Method clone

tests/test_class_sh_trampoline_unique_ptr.cpp:41–43

class PyClass : public Class, public py::trampoline_self_life_support {
public:
    std::unique_ptr<Class> clone() const override {
        PYBIND11_OVERRIDE_PURE(std::unique_ptr<Class>, Class, clone);
    }

    int foo() const override { PYBIND11_OVERRIDE_PURE(int, Class, foo); }
};