could use a second set here, rather than doing a linear search, but since
110 // having a large number of immediate pybind11-registered types seems fairly
111 // unlikely, that probably isn't worthwhile.
113 for (auto *known : bases) {
114 if (known == tinfo) { found = true; break; }
116 if (!found) bases.push_back(tinfo);
119 else if (type->tp_bases) {
120 // It's some python type, so keep follow its bases classes to look for one or more
122 if (i + 1 == check.size()) {
123 // When we're at the end, we can pop off the current element to avoid growing
124 // `check` when adding just one base (which is typical--i.e. when there is no
125 // multiple inheritance)
129 for (handle parent : reinterpret_borrow<tuple>(type->tp_bases))
130 check.push_back((PyTypeObject *) parent.ptr());
136 * Extracts vector of type_info pointers of pybind-registered roots of the given Python type. Will
137 * be just 1 pybind type for the Python type of a pybind-registered class, or for any Python-side
138 * derived class that uses single inheritance. Will contain as many types as required for a Python
139 * class that uses multiple inheritance to inherit (directly or indirectly) from multiple
140 * pybind-registered classes. Will be empty if neither the type nor any base classes are
143 * The value is cached for the lifetime of the Python type.
145 inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type) {
146 auto ins = all_type_info_get_cache(type);
148 // New cache entry: populate it
149 all_type_info_populate(type, ins.first->second);
151 return ins.first->second;
155 * Gets a single pybind11 type info for a python type. Returns nullptr if neither the type nor any
156 * ancestors are pybind11-registered. Throws an exception if there are multiple bases--use
157 * `all_type_info` instead if you want to support multiple bases.
159 PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) {
160 auto &bases = all_type_info(type);
161 if (bases.size() == 0)
163 if (bases.size() > 1)
164 pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
165 return bases.front();
168 inline detail::type_info *get_local_type_info(const std::type_index &tp) {
169 auto &locals = registered_local_types_cpp();
170 auto it = locals.find(tp);
171 if (it != locals.end())
176 inline detail::type_info *get_global_type_info(const std::type_index &tp) {
177 auto &types = get_internals().registered_types_cpp;
178 auto it = types.find(tp);
179 if (it != types.end())
184 /// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr.
185 PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_index &tp,
186 bool throw_if_missing = false) {
187 if (auto ltype = get_local_type_info(tp))
189 if (auto gtype = get_global_type_info(tp))
192 if (throw_if_missing) {
193 std::string tname = tp.name();
194 detail::clean_type_id(tname);
195 pybind11_fail("pybind11::detail::get_type_info: unable to find type info for \"" + tname + "\"");
200 PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp, bool throw_if_missing) {
201 detail::type_info *type_info = get_type_info(tp, throw_if_missing);
202 return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
205 struct value_and_holder {
208 const detail::type_info *type;
211 // Main constructor for a found value/holder:
212 value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index) :
213 inst{i}, index{index}, type{type},
214 vh{inst->simple_layout ? inst->simple_value_holder : &inst->nonsimple.values_and_holders[vpos]}
217 // Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
218 value_and_holder() : inst{nullptr} {}
220 // Used for past-the-end iterator
221 value_and_holder(size_t index) : index{index} {}
223 template <typename V = void> V *&value_ptr() const {
224 return reinterpret_cast<V *&>(vh[0]);
226 // True if this `value_and_holder` has a non-null value pointer
227 explicit operator bool() const { return value_ptr(); }
229 template <typename H> H &holder() const {
230 return reinterpret_cast<H &>(vh[1]);
232 bool holder_constructed() const {
233 return inst->simple_layout
234 ? inst->simple_holder_constructed
235 : inst->nonsimple.status[index] & instance::status_holder_constructed;
237 void set_holder_constructed(bool v = true) {
238 if (inst->simple_layout)
239 inst->simple_holder_constructed = v;
241 inst->nonsimple.status[index] |= instance::status_holder_constructed;
243 inst->nonsimple.status[index] &= (uint8_t) ~instance::status_holder_constructed;
245 bool instance_registered() const {
246 return inst->simple_layout
247 ? inst->simple_instance_registered
248 : inst->nonsimple.status[index] & instance::status_instance_registered;
250 void set_instance_registered(bool v = true) {
251 if (inst->simple_layout)
252 inst->simple_instance_registered = v;
254 inst->nonsimple.status[index] |= instance::status_instance_registered;
256 inst->nonsimple.status[index] &= (uint8_t) ~instance::status_instance_registered;
260 // Container for accessing and iterating over an instance's values/holders
261 struct values_and_holders {
264 using type_vec = std::vector<detail::type_info *>;
265 const type_vec &tinfo;
268 values_and_holders(instance *inst) : inst{inst}, tinfo(all_type_info(Py_TYPE(inst))) {}
273 const type_vec *types;
274 value_and_holder curr;
275 friend struct values_and_holders;
276 iterator(instance *inst, const type_vec *tinfo)
277 : inst{inst}, types{tinfo},
278 curr(inst /* instance */,
279 types->empty() ? nullptr : (*types)[0] /* type info */,
280 0, /* vpos: (non-simple types only): the first vptr comes first */
283 // Past-the-end iterator:
284 iterator(size_t end) : curr(end) {}
286 bool operator==(const iterator &other) { return curr.index == other.curr.index; }
287 bool operator!=(const iterator &other) { return curr.index != other.curr.index; }
288 iterator &operator++() {
289 if (!inst->simple_layout)
290 curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs;
292 curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr;
295 value_and_holder &operator*() { return curr; }
296 value_and_holder *operator->() { return &curr; }
299 iterator begin() { return iterator(inst, &tinfo); }
300 iterator end() { return iterator(tinfo.size()); }
302 iterator find(const type_info *find_type) {
303 auto it = begin(), endit = end();
304 while (it != endit && it->type != find_type) ++it;
308 size_t size() { return tinfo.size(); }
312 * Extracts C++ value and holder pointer references from an instance (which may contain multiple
313 * values/holders for python-side multiple inheritance) that match the given type. Throws an error
314 * if the given type (or ValueType, if omitted) is not a pybind11 base of the given instance. If
315 * `find_type` is omitted (or explicitly specified as nullptr) the first value/holder are returned,
316 * regardless of type (and the resulting .type will be nullptr).
318 * The returned object should be short-lived: in particular, it must not outlive the called-upon
321 PYBIND11_NOINLINE inline value_and_holder instance::get_value_and_holder(const type_info *find_type /*= nullptr default in common.h*/, bool throw_if_missing /*= true in common.h*/) {
322 // Optimize common case:
323 if (!find_type || Py_TYPE(this) == find_type->type)
324 return value_and_holder(this, find_type, 0, 0);
326 detail::values_and_holders vhs(this);
327 auto it = vhs.find(find_type);
331 if (!throw_if_missing)
332 return value_and_holder();
335 pybind11_fail("pybind11::detail::instance::get_value_and_holder: "
336 "type is not a pybind11 base of the given instance "
337 "(compile in debug mode for type details)");
339 pybind11_fail("pybind11::detail::instance::get_value_and_holder: `" +
340 std::string(find_type->type->tp_name) + "' is not a pybind11 base of the given `" +
341 std::string(Py_TYPE(this)->tp_name) + "' instance");
345 PYBIND11_NOINLINE inline void instance::allocate_layout() {
346 auto &tinfo = all_type_info(Py_TYPE(this));
348 const size_t n_types = tinfo.size();
351 pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types");
354 n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs();
356 // Simple path: no python-side multiple inheritance, and a small-enough holder
358 simple_value_holder[0] = nullptr;
359 simple_holder_constructed = false;
360 simple_instance_registered = false;
362 else { // multiple base types or a too-large holder
363 // Allocate space to hold: [v1*][h1][v2*][h2]...[bb...] where [vN*] is a value pointer,
364 // [hN] is the (uninitialized) holder instance for value N, and [bb...] is a set of bool
365 // values that tracks whether each associated holder has been initialized. Each [block] is
366 // padded, if necessary, to an integer multiple of sizeof(void *).
368 for (auto t : tinfo) {
369 space += 1; // value pointer
370 space += t->holder_size_in_ptrs; // holder instance
372 size_t flags_at = space;
373 space += size_in_ptrs(n_types); // status bytes (holder_constructed and instance_registered)
375 // Allocate space for flags, values, and holders, and initialize it to 0 (flags and values,
376 // in particular, need to be 0). Use Python's memory allocation functions: in Python 3.6
377 // they default to using pymalloc, which is designed to be efficient for small allocations
378 // like the one we're doing here; in earlier versions (and for larger allocations) they are
379 // just wrappers around malloc.
