mirror of https://github.com/python/cpython
510 lines
20 KiB
ReStructuredText
510 lines
20 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _object:
|
|
|
|
Object Protocol
|
|
===============
|
|
|
|
|
|
.. c:var:: PyObject* Py_NotImplemented
|
|
|
|
The ``NotImplemented`` singleton, used to signal that an operation is
|
|
not implemented for the given type combination.
|
|
|
|
|
|
.. c:macro:: Py_RETURN_NOTIMPLEMENTED
|
|
|
|
Properly handle returning :c:data:`Py_NotImplemented` from within a C
|
|
function (that is, create a new :term:`strong reference`
|
|
to NotImplemented and return it).
|
|
|
|
|
|
.. c:function:: int PyObject_Print(PyObject *o, FILE *fp, int flags)
|
|
|
|
Print an object *o*, on file *fp*. Returns ``-1`` on error. The flags argument
|
|
is used to enable certain printing options. The only option currently supported
|
|
is :c:macro:`Py_PRINT_RAW`; if given, the :func:`str` of the object is written
|
|
instead of the :func:`repr`.
|
|
|
|
|
|
.. c:function:: int PyObject_HasAttrWithError(PyObject *o, const char *attr_name)
|
|
|
|
Returns ``1`` if *o* has the attribute *attr_name*, and ``0`` otherwise.
|
|
This is equivalent to the Python expression ``hasattr(o, attr_name)``.
|
|
On failure, return ``-1``.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: int PyObject_HasAttrStringWithError(PyObject *o, const char *attr_name)
|
|
|
|
This is the same as :c:func:`PyObject_HasAttrWithError`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: int PyObject_HasAttr(PyObject *o, PyObject *attr_name)
|
|
|
|
Returns ``1`` if *o* has the attribute *attr_name*, and ``0`` otherwise. This
|
|
is equivalent to the Python expression ``hasattr(o, attr_name)``. This function
|
|
always succeeds.
|
|
|
|
.. note::
|
|
|
|
Exceptions that occur when this calls :meth:`~object.__getattr__` and
|
|
:meth:`~object.__getattribute__` methods are silently ignored.
|
|
For proper error handling, use :c:func:`PyObject_HasAttrWithError`,
|
|
:c:func:`PyObject_GetOptionalAttr` or :c:func:`PyObject_GetAttr` instead.
|
|
|
|
|
|
.. c:function:: int PyObject_HasAttrString(PyObject *o, const char *attr_name)
|
|
|
|
This is the same as :c:func:`PyObject_HasAttr`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
.. note::
|
|
|
|
Exceptions that occur when this calls :meth:`~object.__getattr__` and
|
|
:meth:`~object.__getattribute__` methods or while creating the temporary
|
|
:class:`str` object are silently ignored.
|
|
For proper error handling, use :c:func:`PyObject_HasAttrStringWithError`,
|
|
:c:func:`PyObject_GetOptionalAttrString`
|
|
or :c:func:`PyObject_GetAttrString` instead.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetAttr(PyObject *o, PyObject *attr_name)
|
|
|
|
Retrieve an attribute named *attr_name* from object *o*. Returns the attribute
|
|
value on success, or ``NULL`` on failure. This is the equivalent of the Python
|
|
expression ``o.attr_name``.
|
|
|
|
If the missing attribute should not be treated as a failure, you can use
|
|
:c:func:`PyObject_GetOptionalAttr` instead.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetAttrString(PyObject *o, const char *attr_name)
|
|
|
|
This is the same as :c:func:`PyObject_GetAttr`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
If the missing attribute should not be treated as a failure, you can use
|
|
:c:func:`PyObject_GetOptionalAttrString` instead.
|
|
|
|
|
|
.. c:function:: int PyObject_GetOptionalAttr(PyObject *obj, PyObject *attr_name, PyObject **result);
|
|
|
|
Variant of :c:func:`PyObject_GetAttr` which doesn't raise
|
|
:exc:`AttributeError` if the attribute is not found.
|
|
|
|
If the attribute is found, return ``1`` and set *\*result* to a new
|
|
:term:`strong reference` to the attribute.
|
|
If the attribute is not found, return ``0`` and set *\*result* to ``NULL``;
|
|
the :exc:`AttributeError` is silenced.
