| .. highlight:: c |
| |
| .. _typehintobjects: |
| |
| Objects for Type Hinting |
| ------------------------ |
| |
| Various built-in types for type hinting are provided. Currently, |
| two types exist -- :ref:`GenericAlias <types-genericalias>` and |
| :ref:`Union <types-union>`. Only ``GenericAlias`` is exposed to C. |
| |
| .. c:function:: PyObject* Py_GenericAlias(PyObject *origin, PyObject *args) |
| |
| Create a :ref:`GenericAlias <types-genericalias>` object. |
| Equivalent to calling the Python class |
| :class:`types.GenericAlias`. The *origin* and *args* arguments set the |
| ``GenericAlias``\ 's ``__origin__`` and ``__args__`` attributes respectively. |
| *origin* should be a :c:type:`PyTypeObject*`, and *args* can be a |
| :c:type:`PyTupleObject*` or any ``PyObject*``. If *args* passed is |
| not a tuple, a 1-tuple is automatically constructed and ``__args__`` is set |
| to ``(args,)``. |
| Minimal checking is done for the arguments, so the function will succeed even |
| if *origin* is not a type. |
| The ``GenericAlias``\ 's ``__parameters__`` attribute is constructed lazily |
| from ``__args__``. On failure, an exception is raised and ``NULL`` is |
| returned. |
| |
| Here's an example of how to make an extension type generic:: |
| |
| ... |
| static PyMethodDef my_obj_methods[] = { |
| // Other methods. |
| ... |
| {"__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS, "See PEP 585"} |
| ... |
| } |
| |
| .. seealso:: The data model method :meth:`__class_getitem__`. |
| |
| .. versionadded:: 3.9 |
| |
| .. c:var:: PyTypeObject Py_GenericAliasType |
| |
| The C type of the object returned by :c:func:`Py_GenericAlias`. Equivalent to |
| :class:`types.GenericAlias` in Python. |
| |
| .. versionadded:: 3.9 |