380 #if PY_VERSION_HEX >= 0x03050000
381 nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
382 if (!nonsimple.values_and_holders) throw std::bad_alloc();
384 nonsimple.values_and_holders = (void **) PyMem_New(void *, space);
385 if (!nonsimple.values_and_holders) throw std::bad_alloc();
386 std::memset(nonsimple.values_and_holders, 0, space * sizeof(void *));
388 nonsimple.status = reinterpret_cast<uint8_t *>(&nonsimple.values_and_holders[flags_at]);
393 PYBIND11_NOINLINE inline void instance::deallocate_layout() {
395 PyMem_Free(nonsimple.values_and_holders);
398 PYBIND11_NOINLINE inline bool isinstance_generic(handle obj, const std::type_info &tp) {
399 handle type = detail::get_type_handle(tp, false);
402 return isinstance(obj, type);
405 PYBIND11_NOINLINE inline std::string error_string() {
406 if (!PyErr_Occurred()) {
407 PyErr_SetString(PyExc_RuntimeError, "Unknown internal error occurred");
408 return "Unknown internal error occurred";
411 error_scope scope; // Preserve error state
413 std::string errorString;
415 errorString += handle(scope.type).attr("__name__").cast<std::string>();
419 errorString += (std::string) str(scope.value);
421 PyErr_NormalizeException(&scope.type, &scope.value, &scope.trace);
423 #if PY_MAJOR_VERSION >= 3
424 if (scope.trace != nullptr)
425 PyException_SetTraceback(scope.value, scope.trace);
428 #if !defined(PYPY_VERSION)
430 PyTracebackObject *trace = (PyTracebackObject *) scope.trace;
432 /* Get the deepest trace possible */
433 while (trace->tb_next)
434 trace = trace->tb_next;
436 PyFrameObject *frame = trace->tb_frame;
437 errorString += "\n\nAt:\n";
439 int lineno = PyFrame_GetLineNumber(frame);
441 " " + handle(frame->f_code->co_filename).cast<std::string>() +
442 "(" + std::to_string(lineno) + "): " +
443 handle(frame->f_code->co_name).cast<std::string>() + "\n";
444 frame = frame->f_back;
452 PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail::type_info *type ) {
453 auto &instances = get_internals().registered_instances;
454 auto range = instances.equal_range(ptr);
455 for (auto it = range.first; it != range.second; ++it) {
456 for (auto vh : values_and_holders(it->second)) {
458 return handle((PyObject *) it->second);
464 inline PyThreadState *get_thread_state_unchecked() {
465 #if defined(PYPY_VERSION)
466 return PyThreadState_GET();
467 #elif PY_VERSION_HEX < 0x03000000
468 return _PyThreadState_Current;
469 #elif PY_VERSION_HEX < 0x03050000
470 return (PyThreadState*) _Py_atomic_load_relaxed(&_PyThreadState_Current);
471 #elif PY_VERSION_HEX < 0x03050200
472 return (PyThreadState*) _PyThreadState_Current.value;
474 return _PyThreadState_UncheckedGet();
478 // Forward declarations
479 inline void keep_alive_impl(handle nurse, handle patient);
480 inline PyObject *make_new_instance(PyTypeObject *type);
482 class type_caster_generic {
484 PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info)
485 : typeinfo(get_type_info(type_info)), cpptype(&type_info) { }
487 type_caster_generic(const type_info *typeinfo)
488 : typeinfo(typeinfo), cpptype(typeinfo ? typeinfo->cpptype : nullptr) { }
490 bool load(handle src, bool convert) {
491 return load_impl<type_caster_generic>(src, convert);
494 PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent,
495 const detail::type_info *tinfo,
496 void *(*copy_constructor)(const void *),
497 void *(*move_constructor)(const void *),
498 const void *existing_holder = nullptr) {
499 if (!tinfo) // no type info: error will be set already
502 void *src = const_cast<void *>(_src);
504 return none().release();
506 auto it_instances = get_internals().registered_instances.equal_range(src);
507 for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
508 for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
509 if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype))
510 return handle((PyObject *) it_i->second).inc_ref();
514 auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
515 auto wrapper = reinterpret_cast<instance *>(inst.ptr());
516 wrapper->owned = false;
517 void *&valueptr = values_and_holders(wrapper).begin()->value_ptr();
520 case return_value_policy::automatic:
521 case return_value_policy::take_ownership:
523 wrapper->owned = true;
526 case return_value_policy::automatic_reference:
527 case return_value_policy::reference:
529 wrapper->owned = false;
532 case return_value_policy::copy:
533 if (copy_constructor)
534 valueptr = copy_constructor(src);
536 throw cast_error("return_value_policy = copy, but the "
537 "object is non-copyable!");
538 wrapper->owned = true;
541 case return_value_policy::move:
542 if (move_constructor)
543 valueptr = move_constructor(src);
544 else if (copy_constructor)
545 valueptr = copy_constructor(src);
547 throw cast_error("return_value_policy = move, but the "
548 "object is neither movable nor copyable!");
549 wrapper->owned = true;
552 case return_value_policy::reference_internal:
554 wrapper->owned = false;
555 keep_alive_impl(inst, parent);
559 throw cast_error("unhandled return_value_policy: should not happen!");
562 tinfo->init_instance(wrapper, existing_holder);
564 return inst.release();
567 // Base methods for generic caster; there are overridden in copyable_holder_caster
568 void load_value(value_and_holder &&v_h) {
569 auto *&vptr = v_h.value_ptr();
570 // Lazy allocation for unallocated values:
571 if (vptr == nullptr) {
572 auto *type = v_h.type ? v_h.type : typeinfo;
573 vptr = type->operator_new(type->type_size);
577 bool try_implicit_casts(handle src, bool convert) {
578 for (auto &cast : typeinfo->implicit_casts) {
579 type_caster_generic sub_caster(*cast.first);
580 if (sub_caster.load(src, convert)) {
581 value = cast.second(sub_caster.value);
587 bool try_direct_conversions(handle src) {
588 for (auto &converter : *typeinfo->direct_conversions) {
589 if (converter(src.ptr(), value))
594 void check_holder_compat() {}
596 PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
597 auto caster = type_caster_generic(ti);
598 if (caster.load(src, false))
603 /// Try to load with foreign typeinfo, if available. Used when there is no
604 /// native typeinfo, or when the native one wasn't able to produce a value.
605 PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) {
606 constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID;
607 const auto pytype = src.get_type();
608 if (!hasattr(pytype, local_key))
611 type_info *foreign_typeinfo = reinterpret_borrow<capsule>(getattr(pytype, local_key));
612 // Only consider this foreign loader if actually foreign and is a loader of the correct cpp type
613 if (foreign_typeinfo->module_local_load == &local_load
614 || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
617 if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) {
624 // Implementation of `load`; this takes the type of `this` so that it can dispatch the relevant
625 // bits of code between here and copyable_holder_caster where the two classes need different
626 // logic (without having to resort to virtual inheritance).
627 template <typename ThisT>
628 PYBIND11_NOINLINE bool load_impl(handle src, bool convert) {
629 if (!src) return false;
630 if (!typeinfo) return try_load_foreign_module_local(src);
632 // Defer accepting None to other overloads (if we aren't in convert mode):
633 if (!convert) return false;
638 auto &this_ = static_cast<ThisT &>(*this);
639 this_.check_holder_compat();
641 PyTypeObject *srctype = Py_TYPE(src.ptr());
643 // Case 1: If src is an exact type match for the target type then we can reinterpret_cast
644 // the instance's value pointer to the target type:
645 if (srctype == typeinfo->type) {
646 this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
649 // Case 2: We have a derived class
650 else if (PyType_IsSubtype(srctype, typeinfo->type)) {
651 auto &bases = all_type_info(srctype);
652 bool no_cpp_mi = typeinfo->simple_type;
654 // Case 2a: the python type is a Python-inherited derived class that inherits from just
655 // one simple (no MI) pybind11 class, or is an exact match, so the C++ instance is of
656 // the right type and we can use reinterpret_cast.
657 // (This is essentially the same as case 2b, but because not using multiple inheritance
658 // is extremely common, we handle it specially to avoid the loop iterator and type
659 // pointer lookup overhead)
660 if (bases.size() == 1 && (no_cpp_mi || bases.front()->type == typeinfo->type)) {
661 this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
664 // Case 2b: the python type inherits from multiple C++ bases. Check the bases to see if
665 // we can find an exact match (or, for a simple C++ type, an inherited match); if so, we
666 // can safely reinterpret_cast to the relevant pointer.
667 else if (bases.size() > 1) {
668 for (auto base : bases) {
669 if (no_cpp_mi ? PyType_IsSubtype(base->type, typeinfo->type) : base->type == typeinfo->type) {
670 this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder(base));
676 // Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match
677 // in the registered bases, above, so try implicit casting (needed for proper C++ casting
678 // when MI is involved).