|
|
If an error other than :exc:`AttributeError` is raised, return ``-1`` and
|
|
set *\*result* to ``NULL``.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
|
|
.. c:function:: int PyObject_GetOptionalAttrString(PyObject *obj, const char *attr_name, PyObject **result);
|
|
|
|
This is the same as :c:func:`PyObject_GetOptionalAttr`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. c:function:: PyObject* PyObject_GenericGetAttr(PyObject *o, PyObject *name)
|
|
|
|
Generic attribute getter function that is meant to be put into a type
|
|
object's ``tp_getattro`` slot. It looks for a descriptor in the dictionary
|
|
of classes in the object's MRO as well as an attribute in the object's
|
|
:attr:`~object.__dict__` (if present). As outlined in :ref:`descriptors`,
|
|
data descriptors take preference over instance attributes, while non-data
|
|
descriptors don't. Otherwise, an :exc:`AttributeError` is raised.
|
|
|
|
|
|
.. c:function:: int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v)
|
|
|
|
Set the value of the attribute named *attr_name*, for object *o*, to the value
|
|
*v*. Raise an exception and return ``-1`` on failure;
|
|
return ``0`` on success. This is the equivalent of the Python statement
|
|
``o.attr_name = v``.
|
|
|
|
If *v* is ``NULL``, the attribute is deleted. This behaviour is deprecated
|
|
in favour of using :c:func:`PyObject_DelAttr`, but there are currently no
|
|
plans to remove it.
|
|
|
|
|
|
.. c:function:: int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)
|
|
|
|
This is the same as :c:func:`PyObject_SetAttr`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
If *v* is ``NULL``, the attribute is deleted, but this feature is
|
|
deprecated in favour of using :c:func:`PyObject_DelAttrString`.
|
|
|
|
|
|
.. c:function:: int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)
|
|
|
|
Generic attribute setter and deleter function that is meant
|
|
to be put into a type object's :c:member:`~PyTypeObject.tp_setattro`
|
|
slot. It looks for a data descriptor in the
|
|
dictionary of classes in the object's MRO, and if found it takes preference
|
|
over setting or deleting the attribute in the instance dictionary. Otherwise, the
|
|
attribute is set or deleted in the object's :attr:`~object.__dict__` (if present).
|
|
On success, ``0`` is returned, otherwise an :exc:`AttributeError`
|
|
is raised and ``-1`` is returned.
|
|
|
|
|
|
.. c:function:: int PyObject_DelAttr(PyObject *o, PyObject *attr_name)
|
|
|
|
Delete attribute named *attr_name*, for object *o*. Returns ``-1`` on failure.
|
|
This is the equivalent of the Python statement ``del o.attr_name``.
|
|
|
|
|
|
.. c:function:: int PyObject_DelAttrString(PyObject *o, const char *attr_name)
|
|
|
|
This is the same as :c:func:`PyObject_DelAttr`, but *attr_name* is
|
|
specified as a :c:expr:`const char*` UTF-8 encoded bytes string,
|
|
rather than a :c:expr:`PyObject*`.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GenericGetDict(PyObject *o, void *context)
|
|
|
|
A generic implementation for the getter of a ``__dict__`` descriptor. It
|
|
creates the dictionary if necessary.
|
|
|
|
This function may also be called to get the :py:attr:`~object.__dict__`
|
|
of the object *o*. Pass ``NULL`` for *context* when calling it.
|
|
Since this function may need to allocate memory for the
|
|
dictionary, it may be more efficient to call :c:func:`PyObject_GetAttr`
|
|
when accessing an attribute on the object.
|
|
|
|
On failure, returns ``NULL`` with an exception set.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
|
|
.. c:function:: int PyObject_GenericSetDict(PyObject *o, PyObject *value, void *context)
|
|
|
|
A generic implementation for the setter of a ``__dict__`` descriptor. This
|
|
implementation does not allow the dictionary to be deleted.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
|
|
.. c:function:: PyObject** _PyObject_GetDictPtr(PyObject *obj)
|
|
|
|
Return a pointer to :py:attr:`~object.__dict__` of the object *obj*.
|
|
If there is no ``__dict__``, return ``NULL`` without setting an exception.
|
|
|
|
This function may need to allocate memory for the
|
|
dictionary, so it may be more efficient to call :c:func:`PyObject_GetAttr`
|
|
when accessing an attribute on the object.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_RichCompare(PyObject *o1, PyObject *o2, int opid)
|
|
|
|
Compare the values of *o1* and *o2* using the operation specified by *opid*,
|
|
which must be one of :c:macro:`Py_LT`, :c:macro:`Py_LE`, :c:macro:`Py_EQ`,
|
|
:c:macro:`Py_NE`, :c:macro:`Py_GT`, or :c:macro:`Py_GE`, corresponding to ``<``,
|
|
``<=``, ``==``, ``!=``, ``>``, or ``>=`` respectively. This is the equivalent of
|
|
the Python expression ``o1 op o2``, where ``op`` is the operator corresponding
|
|
to *opid*. Returns the value of the comparison on success, or ``NULL`` on failure.
