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