679 if (this_.try_implicit_casts(src, convert))
683 // Perform an implicit conversion
685 for (auto &converter : typeinfo->implicit_conversions) {
686 auto temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
687 if (load_impl<ThisT>(temp, false)) {
688 loader_life_support::add_patient(temp);
692 if (this_.try_direct_conversions(src))
696 // Failed to match local typeinfo. Try again with global.
697 if (typeinfo->module_local) {
698 if (auto gtype = get_global_type_info(*typeinfo->cpptype)) {
700 return load(src, false);
704 // Global typeinfo has precedence over foreign module_local
705 return try_load_foreign_module_local(src);
709 // Called to do type lookup and wrap the pointer and type in a pair when a dynamic_cast
710 // isn't needed or can't be used. If the type is unknown, sets the error and returns a pair
711 // with .second = nullptr. (p.first = nullptr is not an error: it becomes None).
712 PYBIND11_NOINLINE static std::pair<const void *, const type_info *> src_and_type(
713 const void *src, const std::type_info &cast_type, const std::type_info *rtti_type = nullptr) {
714 if (auto *tpi = get_type_info(cast_type))
715 return {src, const_cast<const type_info *>(tpi)};
717 // Not found, set error:
718 std::string tname = rtti_type ? rtti_type->name() : cast_type.name();
719 detail::clean_type_id(tname);
720 std::string msg = "Unregistered type : " + tname;
721 PyErr_SetString(PyExc_TypeError, msg.c_str());
722 return {nullptr, nullptr};
725 const type_info *typeinfo = nullptr;
726 const std::type_info *cpptype = nullptr;
727 void *value = nullptr;
731 * Determine suitable casting operator for pointer-or-lvalue-casting type casters. The type caster
732 * needs to provide `operator T*()` and `operator T&()` operators.
734 * If the type supports moving the value away via an `operator T&&() &&` method, it should use
735 * `movable_cast_op_type` instead.
737 template <typename T>
739 conditional_t<std::is_pointer<remove_reference_t<T>>::value,
740 typename std::add_pointer<intrinsic_t<T>>::type,
741 typename std::add_lvalue_reference<intrinsic_t<T>>::type>;
744 * Determine suitable casting operator for a type caster with a movable value. Such a type caster
745 * needs to provide `operator T*()`, `operator T&()`, and `operator T&&() &&`. The latter will be
746 * called in appropriate contexts where the value can be moved rather than copied.
748 * These operator are automatically provided when using the PYBIND11_TYPE_CASTER macro.
750 template <typename T>
751 using movable_cast_op_type =
752 conditional_t<std::is_pointer<typename std::remove_reference<T>::type>::value,
753 typename std::add_pointer<intrinsic_t<T>>::type,
754 conditional_t<std::is_rvalue_reference<T>::value,
755 typename std::add_rvalue_reference<intrinsic_t<T>>::type,
756 typename std::add_lvalue_reference<intrinsic_t<T>>::type>>;
758 // std::is_copy_constructible isn't quite enough: it lets std::vector<T> (and similar) through when
759 // T is non-copyable, but code containing such a copy constructor fails to actually compile.
760 template <typename T, typename SFINAE = void> struct is_copy_constructible : std::is_copy_constructible<T> {};
762 // Specialization for types that appear to be copy constructible but also look like stl containers
763 // (we specifically check for: has `value_type` and `reference` with `reference = value_type&`): if
764 // so, copy constructability depends on whether the value_type is copy constructible.
765 template <typename Container> struct is_copy_constructible<Container, enable_if_t<all_of<
766 std::is_copy_constructible<Container>,
767 std::is_same<typename Container::value_type &, typename Container::reference>
768 >::value>> : is_copy_constructible<typename Container::value_type> {};
770 #if !defined(PYBIND11_CPP17)
771 // Likewise for std::pair before C++17 (which mandates that the copy constructor not exist when the
772 // two types aren't themselves copy constructible).
773 template <typename T1, typename T2> struct is_copy_constructible<std::pair<T1, T2>>
774 : all_of<is_copy_constructible<T1>, is_copy_constructible<T2>> {};
777 /// Generic type caster for objects stored on the heap
778 template <typename type> class type_caster_base : public type_caster_generic {
779 using itype = intrinsic_t<type>;
781 static PYBIND11_DESCR name() { return type_descr(_<type>()); }
783 type_caster_base() : type_caster_base(typeid(type)) { }
784 explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
786 static handle cast(const itype &src, return_value_policy policy, handle parent) {
787 if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
788 policy = return_value_policy::copy;
789 return cast(&src, policy, parent);
792 static handle cast(itype &&src, return_value_policy, handle parent) {
793 return cast(&src, return_value_policy::move, parent);
796 // Returns a (pointer, type_info) pair taking care of necessary RTTI type lookup for a
797 // polymorphic type. If the instance isn't derived, returns the non-RTTI base version.
798 template <typename T = itype, enable_if_t<std::is_polymorphic<T>::value, int> = 0>
799 static std::pair<const void *, const type_info *> src_and_type(const itype *src) {
800 const void *vsrc = src;
801 auto &cast_type = typeid(itype);
802 const std::type_info *instance_type = nullptr;
804 instance_type = &typeid(*src);
805 if (!same_type(cast_type, *instance_type)) {
806 // This is a base pointer to a derived type; if it is a pybind11-registered type, we
807 // can get the correct derived pointer (which may be != base pointer) by a
808 // dynamic_cast to most derived type:
809 if (auto *tpi = get_type_info(*instance_type))
810 return {dynamic_cast<const void *>(src), const_cast<const type_info *>(tpi)};
813 // Otherwise we have either a nullptr, an `itype` pointer, or an unknown derived pointer, so
815 return type_caster_generic::src_and_type(vsrc, cast_type, instance_type);
818 // Non-polymorphic type, so no dynamic casting; just call the generic version directly
819 template <typename T = itype, enable_if_t<!std::is_polymorphic<T>::value, int> = 0>
820 static std::pair<const void *, const type_info *> src_and_type(const itype *src) {
821 return type_caster_generic::src_and_type(src, typeid(itype));
824 static handle cast(const itype *src, return_value_policy policy, handle parent) {
825 auto st = src_and_type(src);
826 return type_caster_generic::cast(
827 st.first, policy, parent, st.second,
828 make_copy_constructor(src), make_move_constructor(src));
831 static handle cast_holder(const itype *src, const void *holder) {
832 auto st = src_and_type(src);
833 return type_caster_generic::cast(
834 st.first, return_value_policy::take_ownership, {}, st.second,
835 nullptr, nullptr, holder);
838 template <typename T> using cast_op_type = cast_op_type<T>;
840 operator itype*() { return (type *) value; }
841 operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
844 using Constructor = void *(*)(const void *);
846 /* Only enabled when the types are {copy,move}-constructible *and* when the type
847 does not have a private operator new implementation. */
848 template <typename T, typename = enable_if_t<is_copy_constructible<T>::value>>
849 static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) {
850 return [](const void *arg) -> void * {
851 return new T(*reinterpret_cast<const T *>(arg));
855 template <typename T, typename = enable_if_t<std::is_move_constructible<T>::value>>
856 static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast<T *>(x))), Constructor{}) {
857 return [](const void *arg) -> void * {
858 return new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg))));
862 static Constructor make_copy_constructor(...) { return nullptr; }
863 static Constructor make_move_constructor(...) { return nullptr; }
866 template <typename type, typename SFINAE = void> class type_caster : public type_caster_base<type> { };
867 template <typename type> using make_caster = type_caster<intrinsic_t<type>>;
869 // Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
870 template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
871 return caster.operator typename make_caster<T>::template cast_op_type<T>();
873 template <typename T> typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
874 cast_op(make_caster<T> &&caster) {
875 return std::move(caster).operator
876 typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>();
879 template <typename type> class type_caster<std::reference_wrapper<type>> {
881 using caster_t = make_caster<type>;
883 using subcaster_cast_op_type = typename caster_t::template cast_op_type<type>;
884 static_assert(std::is_same<typename std::remove_const<type>::type &, subcaster_cast_op_type>::value,
885 "std::reference_wrapper<T> caster requires T to have a caster with an `T &` operator");
887 bool load(handle src, bool convert) { return subcaster.load(src, convert); }
888 static PYBIND11_DESCR name() { return caster_t::name(); }
889 static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
890 // It is definitely wrong to take ownership of this pointer, so mask that rvp
891 if (policy == return_value_policy::take_ownership || policy == return_value_policy::automatic)
892 policy = return_value_policy::automatic_reference;