|
|
|
|
|
|
.. c:function:: int PyObject_RichCompareBool(PyObject *o1, PyObject *o2, int opid)
|
|
|
|
Compare the values of *o1* and *o2* using the operation specified by *opid*,
|
|
which must be one of :c:macro:`Py_LT`, :c:macro:`Py_LE`, :c:macro:`Py_EQ`,
|
|
:c:macro:`Py_NE`, :c:macro:`Py_GT`, or :c:macro:`Py_GE`, corresponding to ``<``,
|
|
``<=``, ``==``, ``!=``, ``>``, or ``>=`` respectively. Returns ``-1`` on error,
|
|
``0`` if the result is false, ``1`` otherwise. This is the equivalent of the
|
|
Python expression ``o1 op o2``, where ``op`` is the operator corresponding to
|
|
*opid*.
|
|
|
|
.. note::
|
|
If *o1* and *o2* are the same object, :c:func:`PyObject_RichCompareBool`
|
|
will always return ``1`` for :c:macro:`Py_EQ` and ``0`` for :c:macro:`Py_NE`.
|
|
|
|
.. c:function:: PyObject* PyObject_Format(PyObject *obj, PyObject *format_spec)
|
|
|
|
Format *obj* using *format_spec*. This is equivalent to the Python
|
|
expression ``format(obj, format_spec)``.
|
|
|
|
*format_spec* may be ``NULL``. In this case the call is equivalent
|
|
to ``format(obj)``.
|
|
Returns the formatted string on success, ``NULL`` on failure.
|
|
|
|
.. c:function:: PyObject* PyObject_Repr(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; repr
|
|
|
|
Compute a string representation of object *o*. Returns the string
|
|
representation on success, ``NULL`` on failure. This is the equivalent of the
|
|
Python expression ``repr(o)``. Called by the :func:`repr` built-in function.
|
|
|
|
.. versionchanged:: 3.4
|
|
This function now includes a debug assertion to help ensure that it
|
|
does not silently discard an active exception.
|
|
|
|
.. c:function:: PyObject* PyObject_ASCII(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; ascii
|
|
|
|
As :c:func:`PyObject_Repr`, compute a string representation of object *o*, but
|
|
escape the non-ASCII characters in the string returned by
|
|
:c:func:`PyObject_Repr` with ``\x``, ``\u`` or ``\U`` escapes. This generates
|
|
a string similar to that returned by :c:func:`PyObject_Repr` in Python 2.
|
|
Called by the :func:`ascii` built-in function.
|
|
|
|
.. index:: string; PyObject_Str (C function)
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Str(PyObject *o)
|
|
|
|
Compute a string representation of object *o*. Returns the string
|
|
representation on success, ``NULL`` on failure. This is the equivalent of the
|
|
Python expression ``str(o)``. Called by the :func:`str` built-in function
|
|
and, therefore, by the :func:`print` function.
|
|
|
|
.. versionchanged:: 3.4
|
|
This function now includes a debug assertion to help ensure that it
|
|
does not silently discard an active exception.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Bytes(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; bytes
|
|
|
|
Compute a bytes representation of object *o*. ``NULL`` is returned on
|
|
failure and a bytes object on success. This is equivalent to the Python
|
|
expression ``bytes(o)``, when *o* is not an integer. Unlike ``bytes(o)``,
|
|
a TypeError is raised when *o* is an integer instead of a zero-initialized
|
|
bytes object.
|
|
|
|
|
|
.. c:function:: int PyObject_IsSubclass(PyObject *derived, PyObject *cls)
|
|
|
|
Return ``1`` if the class *derived* is identical to or derived from the class
|
|
*cls*, otherwise return ``0``. In case of an error, return ``-1``.
|
|
|
|
If *cls* is a tuple, the check will be done against every entry in *cls*.
|
|
The result will be ``1`` when at least one of the checks returns ``1``,
|
|
otherwise it will be ``0``.
