feat: py::type::of<T>() and py::type::of(h) (#2364)
* feat: type<T>()
* refactor: using py::type as class
* refactor: py::object as base
* wip: tigher api
* refactor: fix conversion and limit API further
* docs: some added notes from @EricCousineau-TRI
* refactor: use py::type::of
diff --git a/docs/advanced/cast/index.rst b/docs/advanced/cast/index.rst
index 724585c..3ce9ea0 100644
--- a/docs/advanced/cast/index.rst
+++ b/docs/advanced/cast/index.rst
@@ -1,3 +1,5 @@
+.. _type-conversions:
+
Type conversions
################
diff --git a/docs/advanced/classes.rst b/docs/advanced/classes.rst
index f4efc68..b91e8a1 100644
--- a/docs/advanced/classes.rst
+++ b/docs/advanced/classes.rst
@@ -1232,3 +1232,21 @@
more complete example, including a demonstration of how to provide
automatic downcasting for an entire class hierarchy without
writing one get() function for each class.
+
+Accessing the type object
+=========================
+
+You can get the type object from a C++ class that has already been registered using:
+
+.. code-block:: python
+
+ py::type T_py = py::type::of<T>();
+
+You can directly use ``py::type::of(ob)`` to get the type object from any python
+object, just like ``type(ob)`` in Python.
+
+.. note::
+
+ Other types, like ``py::type::of<int>()``, do not work, see :ref:`type-conversions`.
+
+.. versionadded:: 2.6
diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index be62610..5601f2e 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -2204,6 +2204,18 @@
PYBIND11_NAMESPACE_END(detail)
+
+template<typename T>
+type type::of() {
+ static_assert(
+ std::is_base_of<detail::type_caster_generic, detail::make_caster<T>>::value,
+ "py::type::of<T> only supports the case where T is a registered C++ types."
+ );
+
+ return type((PyObject*) detail::get_type_handle(typeid(T), true).ptr(), borrowed_t());
+}
+
+
#define PYBIND11_MAKE_OPAQUE(...) \
namespace pybind11 { namespace detail { \
template<> class type_caster<__VA_ARGS__> : public type_caster_base<__VA_ARGS__> { }; \
diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index 00c791a..c1219fc 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -19,6 +19,7 @@
/* A few forward declarations */
class handle; class object;
class str; class iterator;
+class type;
struct arg; struct arg_v;
PYBIND11_NAMESPACE_BEGIN(detail)
@@ -890,6 +891,21 @@
object value = {};
};
+
+
+class type : public object {
+public:
+ PYBIND11_OBJECT(type, object, PyType_Check)
+
+ static type of(handle h) { return type((PyObject*) Py_TYPE(h.ptr()), borrowed_t{}); }
+
+ /// Convert C++ type to py::type if previously registered. Does not convert
+ // standard types, like int, float. etc. yet.
+ // See https://github.com/pybind/pybind11/issues/2486
+ template<typename T>
+ static type of();
+};
+
class iterable : public object {
public:
PYBIND11_OBJECT_DEFAULT(iterable, object, detail::PyIterable_Check)
diff --git a/tests/test_class.cpp b/tests/test_class.cpp
index 5369cb0..b7d52a1 100644
--- a/tests/test_class.cpp
+++ b/tests/test_class.cpp
@@ -134,6 +134,32 @@
);
});
+ struct Invalid {};
+
+ // test_type
+ m.def("check_type", [](int category) {
+ // Currently not supported (via a fail at compile time)
+ // See https://github.com/pybind/pybind11/issues/2486
+ // if (category == 2)
+ // return py::type::of<int>();
+ if (category == 1)
+ return py::type::of<DerivedClass1>();
+ else
+ return py::type::of<Invalid>();
+ });
+
+ m.def("get_type_of", [](py::object ob) {
+ return py::type::of(ob);
+ });
+
+ m.def("as_type", [](py::object ob) {
+ auto tp = py::type(ob);
+ if (py::isinstance<py::type>(ob))
+ return tp;
+ else
+ throw std::runtime_error("Invalid type");
+ });
+
// test_mismatched_holder
struct MismatchBase1 { };
struct MismatchDerived1 : MismatchBase1 { };
diff --git a/tests/test_class.py b/tests/test_class.py
index 4214fe7..be21f37 100644
--- a/tests/test_class.py
+++ b/tests/test_class.py
@@ -26,6 +26,40 @@
assert cstats.alive() == 0
+def test_type():
+ assert m.check_type(1) == m.DerivedClass1
+ with pytest.raises(RuntimeError) as execinfo:
+ m.check_type(0)
+
+ assert 'pybind11::detail::get_type_info: unable to find type info' in str(execinfo.value)
+ assert 'Invalid' in str(execinfo.value)
+
+ # Currently not supported
+ # See https://github.com/pybind/pybind11/issues/2486
+ # assert m.check_type(2) == int
+
+
+def test_type_of_py():
+ assert m.get_type_of(1) == int
+ assert m.get_type_of(m.DerivedClass1()) == m.DerivedClass1
+ assert m.get_type_of(int) == type
+
+
+def test_type_of_py_nodelete():
+ # If the above test deleted the class, this will segfault
+ assert m.get_type_of(m.DerivedClass1()) == m.DerivedClass1
+
+
+def test_as_type_py():
+ assert m.as_type(int) == int
+
+ with pytest.raises(RuntimeError):
+ assert m.as_type(1) == int
+
+ with pytest.raises(RuntimeError):
+ assert m.as_type(m.DerivedClass1()) == m.DerivedClass1
+
+
def test_docstrings(doc):
assert doc(UserType) == "A `py::class_` type for testing"
assert UserType.__name__ == "UserType"