387 lines
16 KiB
ReStructuredText
387 lines
16 KiB
ReStructuredText
.. highlightlang:: 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, increment the reference count of 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 :const:`Py_PRINT_RAW`; if given, the :func:`str` of the object is written
|
|
instead of the :func:`repr`.
|
|
|
|
|
|
.. 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.
|
|
|
|
|
|
.. c:function:: int PyObject_HasAttrString(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)``. This function
|
|
always succeeds.
|
|
|
|
|
|
.. 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``.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_GetAttrString(PyObject *o, const char *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``.
|
|
|
|
|
|
.. 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:`__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*. Returns ``-1`` on failure. This is the equivalent of the Python statement
|
|
``o.attr_name = v``.
|
|
|
|
|
|
.. c:function:: int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)
|
|
|
|
Set the value of the attribute named *attr_name*, for object *o*, to the value
|
|
*v*. Returns ``-1`` on failure. This is the equivalent of the Python statement
|
|
``o.attr_name = v``.
|
|
|
|
|
|
.. c:function:: int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)
|
|
|
|
Generic attribute setter function that is meant to be put into a type
|
|
object's ``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 the attribute in the instance dictionary. Otherwise, the
|
|
attribute is set in the object's :attr:`__dict__` (if present). 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)
|
|
|
|
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:: PyObject* PyType_GenericGetDict(PyObject *o, void *context)
|
|
|
|
A generic implementation for the getter of a ``__dict__`` descriptor. It
|
|
creates the dictionary if necessary.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
|
|
.. c:function:: int PyType_GenericSetDict(PyObject *o, 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_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 :const:`Py_LT`, :const:`Py_LE`, :const:`Py_EQ`,
|
|
:const:`Py_NE`, :const:`Py_GT`, or :const:`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 :const:`Py_LT`, :const:`Py_LE`, :const:`Py_EQ`,
|
|
:const:`Py_NE`, :const:`Py_GT`, or :const:`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 :const:`Py_EQ` and ``0`` for :const:`Py_NE`.
|
|
|
|
.. c:function:: PyObject* PyObject_Repr(PyObject *o)
|
|
|
|
.. index:: builtin: 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.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_ASCII(PyObject *o)
|
|
|
|
.. index:: builtin: 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.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Str(PyObject *o)
|
|
|
|
.. index:: builtin: str
|
|
|
|
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.
|
|
|
|
.. c:function:: PyObject* PyObject_Bytes(PyObject *o)
|
|
|
|
.. index:: builtin: 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_IsInstance(PyObject *inst, PyObject *cls)
|
|
|
|
Returns ``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 type object rather than a class object, :c:func:`PyObject_IsInstance`
|
|
returns ``1`` if *inst* is of type *cls*. 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 *inst* is not a
|
|
class instance and *cls* is neither a type object, nor a class object, nor a
|
|
tuple, *inst* must have a :attr:`__class__` attribute --- the class relationship
|
|
of the value of that attribute with *cls* will be used to determine the result
|
|
of this function.
|
|
|
|
|
|
Subclass determination is done in a fairly straightforward way, but includes a
|
|
wrinkle that implementors of extensions to the class system may want to be aware
|
|
of. If :class:`A` and :class:`B` are class objects, :class:`B` is a subclass of
|
|
:class:`A` if it inherits from :class:`A` either directly or indirectly. If
|
|
either is not a class object, a more general mechanism is used to determine the
|
|
class relationship of the two objects. When testing if *B* is a subclass of
|
|
*A*, if *A* is *B*, :c:func:`PyObject_IsSubclass` returns true. If *A* and *B*
|
|
are different objects, *B*'s :attr:`__bases__` attribute is searched in a
|
|
depth-first fashion for *A* --- the presence of the :attr:`__bases__` attribute
|
|
is considered sufficient for this determination.
|
|
|
|
|
|
.. c:function:: int PyObject_IsSubclass(PyObject *derived, PyObject *cls)
|
|
|
|
Returns ``1`` if the class *derived* is identical to or derived from the class
|
|
*cls*, otherwise returns ``0``. In case of an error, returns ``-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 either *derived* or *cls* is not an actual class object (or tuple),
|
|
this function uses the generic algorithm described above.