|
|
|
|
If *cls* has a :meth:`~class.__subclasscheck__` method, it will be called to
|
|
determine the subclass status as described in :pep:`3119`. Otherwise,
|
|
*derived* is a subclass of *cls* if it is a direct or indirect subclass,
|
|
i.e. contained in ``cls.__mro__``.
|
|
|
|
Normally only class objects, i.e. instances of :class:`type` or a derived
|
|
class, are considered classes. However, objects can override this by having
|
|
a :attr:`~class.__bases__` attribute (which must be a tuple of base classes).
|
|
|
|
|
|
.. c:function:: int PyObject_IsInstance(PyObject *inst, PyObject *cls)
|
|
|
|
Return ``1`` if *inst* is an instance of the class *cls* or a subclass of
|
|
*cls*, or ``0`` if not. On error, returns ``-1`` and sets an exception.
|
|
|
|
If *cls* is a tuple, the check will be done against every entry in *cls*.
|
|
The result will be ``1`` when at least one of the checks returns ``1``,
|
|
otherwise it will be ``0``.
|
|
|
|
If *cls* has a :meth:`~class.__instancecheck__` method, it will be called to
|
|
determine the subclass status as described in :pep:`3119`. Otherwise, *inst*
|
|
is an instance of *cls* if its class is a subclass of *cls*.
|
|
|
|
An instance *inst* can override what is considered its class by having a
|
|
:attr:`~instance.__class__` attribute.
|
|
|
|
An object *cls* can override if it is considered a class, and what its base
|
|
classes are, by having a :attr:`~class.__bases__` attribute (which must be a tuple
|
|
of base classes).
|
|
|
|
|
|
.. c:function:: Py_hash_t PyObject_Hash(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; hash
|
|
|
|
Compute and return the hash value of an object *o*. On failure, return ``-1``.
|
|
This is the equivalent of the Python expression ``hash(o)``.
|
|
|
|
.. versionchanged:: 3.2
|
|
The return type is now Py_hash_t. This is a signed integer the same size
|
|
as :c:type:`Py_ssize_t`.
|
|
|
|
|
|
.. c:function:: Py_hash_t PyObject_HashNotImplemented(PyObject *o)
|
|
|
|
Set a :exc:`TypeError` indicating that ``type(o)`` is not :term:`hashable` and return ``-1``.
|
|
This function receives special treatment when stored in a ``tp_hash`` slot,
|
|
allowing a type to explicitly indicate to the interpreter that it is not
|
|
hashable.
|
|
|
|
|
|
.. c:function:: int PyObject_IsTrue(PyObject *o)
|
|
|
|
Returns ``1`` if the object *o* is considered to be true, and ``0`` otherwise.
|
|
This is equivalent to the Python expression ``not not o``. On failure, return
|
|
``-1``.
|
|
|
|
|
|
.. c:function:: int PyObject_Not(PyObject *o)
|
|
|
|
Returns ``0`` if the object *o* is considered to be true, and ``1`` otherwise.
|
|
This is equivalent to the Python expression ``not o``. On failure, return
|
|
``-1``.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Type(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; type
|
|
|
|
When *o* is non-``NULL``, returns a type object corresponding to the object type
|
|
of object *o*. On failure, raises :exc:`SystemError` and returns ``NULL``. This
|
|
is equivalent to the Python expression ``type(o)``.
|
|
This function creates a new :term:`strong reference` to the return value.
|
|
There's really no reason to use this
|
|
function instead of the :c:func:`Py_TYPE()` function, which returns a
|
|
pointer of type :c:expr:`PyTypeObject*`, except when a new
|
|
:term:`strong reference` is needed.
|
|
|
|
|
|
.. c:function:: int PyObject_TypeCheck(PyObject *o, PyTypeObject *type)
|
|
|
|
Return non-zero if the object *o* is of type *type* or a subtype of *type*, and
|
|
``0`` otherwise. Both parameters must be non-``NULL``.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyObject_Size(PyObject *o)
|
|
Py_ssize_t PyObject_Length(PyObject *o)
|
|
|
|
.. index:: pair: built-in function; len
|
|
|
|
Return the length of object *o*. If the object *o* provides either the sequence
|
|
and mapping protocols, the sequence length is returned. On error, ``-1`` is
|
|
returned. This is the equivalent to the Python expression ``len(o)``.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyObject_LengthHint(PyObject *o, Py_ssize_t defaultvalue)
|
|
|
|
Return an estimated length for the object *o*. First try to return its
|
|
actual length, then an estimate using :meth:`~object.__length_hint__`, and
|
|
finally return the default value. On error return ``-1``. This is the
|
|
equivalent to the Python expression ``operator.length_hint(o, defaultvalue)``.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetItem(PyObject *o, PyObject *key)
|
|
|
|
Return element of *o* corresponding to the object *key* or ``NULL`` on failure.