893 return caster_t::cast(&src.get(), policy, parent);
895 template <typename T> using cast_op_type = std::reference_wrapper<type>;
896 operator std::reference_wrapper<type>() { return subcaster.operator subcaster_cast_op_type&(); }
899 #define PYBIND11_TYPE_CASTER(type, py_name) \
903 static PYBIND11_DESCR name() { return type_descr(py_name); } \
904 template <typename T_, enable_if_t<std::is_same<type, remove_cv_t<T_>>::value, int> = 0> \
905 static handle cast(T_ *src, return_value_policy policy, handle parent) { \
906 if (!src) return none().release(); \
907 if (policy == return_value_policy::take_ownership) { \
908 auto h = cast(std::move(*src), policy, parent); delete src; return h; \
910 return cast(*src, policy, parent); \
913 operator type*() { return &value; } \
914 operator type&() { return value; } \
915 operator type&&() && { return std::move(value); } \
916 template <typename T_> using cast_op_type = pybind11::detail::movable_cast_op_type<T_>
919 template <typename CharT> using is_std_char_type = any_of<
920 std::is_same<CharT, char>, /* std::string */
921 std::is_same<CharT, char16_t>, /* std::u16string */
922 std::is_same<CharT, char32_t>, /* std::u32string */
923 std::is_same<CharT, wchar_t> /* std::wstring */
926 template <typename T>
927 struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_type<T>::value>> {
928 using _py_type_0 = conditional_t<sizeof(T) <= sizeof(long), long, long long>;
929 using _py_type_1 = conditional_t<std::is_signed<T>::value, _py_type_0, typename std::make_unsigned<_py_type_0>::type>;
930 using py_type = conditional_t<std::is_floating_point<T>::value, double, _py_type_1>;
933 bool load(handle src, bool convert) {
939 if (std::is_floating_point<T>::value) {
940 if (convert || PyFloat_Check(src.ptr()))
941 py_value = (py_type) PyFloat_AsDouble(src.ptr());
944 } else if (PyFloat_Check(src.ptr())) {
946 } else if (std::is_unsigned<py_type>::value) {
947 py_value = as_unsigned<py_type>(src.ptr());
948 } else { // signed integer:
949 py_value = sizeof(T) <= sizeof(long)
950 ? (py_type) PyLong_AsLong(src.ptr())
951 : (py_type) PYBIND11_LONG_AS_LONGLONG(src.ptr());
954 bool py_err = py_value == (py_type) -1 && PyErr_Occurred();
955 if (py_err || (std::is_integral<T>::value && sizeof(py_type) != sizeof(T) &&
956 (py_value < (py_type) std::numeric_limits<T>::min() ||
957 py_value > (py_type) std::numeric_limits<T>::max()))) {
958 bool type_error = py_err && PyErr_ExceptionMatches(
959 #if PY_VERSION_HEX < 0x03000000 && !defined(PYPY_VERSION)
966 if (type_error && convert && PyNumber_Check(src.ptr())) {
967 auto tmp = reinterpret_steal<object>(std::is_floating_point<T>::value
968 ? PyNumber_Float(src.ptr())
969 : PyNumber_Long(src.ptr()));
971 return load(tmp, false);
976 value = (T) py_value;
980 static handle cast(T src, return_value_policy /* policy */, handle /* parent */) {
981 if (std::is_floating_point<T>::value) {
982 return PyFloat_FromDouble((double) src);
983 } else if (sizeof(T) <= sizeof(long)) {
984 if (std::is_signed<T>::value)
985 return PyLong_FromLong((long) src);
987 return PyLong_FromUnsignedLong((unsigned long) src);
989 if (std::is_signed<T>::value)
990 return PyLong_FromLongLong((long long) src);
992 return PyLong_FromUnsignedLongLong((unsigned long long) src);
996 PYBIND11_TYPE_CASTER(T, _<std::is_integral<T>::value>("int", "float"));
999 template<typename T> struct void_caster {
1001 bool load(handle src, bool) {
1002 if (src && src.is_none())
1006 static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
1007 return none().inc_ref();
1009 PYBIND11_TYPE_CASTER(T, _("None"));
1012 template <> class type_caster<void_type> : public void_caster<void_type> {};
1014 template <> class type_caster<void> : public type_caster<void_type> {
1016 using type_caster<void_type>::cast;
1018 bool load(handle h, bool) {
1021 } else if (h.is_none()) {
1026 /* Check if this is a capsule */
1027 if (isinstance<capsule>(h)) {
1028 value = reinterpret_borrow<capsule>(h);
1032 /* Check if this is a C++ type */
1033 auto &bases = all_type_info((PyTypeObject *) h.get_type().ptr());
1034 if (bases.size() == 1) { // Only allowing loading from a single-value type
1035 value = values_and_holders(reinterpret_cast<instance *>(h.ptr())).begin()->value_ptr();
1043 static handle cast(const void *ptr, return_value_policy /* policy */, handle /* parent */) {
1045 return capsule(ptr).release();
1047 return none().inc_ref();
1050 template <typename T> using cast_op_type = void*&;
1051 operator void *&() { return value; }
1052 static PYBIND11_DESCR name() { return type_descr(_("capsule")); }
1054 void *value = nullptr;
1057 template <> class type_caster<std::nullptr_t> : public void_caster<std::nullptr_t> { };
1059 template <> class type_caster<bool> {
1061 bool load(handle src, bool convert) {
1062 if (!src) return false;
1063 else if (src.ptr() == Py_True) { value = true; return true; }
1064 else if (src.ptr() == Py_False) { value = false; return true; }
1065 else if (convert || !strcmp("numpy.bool_", Py_TYPE(src.ptr())->tp_name)) {
1066 // (allow non-implicit conversion for numpy booleans)
1068 Py_ssize_t res = -1;
1069 if (src.is_none()) {
1070 res = 0; // None is implicitly converted to False
1072 #if defined(PYPY_VERSION)
1073 // On PyPy, check that "__bool__" (or "__nonzero__" on Python 2.7) attr exists
1074 else if (hasattr(src, PYBIND11_BOOL_ATTR)) {
1075 res = PyObject_IsTrue(src.ptr());
1078 // Alternate approach for CPython: this does the same as the above, but optimized
1079 // using the CPython API so as to avoid an unneeded attribute lookup.
1080 else if (auto tp_as_number = src.ptr()->ob_type->tp_as_number) {
1081 if (PYBIND11_NB_BOOL(tp_as_number)) {
1082 res = (*PYBIND11_NB_BOOL(tp_as_number))(src.ptr());
1086 if (res == 0 || res == 1) {
1093 static handle cast(bool src, return_value_policy /* policy */, handle /* parent */) {
1094 return handle(src ? Py_True : Py_False).inc_ref();
1096 PYBIND11_TYPE_CASTER(bool, _("bool"));
1099 // Helper class for UTF-{8,16,32} C++ stl strings:
1100 template <typename StringType, bool IsView = false> struct string_caster {
1101 using CharT = typename StringType::value_type;
1103 // Simplify life by being able to assume standard char sizes (the standard only guarantees
1104 // minimums, but Python requires exact sizes)
1105 static_assert(!std::is_same<CharT, char>::value || sizeof(CharT) == 1, "Unsupported char size != 1");
1106 static_assert(!std::is_same<CharT, char16_t>::value || sizeof(CharT) == 2, "Unsupported char16_t size != 2");
1107 static_assert(!std::is_same<CharT, char32_t>::value || sizeof(CharT) == 4, "Unsupported char32_t size != 4");
1108 // wchar_t can be either 16 bits (Windows) or 32 (everywhere else)
1109 static_assert(!std::is_same<CharT, wchar_t>::value || sizeof(CharT) == 2 || sizeof(CharT) == 4,
1110 "Unsupported wchar_t size != 2/4");
1111 static constexpr size_t UTF_N = 8 * sizeof(CharT);
1113 bool load(handle src, bool) {
1114 #if PY_MAJOR_VERSION < 3
1117 handle load_src = src;
1120 } else if (!PyUnicode_Check(load_src.ptr())) {
1121 #if PY_MAJOR_VERSION >= 3
1122 return load_bytes(load_src);
1124 if (sizeof(CharT) == 1) {
1125 return load_bytes(load_src);
1128 // The below is a guaranteed failure in Python 3 when PyUnicode_Check returns false
1129 if (!PYBIND11_BYTES_CHECK(load_src.ptr()))
1132 temp = reinterpret_steal<object>(PyUnicode_FromObject(load_src.ptr()));
1133 if (!temp) { PyErr_Clear(); return false; }
1138 object utfNbytes = reinterpret_steal<object>(PyUnicode_AsEncodedString(
1139 load_src.ptr(), UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr));
1140 if (!utfNbytes) { PyErr_Clear(); return false; }
1142 const CharT *buffer = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
1143 size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
1144 if (UTF_N > 8) { buffer++; length--; } // Skip BOM for UTF-16/32
1145 value = StringType(buffer, length);
1147 // If we're loading a string_view we need to keep the encoded Python object alive:
1149 loader_life_support::add_patient(utfNbytes);
1154 static handle cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {
1155 const char *buffer = reinterpret_cast<const char *>(src.data());
1156 ssize_t nbytes = ssize_t(src.size() * sizeof(CharT));
1157 handle s = decode_utfN(buffer, nbytes);
1158 if (!s) throw error_already_set();
1162 PYBIND11_TYPE_CASTER(StringType, _(PYBIND11_STRING_NAME));
1165 static handle decode_utfN(const char *buffer, ssize_t nbytes) {
1166 #if !defined(PYPY_VERSION)
1168 UTF_N == 8 ? PyUnicode_DecodeUTF8(buffer, nbytes, nullptr) :
1169 UTF_N == 16 ? PyUnicode_DecodeUTF16(buffer, nbytes, nullptr, nullptr) :
1170 PyUnicode_DecodeUTF32(buffer, nbytes, nullptr, nullptr);
1172 // PyPy seems to have multiple problems related to PyUnicode_UTF*: the UTF8 version
1173 // sometimes segfaults for unknown reasons, while the UTF16 and 32 versions require a
1174 // non-const char * arguments, which is also a nuisance, so bypass the whole thing by just
1175 // passing the encoding as a string value, which works properly:
1176 return PyUnicode_Decode(buffer, nbytes, UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr);
1180 // When loading into a std::string or char*, accept a bytes object as-is (i.e.