|
|
|
|
|
|
.. c:function:: int PyCallable_Check(PyObject *o)
|
|
|
|
Determine if the object *o* is callable. Return ``1`` if the object is callable
|
|
and ``0`` otherwise. This function always succeeds.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_Call(PyObject *callable_object, PyObject *args, PyObject *kw)
|
|
|
|
Call a callable Python object *callable_object*, with arguments given by the
|
|
tuple *args*, and named arguments given by the dictionary *kw*. If no named
|
|
arguments are needed, *kw* may be *NULL*. *args* must not be *NULL*, use an
|
|
empty tuple if no arguments are needed. Returns the result of the call on
|
|
success, or *NULL* on failure. This is the equivalent of the Python expression
|
|
``callable_object(*args, **kw)``.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_CallObject(PyObject *callable_object, PyObject *args)
|
|
|
|
Call a callable Python object *callable_object*, with arguments given by the
|
|
tuple *args*. If no arguments are needed, then *args* may be *NULL*. Returns
|
|
the result of the call on success, or *NULL* on failure. This is the equivalent
|
|
of the Python expression ``callable_object(*args)``.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_CallFunction(PyObject *callable, char *format, ...)
|
|
|
|
Call a callable Python object *callable*, with a variable number of C arguments.
|
|
The C arguments are described using a :c:func:`Py_BuildValue` style format
|
|
string. The format may be *NULL*, indicating that no arguments are provided.
|
|
Returns the result of the call on success, or *NULL* on failure. This is the
|
|
equivalent of the Python expression ``callable(*args)``. Note that if you only
|
|
pass :c:type:`PyObject \*` args, :c:func:`PyObject_CallFunctionObjArgs` is a
|
|
faster alternative.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_CallMethod(PyObject *o, char *method, char *format, ...)
|
|
|
|
Call the method named *method* of object *o* with a variable number of C
|
|
arguments. The C arguments are described by a :c:func:`Py_BuildValue` format
|
|
string that should produce a tuple. The format may be *NULL*, indicating that
|
|
no arguments are provided. Returns the result of the call on success, or *NULL*
|
|
on failure. This is the equivalent of the Python expression ``o.method(args)``.
|
|
Note that if you only pass :c:type:`PyObject \*` args,
|
|
:c:func:`PyObject_CallMethodObjArgs` is a faster alternative.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_CallFunctionObjArgs(PyObject *callable, ..., NULL)
|
|
|
|
Call a callable Python object *callable*, with a variable number of
|
|
:c:type:`PyObject\*` arguments. The arguments are provided as a variable number
|
|
of parameters followed by *NULL*. Returns the result of the call on success, or
|
|
*NULL* on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyObject_CallMethodObjArgs(PyObject *o, PyObject *name, ..., NULL)
|
|
|
|
Calls a method of the object *o*, where the name of the method is given as a
|
|
Python string object in *name*. It is called with a variable number of
|
|
:c:type:`PyObject\*` arguments. The arguments are provided as a variable number
|
|
of parameters followed by *NULL*. Returns the result of the call on success, or
|
|
*NULL* on failure.
|
|
|
|
|
|
.. c:function:: Py_hash_t PyObject_Hash(PyObject *o)
|
|
|
|
.. index:: builtin: 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 Py_ssize_t.
|
|
|
|
|
|
.. c:function:: Py_hash_t PyObject_HashNotImplemented(PyObject *o)
|
|
|
|
Set a :exc:`TypeError` indicating that ``type(o)`` is not 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:: builtin: 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 increments the
|
|
reference count of the return value. There's really no reason to use this
|
|
function instead of the common expression ``o->ob_type``, which returns a
|
|
pointer of type :c:type:`PyTypeObject\*`, except when the incremented reference
|
|
count is needed.
|
|
|
|
|
|
.. c:function:: int PyObject_TypeCheck(PyObject *o, PyTypeObject *type)
|
|
|
|
Return true if the object *o* is of type *type* or a subtype of *type*. Both
|
|
parameters must be non-*NULL*.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyObject_Length(PyObject *o)
|
|
Py_ssize_t PyObject_Size(PyObject *o)
|
|
|
|
.. index:: builtin: 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 default)
|
|
|
|
Return an estimated length for the object *o*. First trying to return its
|
|
actual length, then an estimate using ``__length_hint__``, and finally
|
|
returning the default value. On error ``-1`` is returned. This is the
|
|
equivalent to the Python expression ``operator.length_hint(o, default)``.
|
|
|
|
.. 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*. Returns ``-1`` on failure. This is the
|
|
equivalent of the Python statement ``o[key] = v``.
|
|
|
|
|
|
.. c:function:: int PyObject_DelItem(PyObject *o, PyObject *key)
|
|
|
|
Delete the mapping for *key* from *o*. Returns ``-1`` on failure. This is the
|
|
equivalent of 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.
|