|
|
This is the equivalent of the Python expression ``o[key]``.
|
|
|
|
|
|
.. c:function:: int PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v)
|
|
|
|
Map the object *key* to the value *v*. Raise an exception and
|
|
return ``-1`` on failure; return ``0`` on success. This is the
|
|
equivalent of the Python statement ``o[key] = v``. This function *does
|
|
not* steal a reference to *v*.
|
|
|
|
|
|
.. c:function:: int PyObject_DelItem(PyObject *o, PyObject *key)
|
|
|
|
Remove the mapping for the object *key* from the object *o*. Return ``-1``
|
|
on failure. This is equivalent to the Python statement ``del o[key]``.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Dir(PyObject *o)
|
|
|
|
This is equivalent to the Python expression ``dir(o)``, returning a (possibly
|
|
empty) list of strings appropriate for the object argument, or ``NULL`` if there
|
|
was an error. If the argument is ``NULL``, this is like the Python ``dir()``,
|
|
returning the names of the current locals; in this case, if no execution frame
|
|
is active then ``NULL`` is returned but :c:func:`PyErr_Occurred` will return false.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetIter(PyObject *o)
|
|
|
|
This is equivalent to the Python expression ``iter(o)``. It returns a new
|
|
iterator for the object argument, or the object itself if the object is already
|
|
an iterator. Raises :exc:`TypeError` and returns ``NULL`` if the object cannot be
|
|
iterated.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetAIter(PyObject *o)
|
|
|
|
This is the equivalent to the Python expression ``aiter(o)``. Takes an
|
|
:class:`AsyncIterable` object and returns an :class:`AsyncIterator` for it.
|
|
This is typically a new iterator but if the argument is an
|
|
:class:`AsyncIterator`, this returns itself. Raises :exc:`TypeError` and
|
|
returns ``NULL`` if the object cannot be iterated.
|
|
|
|
.. versionadded:: 3.10
|
|
|
|
.. c:function:: void *PyObject_GetTypeData(PyObject *o, PyTypeObject *cls)
|
|
|
|
Get a pointer to subclass-specific data reserved for *cls*.
|
|
|
|
The object *o* must be an instance of *cls*, and *cls* must have been
|
|
created using negative :c:member:`PyType_Spec.basicsize`.
|
|
Python does not check this.
|
|
|
|
On error, set an exception and return ``NULL``.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
.. c:function:: Py_ssize_t PyType_GetTypeDataSize(PyTypeObject *cls)
|
|
|
|
Return the size of the instance memory space reserved for *cls*, i.e. the size of the
|
|
memory :c:func:`PyObject_GetTypeData` returns.
|
|
|
|
This may be larger than requested using :c:member:`-PyType_Spec.basicsize <PyType_Spec.basicsize>`;
|
|
it is safe to use this larger size (e.g. with :c:func:`!memset`).
|
|
|
|
The type *cls* **must** have been created using
|
|
negative :c:member:`PyType_Spec.basicsize`.
|
|
Python does not check this.
|
|
|
|
On error, set an exception and return a negative value.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
.. c:function:: void *PyObject_GetItemData(PyObject *o)
|
|
|
|
Get a pointer to per-item data for a class with
|
|
:c:macro:`Py_TPFLAGS_ITEMS_AT_END`.
|
|
|
|
On error, set an exception and return ``NULL``.
|
|
:py:exc:`TypeError` is raised if *o* does not have
|
|
:c:macro:`Py_TPFLAGS_ITEMS_AT_END` set.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
.. c:function:: int PyObject_VisitManagedDict(PyObject *obj, visitproc visit, void *arg)
|
|
|
|
Visit the managed dictionary of *obj*.
|
|
|
|
This function must only be called in a traverse function of the type which
|
|
has the :c:macro:`Py_TPFLAGS_MANAGED_DICT` flag set.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. c:function:: void PyObject_ClearManagedDict(PyObject *obj)
|
|
|
|
Clear the managed dictionary of *obj*.
|
|
|
|
This function must only be called in a traverse function of the type which
|
|
has the :c:macro:`Py_TPFLAGS_MANAGED_DICT` flag set.
|
|
|
|
.. versionadded:: 3.13
|