1181 // without any encoding/decoding attempt). For other C++ char sizes this is a no-op.
1182 // which supports loading a unicode from a str, doesn't take this path.
1183 template <typename C = CharT>
1184 bool load_bytes(enable_if_t<sizeof(C) == 1, handle> src) {
1185 if (PYBIND11_BYTES_CHECK(src.ptr())) {
1186 // We were passed a Python 3 raw bytes; accept it into a std::string or char*
1187 // without any encoding attempt.
1188 const char *bytes = PYBIND11_BYTES_AS_STRING(src.ptr());
1190 value = StringType(bytes, (size_t) PYBIND11_BYTES_SIZE(src.ptr()));
1198 template <typename C = CharT>
1199 bool load_bytes(enable_if_t<sizeof(C) != 1, handle>) { return false; }
1202 template <typename CharT, class Traits, class Allocator>
1203 struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_std_char_type<CharT>::value>>
1204 : string_caster<std::basic_string<CharT, Traits, Allocator>> {};
1206 #ifdef PYBIND11_HAS_STRING_VIEW
1207 template <typename CharT, class Traits>
1208 struct type_caster<std::basic_string_view<CharT, Traits>, enable_if_t<is_std_char_type<CharT>::value>>
1209 : string_caster<std::basic_string_view<CharT, Traits>, true> {};
1212 // Type caster for C-style strings. We basically use a std::string type caster, but also add the
1213 // ability to use None as a nullptr char* (which the string caster doesn't allow).
1214 template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type<CharT>::value>> {
1215 using StringType = std::basic_string<CharT>;
1216 using StringCaster = type_caster<StringType>;
1217 StringCaster str_caster;
1221 bool load(handle src, bool convert) {
1222 if (!src) return false;
1223 if (src.is_none()) {
1224 // Defer accepting None to other overloads (if we aren't in convert mode):
1225 if (!convert) return false;
1229 return str_caster.load(src, convert);
1232 static handle cast(const CharT *src, return_value_policy policy, handle parent) {
1233 if (src == nullptr) return pybind11::none().inc_ref();
1234 return StringCaster::cast(StringType(src), policy, parent);
1237 static handle cast(CharT src, return_value_policy policy, handle parent) {
1238 if (std::is_same<char, CharT>::value) {
1239 handle s = PyUnicode_DecodeLatin1((const char *) &src, 1, nullptr);
1240 if (!s) throw error_already_set();
1243 return StringCaster::cast(StringType(1, src), policy, parent);
1246 operator CharT*() { return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str()); }
1249 throw value_error("Cannot convert None to a character");
1251 auto &value = static_cast<StringType &>(str_caster);
1252 size_t str_len = value.size();
1254 throw value_error("Cannot convert empty string to a character");
1256 // If we're in UTF-8 mode, we have two possible failures: one for a unicode character that
1257 // is too high, and one for multiple unicode characters (caught later), so we need to figure
1258 // out how long the first encoded character is in bytes to distinguish between these two
1259 // errors. We also allow want to allow unicode characters U+0080 through U+00FF, as those
1260 // can fit into a single char value.
1261 if (StringCaster::UTF_N == 8 && str_len > 1 && str_len <= 4) {
1262 unsigned char v0 = static_cast<unsigned char>(value[0]);
1263 size_t char0_bytes = !(v0 & 0x80) ? 1 : // low bits only: 0-127
1264 (v0 & 0xE0) == 0xC0 ? 2 : // 0b110xxxxx - start of 2-byte sequence
1265 (v0 & 0xF0) == 0xE0 ? 3 : // 0b1110xxxx - start of 3-byte sequence
1266 4; // 0b11110xxx - start of 4-byte sequence
1268 if (char0_bytes == str_len) {
1269 // If we have a 128-255 value, we can decode it into a single char:
1270 if (char0_bytes == 2 && (v0 & 0xFC) == 0xC0) { // 0x110000xx 0x10xxxxxx
1271 one_char = static_cast<CharT>(((v0 & 3) << 6) + (static_cast<unsigned char>(value[1]) & 0x3F));
1274 // Otherwise we have a single character, but it's > U+00FF
1275 throw value_error("Character code point not in range(0x100)");
1279 // UTF-16 is much easier: we can only have a surrogate pair for values above U+FFFF, thus a
1280 // surrogate pair with total length 2 instantly indicates a range error (but not a "your
1281 // string was too long" error).
1282 else if (StringCaster::UTF_N == 16 && str_len == 2) {
1283 one_char = static_cast<CharT>(value[0]);
1284 if (one_char >= 0xD800 && one_char < 0xE000)
1285 throw value_error("Character code point not in range(0x10000)");
1289 throw value_error("Expected a character, but multi-character string found");
1291 one_char = value[0];
1295 static PYBIND11_DESCR name() { return type_descr(_(PYBIND11_STRING_NAME)); }
1296 template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>;
1299 // Base implementation for std::tuple and std::pair
1300 template <template<typename...> class Tuple, typename... Ts> class tuple_caster {
1301 using type = Tuple<Ts...>;
1302 static constexpr auto size = sizeof...(Ts);
1303 using indices = make_index_sequence<size>;
1306 bool load(handle src, bool convert) {
1307 if (!isinstance<sequence>(src))
1309 const auto seq = reinterpret_borrow<sequence>(src);
1310 if (seq.size() != size)
1312 return load_impl(seq, convert, indices{});
1315 template <typename T>
1316 static handle cast(T &&src, return_value_policy policy, handle parent) {
1317 return cast_impl(std::forward<T>(src), policy, parent, indices{});
1320 static PYBIND11_DESCR name() {
1321 return type_descr(_("Tuple[") + detail::concat(make_caster<Ts>::name()...) + _("]"));
1324 template <typename T> using cast_op_type = type;
1326 operator type() & { return implicit_cast(indices{}); }
1327 operator type() && { return std::move(*this).implicit_cast(indices{}); }
1330 template <size_t... Is>
1331 type implicit_cast(index_sequence<Is...>) & { return type(cast_op<Ts>(std::get<Is>(subcasters))...); }
1332 template <size_t... Is>
1333 type implicit_cast(index_sequence<Is...>) && { return type(cast_op<Ts>(std::move(std::get<Is>(subcasters)))...); }
1335 static constexpr bool load_impl(const sequence &, bool, index_sequence<>) { return true; }
1337 template <size_t... Is>
1338 bool load_impl(const sequence &seq, bool convert, index_sequence<Is...>) {
1339 for (bool r : {std::get<Is>(subcasters).load(seq[Is], convert)...})
1345 /* Implementation: Convert a C++ tuple into a Python tuple */
1346 template <typename T, size_t... Is>
1347 static handle cast_impl(T &&src, return_value_policy policy, handle parent, index_sequence<Is...>) {
1348 std::array<object, size> entries{{
1349 reinterpret_steal<object>(make_caster<Ts>::cast(std::get<Is>(std::forward<T>(src)), policy, parent))...
1351 for (const auto &entry: entries)
1356 for (auto & entry: entries)
1357 PyTuple_SET_ITEM(result.ptr(), counter++, entry.release().ptr());
1358 return result.release();
1361 Tuple<make_caster<Ts>...> subcasters;
1364 template <typename T1, typename T2> class type_caster<std::pair<T1, T2>>
1365 : public tuple_caster<std::pair, T1, T2> {};
1367 template <typename... Ts> class type_caster<std::tuple<Ts...>>
1368 : public tuple_caster<std::tuple, Ts...> {};
1370 /// Helper class which abstracts away certain actions. Users can provide specializations for
1371 /// custom holders, but it's only necessary if the type has a non-standard interface.
