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In order to fully satisfy Python's inheritance type layout requirements, all types should have a common 'solid' base. A solid base is one which has the same instance size as the derived type (not counting the space required for the optional `dict_ptr` and `weakrefs_ptr`). Thus, `object` does not qualify as a solid base for pybind11 types and this can lead to issues with multiple inheritance. To get around this, new base types are created: one per unique instance size. There is going to be very few of these bases. They ensure Python's MRO checks will pass when multiple bases are involved.
124 lines
3.8 KiB
C++
124 lines
3.8 KiB
C++
/*
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tests/test_inheritance.cpp -- inheritance, automatic upcasting for polymorphic types
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Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
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All rights reserved. Use of this source code is governed by a
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BSD-style license that can be found in the LICENSE file.
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*/
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#include "pybind11_tests.h"
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class Pet {
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public:
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Pet(const std::string &name, const std::string &species)
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: m_name(name), m_species(species) {}
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std::string name() const { return m_name; }
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std::string species() const { return m_species; }
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private:
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std::string m_name;
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std::string m_species;
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};
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class Dog : public Pet {
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public:
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Dog(const std::string &name) : Pet(name, "dog") {}
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std::string bark() const { return "Woof!"; }
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};
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class Rabbit : public Pet {
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public:
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Rabbit(const std::string &name) : Pet(name, "parrot") {}
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};
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class Hamster : public Pet {
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public:
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Hamster(const std::string &name) : Pet(name, "rodent") {}
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};
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class Chimera : public Pet {
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Chimera() : Pet("Kimmy", "chimera") {}
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};
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std::string pet_name_species(const Pet &pet) {
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return pet.name() + " is a " + pet.species();
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}
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std::string dog_bark(const Dog &dog) {
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return dog.bark();
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}
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struct BaseClass { virtual ~BaseClass() {} };
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struct DerivedClass1 : BaseClass { };
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struct DerivedClass2 : BaseClass { };
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struct MismatchBase1 { };
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struct MismatchDerived1 : MismatchBase1 { };
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struct MismatchBase2 { };
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struct MismatchDerived2 : MismatchBase2 { };
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test_initializer inheritance([](py::module &m) {
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py::class_<Pet> pet_class(m, "Pet");
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pet_class
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.def(py::init<std::string, std::string>())
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.def("name", &Pet::name)
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.def("species", &Pet::species);
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/* One way of declaring a subclass relationship: reference parent's class_ object */
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py::class_<Dog>(m, "Dog", pet_class)
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.def(py::init<std::string>());
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/* Another way of declaring a subclass relationship: reference parent's C++ type */
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py::class_<Rabbit, Pet>(m, "Rabbit")
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.def(py::init<std::string>());
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/* And another: list parent in class template arguments */
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py::class_<Hamster, Pet>(m, "Hamster")
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.def(py::init<std::string>());
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py::class_<Chimera, Pet>(m, "Chimera");
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m.def("pet_name_species", pet_name_species);
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m.def("dog_bark", dog_bark);
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py::class_<BaseClass>(m, "BaseClass").def(py::init<>());
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py::class_<DerivedClass1>(m, "DerivedClass1").def(py::init<>());
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py::class_<DerivedClass2>(m, "DerivedClass2").def(py::init<>());
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m.def("return_class_1", []() -> BaseClass* { return new DerivedClass1(); });
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m.def("return_class_2", []() -> BaseClass* { return new DerivedClass2(); });
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m.def("return_class_n", [](int n) -> BaseClass* {
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if (n == 1) return new DerivedClass1();
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if (n == 2) return new DerivedClass2();
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return new BaseClass();
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});
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m.def("return_none", []() -> BaseClass* { return nullptr; });
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m.def("test_isinstance", [](py::list l) {
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struct Unregistered { }; // checks missing type_info code path
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return py::make_tuple(
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py::isinstance<py::tuple>(l[0]),
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py::isinstance<py::dict>(l[1]),
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py::isinstance<Pet>(l[2]),
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py::isinstance<Pet>(l[3]),
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py::isinstance<Dog>(l[4]),
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py::isinstance<Rabbit>(l[5]),
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py::isinstance<Unregistered>(l[6])
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);
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});
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m.def("test_mismatched_holder_type_1", []() {
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auto m = py::module::import("__main__");
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py::class_<MismatchBase1, std::shared_ptr<MismatchBase1>>(m, "MismatchBase1");
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py::class_<MismatchDerived1, MismatchBase1>(m, "MismatchDerived1");
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});
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m.def("test_mismatched_holder_type_2", []() {
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auto m = py::module::import("__main__");
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py::class_<MismatchBase2>(m, "MismatchBase2");
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py::class_<MismatchDerived2, std::shared_ptr<MismatchDerived2>, MismatchBase2>(m, "MismatchDerived2");
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});
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});
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