cpython/Doc/library/types.rst

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:mod:`types` --- Names for built-in types
=========================================
.. module:: types
:synopsis: Names for built-in types.
**Source code:** :source:`Lib/types.py`
--------------
This module defines names for some object types that are used by the standard
Python interpreter, but not exposed as builtins like :class:`int` or
:class:`str` are. Also, it does not include some of the types that arise
transparently during processing such as the ``listiterator`` type.
Typical use is for :func:`isinstance` or :func:`issubclass` checks.
The module defines the following names:
.. data:: FunctionType
LambdaType
The type of user-defined functions and functions created by :keyword:`lambda`
expressions.
.. data:: GeneratorType
The type of :term:`generator`-iterator objects, produced by calling a
generator function.
.. data:: CodeType
.. index:: builtin: compile
The type for code objects such as returned by :func:`compile`.
.. data:: MethodType
The type of methods of user-defined class instances.
.. data:: BuiltinFunctionType
BuiltinMethodType
The type of built-in functions like :func:`len` or :func:`sys.exit`, and
methods of built-in classes. (Here, the term "built-in" means "written in
C".)
.. data:: ModuleType
The type of modules.
.. data:: TracebackType
The type of traceback objects such as found in ``sys.exc_info()[2]``.
.. data:: FrameType
The type of frame objects such as found in ``tb.tb_frame`` if ``tb`` is a
traceback object.
.. data:: GetSetDescriptorType
The type of objects defined in extension modules with ``PyGetSetDef``, such
as ``FrameType.f_locals`` or ``array.array.typecode``. This type is used as
descriptor for object attributes; it has the same purpose as the
:class:`property` type, but for classes defined in extension modules.
.. data:: MemberDescriptorType
The type of objects defined in extension modules with ``PyMemberDef``, such
as ``datetime.timedelta.days``. This type is used as descriptor for simple C
data members which use standard conversion functions; it has the same purpose
as the :class:`property` type, but for classes defined in extension modules.
.. impl-detail::
In other implementations of Python, this type may be identical to
``GetSetDescriptorType``.
.. class:: MappingProxyType(mapping)
Read-only proxy of a mapping. It provides a dynamic view on the mapping's
entries, which means that when the mapping changes, the view reflects these
changes.
.. versionadded:: 3.3
.. describe:: key in proxy
Return ``True`` if the underlying mapping has a key *key*, else
``False``.
.. describe:: proxy[key]
Return the item of the underlying mapping with key *key*. Raises a
:exc:`KeyError` if *key* is not in the underlying mapping.
.. describe:: iter(proxy)
Return an iterator over the keys of the underlying mapping. This is a
shortcut for ``iter(proxy.keys())``.
.. describe:: len(proxy)
Return the number of items in the underlying mapping.
.. method:: copy()
Return a shallow copy of the underlying mapping.
.. method:: get(key[, default])
Return the value for *key* if *key* is in the underlying mapping, else
*default*. If *default* is not given, it defaults to ``None``, so that
this method never raises a :exc:`KeyError`.
.. method:: items()
Return a new view of the underlying mapping's items (``(key, value)``
pairs).
.. method:: keys()
Return a new view of the underlying mapping's keys.
.. method:: values()
Return a new view of the underlying mapping's values.