1372 template <typename T>
1373 struct holder_helper {
1374 static auto get(const T &p) -> decltype(p.get()) { return p.get(); }
1377 /// Type caster for holder types like std::shared_ptr, etc.
1378 template <typename type, typename holder_type>
1379 struct copyable_holder_caster : public type_caster_base<type> {
1381 using base = type_caster_base<type>;
1382 static_assert(std::is_base_of<base, type_caster<type>>::value,
1383 "Holder classes are only supported for custom types");
1386 using base::typeinfo;
1389 bool load(handle src, bool convert) {
1390 return base::template load_impl<copyable_holder_caster<type, holder_type>>(src, convert);
1393 explicit operator type*() { return this->value; }
1394 explicit operator type&() { return *(this->value); }
1395 explicit operator holder_type*() { return std::addressof(holder); }
1397 // Workaround for Intel compiler bug
1398 // see pybind11 issue 94
1399 #if defined(__ICC) || defined(__INTEL_COMPILER)
1400 operator holder_type&() { return holder; }
1402 explicit operator holder_type&() { return holder; }
1405 static handle cast(const holder_type &src, return_value_policy, handle) {
1406 const auto *ptr = holder_helper<holder_type>::get(src);
1407 return type_caster_base<type>::cast_holder(ptr, &src);
1411 friend class type_caster_generic;
1412 void check_holder_compat() {
1413 if (typeinfo->default_holder)
1414 throw cast_error("Unable to load a custom holder type from a default-holder instance");
1417 bool load_value(value_and_holder &&v_h) {
1418 if (v_h.holder_constructed()) {
1419 value = v_h.value_ptr();
1420 holder = v_h.template holder<holder_type>();
1423 throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
1425 "(compile in debug mode for type information)");
1427 "of type '" + type_id<holder_type>() + "''");
1432 template <typename T = holder_type, detail::enable_if_t<!std::is_constructible<T, const T &, type*>::value, int> = 0>
1433 bool try_implicit_casts(handle, bool) { return false; }
1435 template <typename T = holder_type, detail::enable_if_t<std::is_constructible<T, const T &, type*>::value, int> = 0>
1436 bool try_implicit_casts(handle src, bool convert) {
1437 for (auto &cast : typeinfo->implicit_casts) {
1438 copyable_holder_caster sub_caster(*cast.first);
1439 if (sub_caster.load(src, convert)) {
1440 value = cast.second(sub_caster.value);
1441 holder = holder_type(sub_caster.holder, (type *) value);
1448 static bool try_direct_conversions(handle) { return false; }
1454 /// Specialize for the common std::shared_ptr, so users don't need to
1455 template <typename T>
1456 class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::shared_ptr<T>> { };
1458 template <typename type, typename holder_type>
1459 struct move_only_holder_caster {
1460 static_assert(std::is_base_of<type_caster_base<type>, type_caster<type>>::value,
1461 "Holder classes are only supported for custom types");
1463 static handle cast(holder_type &&src, return_value_policy, handle) {
1464 auto *ptr = holder_helper<holder_type>::get(src);
1465 return type_caster_base<type>::cast_holder(ptr, std::addressof(src));
1467 static PYBIND11_DESCR name() { return type_caster_base<type>::name(); }
1470 template <typename type, typename deleter>
1471 class type_caster<std::unique_ptr<type, deleter>>
1472 : public move_only_holder_caster<type, std::unique_ptr<type, deleter>> { };
1474 template <typename type, typename holder_type>
1475 using type_caster_holder = conditional_t<is_copy_constructible<holder_type>::value,
1476 copyable_holder_caster<type, holder_type>,
1477 move_only_holder_caster<type, holder_type>>;
1479 template <typename T, bool Value = false> struct always_construct_holder { static constexpr bool value = Value; };
1481 /// Create a specialization for custom holder types (silently ignores std::shared_ptr)
1482 #define PYBIND11_DECLARE_HOLDER_TYPE(type, holder_type, ...) \
1483 namespace pybind11 { namespace detail { \
1484 template <typename type> \
1485 struct always_construct_holder<holder_type> : always_construct_holder<void, ##__VA_ARGS__> { }; \
1486 template <typename type> \
1487 class type_caster<holder_type, enable_if_t<!is_shared_ptr<holder_type>::value>> \
1488 : public type_caster_holder<type, holder_type> { }; \
1491 // PYBIND11_DECLARE_HOLDER_TYPE holder types:
1492 template <typename base, typename holder> struct is_holder_type :
1493 std::is_base_of<detail::type_caster_holder<base, holder>, detail::type_caster<holder>> {};
1494 // Specialization for always-supported unique_ptr holders:
1495 template <typename base, typename deleter> struct is_holder_type<base, std::unique_ptr<base, deleter>> :
1498 template <typename T> struct handle_type_name { static PYBIND11_DESCR name() { return _<T>(); } };
1499 template <> struct handle_type_name<bytes> { static PYBIND11_DESCR name() { return _(PYBIND11_BYTES_NAME); } };
1500 template <> struct handle_type_name<args> { static PYBIND11_DESCR name() { return _("*args"); } };
1501 template <> struct handle_type_name<kwargs> { static PYBIND11_DESCR name() { return _("**kwargs"); } };
1503 template <typename type>
1504 struct pyobject_caster {
1505 template <typename T = type, enable_if_t<std::is_same<T, handle>::value, int> = 0>
1506 bool load(handle src, bool /* convert */) { value = src; return static_cast<bool>(value); }
1508 template <typename T = type, enable_if_t<std::is_base_of<object, T>::value, int> = 0>
1509 bool load(handle src, bool /* convert */) {
1510 if (!isinstance<type>(src))
1512 value = reinterpret_borrow<type>(src);
1516 static handle cast(const handle &src, return_value_policy /* policy */, handle /* parent */) {
1517 return src.inc_ref();
1519 PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name());
1522 template <typename T>
1523 class type_caster<T, enable_if_t<is_pyobject<T>::value>> : public pyobject_caster<T> { };
1525 // Our conditions for enabling moving are quite restrictive:
1527 // - T needs to be a non-const, non-pointer, non-reference type
1528 // - type_caster<T>::operator T&() must exist
1529 // - the type must be move constructible (obviously)
1531 // - if the type is non-copy-constructible, the object must be the sole owner of the type (i.e. it
1532 // must have ref_count() == 1)h
1533 // If any of the above are not satisfied, we fall back to copying.
1534 template <typename T> using move_is_plain_type = satisfies_none_of<T,
1535 std::is_void, std::is_pointer, std::is_reference, std::is_const
1537 template <typename T, typename SFINAE = void> struct move_always : std::false_type {};
1538 template <typename T> struct move_always<T, enable_if_t<all_of<
1539 move_is_plain_type<T>,
1540 negation<is_copy_constructible<T>>,
1541 std::is_move_constructible<T>,
1542 std::is_same<decltype(std::declval<make_caster<T>>().operator T&()), T&>
1543 >::value>> : std::true_type {};
1544 template <typename T, typename SFINAE = void> struct move_if_unreferenced : std::false_type {};
1545 template <typename T> struct move_if_unreferenced<T, enable_if_t<all_of<
1546 move_is_plain_type<T>,
1547 negation<move_always<T>>,
1548 std::is_move_constructible<T>,
1549 std::is_same<decltype(std::declval<make_caster<T>>().operator T&()), T&>
1550 >::value>> : std::true_type {};
1551 template <typename T> using move_never = none_of<move_always<T>, move_if_unreferenced<T>>;
1553 // Detect whether returning a `type` from a cast on type's type_caster is going to result in a
1554 // reference or pointer to a local variable of the type_caster. Basically, only
1555 // non-reference/pointer `type`s and reference/pointers from a type_caster_generic are safe;
1556 // everything else returns a reference/pointer to a local variable.
1557 template <typename type> using cast_is_temporary_value_reference = bool_constant<
1558 (std::is_reference<type>::value || std::is_pointer<type>::value) &&
1559 !std::is_base_of<type_caster_generic, make_caster<type>>::value
1562 // When a value returned from a C++ function is being cast back to Python, we almost always want to
1563 // force `policy = move`, regardless of the return value policy the function/method was declared
1565 template <typename Return, typename SFINAE = void> struct return_value_policy_override {
1566 static return_value_policy policy(return_value_policy p) { return p; }
1569 template <typename Return> struct return_value_policy_override<Return,
1570 detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>> {
1571 static return_value_policy policy(return_value_policy p) {
1572 return !std::is_lvalue_reference<Return>::value && !std::is_pointer<Return>::value
1573 ? return_value_policy::move : p;
1577 // Basic python -> C++ casting; throws if casting fails
1578 template <typename T, typename SFINAE> type_caster<T, SFINAE> &load_type(type_caster<T, SFINAE> &conv, const handle &handle) {
1579 if (!conv.load(handle, true)) {
1581 throw cast_error("Unable to cast Python instance to C++ type (compile in debug mode for details)");
1583 throw cast_error("Unable to cast Python instance of type " +
1584 (std::string) str(handle.get_type()) + " to C++ type '" + type_id<T>() + "'");
1589 // Wrapper around the above that also constructs and returns a type_caster
1590 template <typename T> make_caster<T> load_type(const handle &handle) {
1591 make_caster<T> conv;
1592 load_type(conv, handle);
1596 NAMESPACE_END(detail)
1598 // pytype -> C++ type
1599 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
1600 T cast(const handle &handle) {
1601 using namespace detail;
1602 static_assert(!cast_is_temporary_value_reference<T>::value,
1603 "Unable to cast type to reference: value is local to type caster");
1604 return cast_op<T>(load_type<T>(handle));
1607 // pytype -> pytype (calls converting constructor)
1608 template <typename T, detail::enable_if_t<detail::is_pyobject<T>::value, int> = 0>
1609 T cast(const handle &handle) { return T(reinterpret_borrow<object>(handle)); }
1611 // C++ type -> py::object
1612 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
1613 object cast(const T &value, return_value_policy policy = return_value_policy::automatic_reference,
1614 handle parent = handle()) {
1615 if (policy == return_value_policy::automatic)
1616 policy = std::is_pointer<T>::value ? return_value_policy::take_ownership : return_value_policy::copy;
1617 else if (policy == return_value_policy::automatic_reference)
1618 policy = std::is_pointer<T>::value ? return_value_policy::reference : return_value_policy::copy;
1619 return reinterpret_steal<object>(detail::make_caster<T>::cast(value, policy, parent));
1622 template <typename T> T handle::cast() const { return pybind11::cast<T>(*this); }
1623 template <> inline void handle::cast() const { return; }
1625 template <typename T>
1626 detail::enable_if_t<!detail::move_never<T>::value, T> move(object &&obj) {
1627 if (obj.ref_count() > 1)
1629 throw cast_error("Unable to cast Python instance to C++ rvalue: instance has multiple references"
1630 " (compile in debug mode for details)");
1632 throw cast_error("Unable to move from Python " + (std::string) str(obj.get_type()) +
1633 " instance to C++ " + type_id<T>() + " instance: instance has multiple references");
1636 // Move into a temporary and return that, because the reference may be a local value of `conv`
1637 T ret = std::move(detail::load_type<T>(obj).operator T&());
1641 // Calling cast() on an rvalue calls pybind::cast with the object rvalue, which does:
1642 // - If we have to move (because T has no copy constructor), do it. This will fail if the moved
1643 // object has multiple references, but trying to copy will fail to compile.
1644 // - If both movable and copyable, check ref count: if 1, move; otherwise copy
1645 // - Otherwise (not movable), copy.
1646 template <typename T> detail::enable_if_t<detail::move_always<T>::value, T> cast(object &&object) {
1647 return move<T>(std::move(object));
1649 template <typename T> detail::enable_if_t<detail::move_if_unreferenced<T>::value, T> cast(object &&object) {
1650 if (object.ref_count() > 1)
1651 return cast<T>(object);
1653 return move<T>(std::move(object));
1655 template <typename T> detail::enable_if_t<detail::move_never<T>::value, T> cast(object &&object) {
1656 return cast<T>(object);
1659 template <typename T> T object::cast() const & { return pybind11::cast<T>(*this); }
1660 template <typename T> T object::cast() && { return pybind11::cast<T>(std::move(*this)); }
1661 template <> inline void object::cast() const & { return; }
1662 template <> inline void object::cast() && { return; }
1664 NAMESPACE_BEGIN(detail)
1666 // Declared in pytypes.h:
1667 template <typename T, enable_if_t<!is_pyobject<T>::value, int>>
1668 object object_or_cast(T &&o) { return pybind11::cast(std::forward<T>(o)); }
1670 struct overload_unused {}; // Placeholder type for the unneeded (and dead code) static variable in the OVERLOAD_INT macro
1671 template <typename ret_type> using overload_caster_t = conditional_t<
1672 cast_is_temporary_value_reference<ret_type>::value, make_caster<ret_type>, overload_unused>;
1674 // Trampoline use: for reference/pointer types to value-converted values, we do a value cast, then
1675 // store the result in the given variable. For other types, this is a no-op.
1676 template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&o, make_caster<T> &caster) {
1677 return cast_op<T>(load_type(caster, o));
1679 template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&, overload_unused &) {
1680 pybind11_fail("Internal error: cast_ref fallback invoked"); }
1682 // Trampoline use: Having a pybind11::cast with an invalid reference type is going to static_assert, even
1683 // though if it's in dead code, so we provide a "trampoline" to pybind11::cast that only does anything in
1684 // cases where pybind11::cast is valid.
1685 template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_safe(object &&o) {
1686 return pybind11::cast<T>(std::move(o)); }
1687 template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_safe(object &&) {
1688 pybind11_fail("Internal error: cast_safe fallback invoked"); }
1689 template <> inline void cast_safe<void>(object &&) {}
1691 NAMESPACE_END(detail)
1693 template <return_value_policy policy = return_value_policy::automatic_reference>
1694 tuple make_tuple() { return tuple(0); }
1696 template <return_value_policy policy = return_value_policy::automatic_reference,
1697 typename... Args> tuple make_tuple(Args&&... args_) {
1698 constexpr size_t size = sizeof...(Args);
1699 std::array<object, size> args {
1700 { reinterpret_steal<object>(detail::make_caster<Args>::cast(
1701 std::forward<Args>(args_), policy, nullptr))... }
1703 for (size_t i = 0; i < args.size(); i++) {
1706 throw cast_error("make_tuple(): unable to convert arguments to Python object (compile in debug mode for details)");
1708 std::array<std::string, size> argtypes { {type_id<Args>()...} };
1709 throw cast_error("make_tuple(): unable to convert argument of type '" +
1710 argtypes[i] + "' to Python object");
1716 for (auto &arg_value : args)
1717 PyTuple_SET_ITEM(result.ptr(), counter++, arg_value.release().ptr());
1721 /// \ingroup annotations
1722 /// Annotation for arguments
1724 /// Constructs an argument with the name of the argument; if null or omitted, this is a positional argument.
1725 constexpr explicit arg(const char *name = nullptr) : name(name), flag_noconvert(false), flag_none(true) { }
1726 /// Assign a value to this argument
1727 template <typename T> arg_v operator=(T &&value) const;
1728 /// Indicate that the type should not be converted in the type caster
1729 arg &noconvert(bool flag = true) { flag_noconvert = flag; return *this; }
1730 /// Indicates that the argument should/shouldn't allow None (e.g. for nullable pointer args)
1731 arg &none(bool flag = true) { flag_none = flag; return *this; }
1733 const char *name; ///< If non-null, this is a named kwargs argument
1734 bool flag_noconvert : 1; ///< If set, do not allow conversion (requires a supporting type caster!)
1735 bool flag_none : 1; ///< If set (the default), allow None to be passed to this argument
1738 /// \ingroup annotations
1739 /// Annotation for arguments with values
1740 struct arg_v : arg {
1742 template <typename T>
1743 arg_v(arg &&base, T &&x, const char *descr = nullptr)
1745 value(reinterpret_steal<object>(
1746 detail::make_caster<T>::cast(x, return_value_policy::automatic, {})
1749 #if !defined(NDEBUG)
1750 , type(type_id<T>())
1755 /// Direct construction with name, default, and description
1756 template <typename T>
1757 arg_v(const char *name, T &&x, const char *descr = nullptr)
1758 : arg_v(arg(name), std::forward<T>(x), descr) { }
1760 /// Called internally when invoking `py::arg("a") = value`
1761 template <typename T>
1762 arg_v(const arg &base, T &&x, const char *descr = nullptr)
1763 : arg_v(arg(base), std::forward<T>(x), descr) { }
1765 /// Same as `arg::noconvert()`, but returns *this as arg_v&, not arg&
1766 arg_v &noconvert(bool flag = true) { arg::noconvert(flag); return *this; }
1768 /// Same as `arg::nonone()`, but returns *this as arg_v&, not arg&
1769 arg_v &none(bool flag = true) { arg::none(flag); return *this; }
1771 /// The default value
1773 /// The (optional) description of the default value
1775 #if !defined(NDEBUG)
1776 /// The C++ type name of the default value (only available when compiled in debug mode)
1781 template <typename T>
1782 arg_v arg::operator=(T &&value) const { return {std::move(*this), std::forward<T>(value)}; }
1784 /// Alias for backward compatibility -- to be removed in version 2.0
1785 template <typename /*unused*/> using arg_t = arg_v;
1787 inline namespace literals {
1789 String literal version of `arg`
1791 constexpr arg operator"" _a(const char *name, size_t) { return arg(name); }
1794 NAMESPACE_BEGIN(detail)
1796 // forward declaration (definition in attr.h)
1797 struct function_record;
1799 /// Internal data associated with a single function call
1800 struct function_call {
1801 function_call(function_record &f, handle p); // Implementation in attr.h
1803 /// The function data:
1804 const function_record &func;
1806 /// Arguments passed to the function:
1807 std::vector<handle> args;
1809 /// The `convert` value the arguments should be loaded with
1810 std::vector<bool> args_convert;
1812 /// Extra references for the optional `py::args` and/or `py::kwargs` arguments (which, if
1813 /// present, are also in `args` but without a reference).
1814 object args_ref, kwargs_ref;
1816 /// The parent, if any
1819 /// If this is a call to an initializer, this argument contains `self`
1824 /// Helper class which loads arguments for C++ functions called from Python
1825 template <typename... Args>
1826 class argument_loader {
1827 using indices = make_index_sequence<sizeof...(Args)>;
1829 template <typename Arg> using argument_is_args = std::is_same<intrinsic_t<Arg>, args>;
1830 template <typename Arg> using argument_is_kwargs = std::is_same<intrinsic_t<Arg>, kwargs>;
1831 // Get args/kwargs argument positions relative to the end of the argument list:
1832 static constexpr auto args_pos = constexpr_first<argument_is_args, Args...>() - (int) sizeof...(Args),
1833 kwargs_pos = constexpr_first<argument_is_kwargs, Args...>() - (int) sizeof...(Args);
1835 static constexpr bool args_kwargs_are_last = kwargs_pos >= - 1 && args_pos >= kwargs_pos - 1;
1837 static_assert(args_kwargs_are_last, "py::args/py::kwargs are only permitted as the last argument(s) of a function");
1840 static constexpr bool has_kwargs = kwargs_pos < 0;
1841 static constexpr bool has_args = args_pos < 0;
1843 static PYBIND11_DESCR arg_names() { return detail::concat(make_caster<Args>::name()...); }
1845 bool load_args(function_call &call) {
1846 return load_impl_sequence(call, indices{});
1849 template <typename Return, typename Guard, typename Func>
1850 enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) && {
1851 return std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
1854 template <typename Return, typename Guard, typename Func>
1855 enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) && {
1856 std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
1862 static bool load_impl_sequence(function_call &, index_sequence<>) { return true; }
1864 template <size_t... Is>
1865 bool load_impl_sequence(function_call &call, index_sequence<Is...>) {
1866 for (bool r : {std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])...})
1872 template <typename Return, typename Func, size_t... Is, typename Guard>
1873 Return call_impl(Func &&f, index_sequence<Is...>, Guard &&) {
1874 return std::forward<Func>(f)(cast_op<Args>(std::move(std::get<Is>(argcasters)))...);
1877 std::tuple<make_caster<Args>...> argcasters;
1880 /// Helper class which collects only positional arguments for a Python function call.
1881 /// A fancier version below can collect any argument, but this one is optimal for simple calls.
1882 template <return_value_policy policy>
1883 class simple_collector {
1885 template <typename... Ts>
1886 explicit simple_collector(Ts &&...values)
1887 : m_args(pybind11::make_tuple<policy>(std::forward<Ts>(values)...)) { }
1889 const tuple &args() const & { return m_args; }
1890 dict kwargs() const { return {}; }
1892 tuple args() && { return std::move(m_args); }
1894 /// Call a Python function and pass the collected arguments
1895 object call(PyObject *ptr) const {
1896 PyObject *result = PyObject_CallObject(ptr, m_args.ptr());
1898 throw error_already_set();
1899 return reinterpret_steal<object>(result);
1906 /// Helper class which collects positional, keyword, * and ** arguments for a Python function call
1907 template <return_value_policy policy>
1908 class unpacking_collector {
1910 template <typename... Ts>
1911 explicit unpacking_collector(Ts &&...values) {
1912 // Tuples aren't (easily) resizable so a list is needed for collection,
1913 // but the actual function call strictly requires a tuple.
1914 auto args_list = list();
1915 int _[] = { 0, (process(args_list, std::forward<Ts>(values)), 0)... };
1918 m_args = std::move(args_list);
1921 const tuple &args() const & { return m_args; }
1922 const dict &kwargs() const & { return m_kwargs; }
1924 tuple args() && { return std::move(m_args); }
1925 dict kwargs() && { return std::move(m_kwargs); }
1927 /// Call a Python function and pass the collected arguments
1928 object call(PyObject *ptr) const {
1929 PyObject *result = PyObject_Call(ptr, m_args.ptr(), m_kwargs.ptr());
1931 throw error_already_set();
1932 return reinterpret_steal<object>(result);
1936 template <typename T>
1937 void process(list &args_list, T &&x) {
1938 auto o = reinterpret_steal<object>(detail::make_caster<T>::cast(std::forward<T>(x), policy, {}));
1941 argument_cast_error();
1943 argument_cast_error(std::to_string(args_list.size()), type_id<T>());
1946 args_list.append(o);
1949 void process(list &args_list, detail::args_proxy ap) {
1950 for (const auto &a : ap)
1951 args_list.append(a);
1954 void process(list &/*args_list*/, arg_v a) {
1957 nameless_argument_error();
1959 nameless_argument_error(a.type);
1962 if (m_kwargs.contains(a.name)) {
1964 multiple_values_error();
1966 multiple_values_error(a.name);
1971 argument_cast_error();
1973 argument_cast_error(a.name, a.type);
1976 m_kwargs[a.name] = a.value;
1979 void process(list &/*args_list*/, detail::kwargs_proxy kp) {
1982 for (const auto &k : reinterpret_borrow<dict>(kp)) {
1983 if (m_kwargs.contains(k.first)) {
1985 multiple_values_error();
1987 multiple_values_error(str(k.first));
1990 m_kwargs[k.first] = k.second;
1994 [[noreturn]] static void nameless_argument_error() {
1995 throw type_error("Got kwargs without a name; only named arguments "
1996 "may be passed via py::arg() to a python function call. "
1997 "(compile in debug mode for details)");
1999 [[noreturn]] static void nameless_argument_error(std::string type) {
2000 throw type_error("Got kwargs without a name of type '" + type + "'; only named "
2001 "arguments may be passed via py::arg() to a python function call. ");
2003 [[noreturn]] static void multiple_values_error() {
2004 throw type_error("Got multiple values for keyword argument "
2005 "(compile in debug mode for details)");
2008 [[noreturn]] static void multiple_values_error(std::string name) {
2009 throw type_error("Got multiple values for keyword argument '" + name + "'");
2012 [[noreturn]] static void argument_cast_error() {
2013 throw cast_error("Unable to convert call argument to Python object "
2014 "(compile in debug mode for details)");
2017 [[noreturn]] static void argument_cast_error(std::string name, std::string type) {
2018 throw cast_error("Unable to convert call argument '" + name
2019 + "' of type '" + type + "' to Python object");
2027 /// Collect only positional arguments for a Python function call
2028 template <return_value_policy policy, typename... Args,
2029 typename = enable_if_t<all_of<is_positional<Args>...>::value>>
2030 simple_collector<policy> collect_arguments(Args &&...args) {
2031 return simple_collector<policy>(std::forward<Args>(args)...);
2034 /// Collect all arguments, including keywords and unpacking (only instantiated when needed)
2035 template <return_value_policy policy, typename... Args,
2036 typename = enable_if_t<!all_of<is_positional<Args>...>::value>>
2037 unpacking_collector<policy> collect_arguments(Args &&...args) {
2038 // Following argument order rules for generalized unpacking according to PEP 448
2040 constexpr_last<is_positional, Args...>() < constexpr_first<is_keyword_or_ds, Args...>()
2041 && constexpr_last<is_s_unpacking, Args...>() < constexpr_first<is_ds_unpacking, Args...>(),
2042 "Invalid function call: positional args must precede keywords and ** unpacking; "
2043 "* unpacking must precede ** unpacking"
2045 return unpacking_collector<policy>(std::forward<Args>(args)...);
2048 template <typename Derived>
2049 template <return_value_policy policy, typename... Args>
2050 object object_api<Derived>::operator()(Args &&...args) const {
2051 return detail::collect_arguments<policy>(std::forward<Args>(args)...).call(derived().ptr());
2054 template <typename Derived>
2055 template <return_value_policy policy, typename... Args>
2056 object object_api<Derived>::call(Args &&...args) const {
2057 return operator()<policy>(std::forward<Args>(args)...);
2060 NAMESPACE_END(detail)
2062 #define PYBIND11_MAKE_OPAQUE(Type) \
2063 namespace pybind11 { namespace detail { \
2064 template<> class type_caster<Type> : public type_caster_base<Type> { }; \
2067 NAMESPACE_END(PYBIND11_NAMESPACE)