Object Protocol¶

PyObject *Py_GetConstant(unsigned int constant_id)¶

Part of the Stable ABI since version 3.13.

Set an exception and return NULL if constant_id is invalid.

constant_id must be one of these constant identifiers:

Constant Identifier	Value	Returned object
Py_CONSTANT_NONE¶	`0`	`None`
Py_CONSTANT_FALSE¶	`1`	`False`
Py_CONSTANT_TRUE¶	`2`	`True`
Py_CONSTANT_ELLIPSIS¶	`3`	`Ellipsis`
Py_CONSTANT_NOT_IMPLEMENTED¶	`4`	`NotImplemented`
Py_CONSTANT_ZERO¶	`5`	`0`
Py_CONSTANT_ONE¶	`6`	`1`
Py_CONSTANT_EMPTY_STR¶	`7`	`''`
Py_CONSTANT_EMPTY_BYTES¶	`8`	`b''`
Py_CONSTANT_EMPTY_TUPLE¶	`9`	`()`

Numeric values are only given for projects which cannot use the constant identifiers.

Added in version 3.13.

CPython implementation detail: In CPython, all of these constants are immortal.

PyObject *Py_GetConstantBorrowed(unsigned int constant_id)¶

Part of the Stable ABI since version 3.13.

Similar to Py_GetConstant(), but return a borrowed reference.

This function is primarily intended for backwards compatibility: using Py_GetConstant() is recommended for new code.

The reference is borrowed from the interpreter, and is valid until the interpreter finalization.

Added in version 3.13.

PyObject *Py_NotImplemented¶: The NotImplemented singleton, used to signal that an operation is not implemented for the given type combination.

Py_RETURN_NOTIMPLEMENTED¶: Properly handle returning Py_NotImplemented from within a C function (that is, create a new strong reference to NotImplemented and return it).

Py_PRINT_RAW¶: Flag to be used with multiple functions that print the object (like PyObject_Print() and PyFile_WriteObject()). If passed, these functions use the str() of the object instead of the repr().

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 Py_PRINT_RAW; if given, the str() of the object is written instead of the repr().

int PyObject_HasAttrWithError(PyObject *o, PyObject *attr_name)¶: Part of the Stable ABI since version 3.13.
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.

Added in version 3.13.

int PyObject_HasAttrStringWithError(PyObject *o, const char *attr_name)¶: Part of the Stable ABI since version 3.13.
This is the same as PyObject_HasAttrWithError(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

Added in version 3.13.

int PyObject_HasAttr(PyObject *o, PyObject *attr_name)¶: Part of the Stable ABI.
Returns 1 if o has the attribute attr_name, and 0 otherwise. This function always succeeds.

Note

Exceptions that occur when this calls __getattr__() and __getattribute__() methods aren’t propagated, but instead given to sys.unraisablehook(). For proper error handling, use PyObject_HasAttrWithError(), PyObject_GetOptionalAttr() or PyObject_GetAttr() instead.

int PyObject_HasAttrString(PyObject *o, const char *attr_name)¶: Part of the Stable ABI.
This is the same as PyObject_HasAttr(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

Note

Exceptions that occur when this calls __getattr__() and __getattribute__() methods or while creating the temporary str object are silently ignored. For proper error handling, use PyObject_HasAttrStringWithError(), PyObject_GetOptionalAttrString() or PyObject_GetAttrString() instead.

PyObject *PyObject_GetAttr(PyObject *o, PyObject *attr_name)¶

Return value: New reference. Part of the Stable ABI.

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 PyObject_GetOptionalAttr() instead.

PyObject *PyObject_GetAttrString(PyObject *o, const char *attr_name)¶

Return value: New reference. Part of the Stable ABI.

This is the same as PyObject_GetAttr(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

If the missing attribute should not be treated as a failure, you can use PyObject_GetOptionalAttrString() instead.

int PyObject_GetOptionalAttr(PyObject *obj, PyObject *attr_name, PyObject **result);¶

Part of the Stable ABI since version 3.13.

Variant of PyObject_GetAttr() which doesn’t raise AttributeError if the attribute is not found.

If the attribute is found, return 1 and set *result to a new strong reference to the attribute. If the attribute is not found, return 0 and set *result to NULL; the AttributeError is silenced. If an error other than AttributeError is raised, return -1 and set *result to NULL.

Added in version 3.13.

int PyObject_GetOptionalAttrString(PyObject *obj, const char *attr_name, PyObject **result);¶: Part of the Stable ABI since version 3.13.
This is the same as PyObject_GetOptionalAttr(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

Added in version 3.13.

PyObject *PyObject_GenericGetAttr(PyObject *o, PyObject *name)¶: Return value: New reference. Part of the Stable ABI.
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 __dict__ (if present). As outlined in Implementing Descriptors, data descriptors take preference over instance attributes, while non-data descriptors don’t. Otherwise, an AttributeError is raised.

int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v)¶

Part of the Stable ABI.

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 PyObject_DelAttr(), but there are currently no plans to remove it.

int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)¶

Part of the Stable ABI.

This is the same as PyObject_SetAttr(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

If v is NULL, the attribute is deleted, but this feature is deprecated in favour of using PyObject_DelAttrString().

The number of different attribute names passed to this function should be kept small, usually by using a statically allocated string as attr_name. For attribute names that aren’t known at compile time, prefer calling PyUnicode_FromString() and PyObject_SetAttr() directly. For more details, see PyUnicode_InternFromString(), which may be used internally to create a key object.

int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)¶: Part of the Stable ABI.
Generic attribute setter and deleter 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 or deleting the attribute in the instance dictionary. Otherwise, the attribute is set or deleted in the object’s __dict__ (if present). On success, 0 is returned, otherwise an AttributeError is raised and -1 is returned.

int PyObject_DelAttr(PyObject *o, PyObject *attr_name)¶: Part of the Stable ABI since version 3.13.
Delete attribute named attr_name, for object o. Returns -1 on failure. This is the equivalent of the Python statement del o.attr_name.

int PyObject_DelAttrString(PyObject *o, const char *attr_name)¶

Part of the Stable ABI since version 3.13.

This is the same as PyObject_DelAttr(), but attr_name is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

The number of different attribute names passed to this function should be kept small, usually by using a statically allocated string as attr_name. For attribute names that aren’t known at compile time, prefer calling PyUnicode_FromString() and PyObject_DelAttr() directly. For more details, see PyUnicode_InternFromString(), which may be used internally to create a key object for lookup.

PyObject *PyObject_GenericGetDict(PyObject *o, void *context)¶

Return value: New reference. Part of the Stable ABI since version 3.10.

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 __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 PyObject_GetAttr() when accessing an attribute on the object.

On failure, returns NULL with an exception set.

Added in version 3.3.

int PyObject_GenericSetDict(PyObject *o, PyObject *value, void *context)¶: Part of the Stable ABI since version 3.7.
A generic implementation for the setter of a __dict__ descriptor. This implementation does not allow the dictionary to be deleted.

Added in version 3.3.

PyObject **_PyObject_GetDictPtr(PyObject *obj)¶

Return a pointer to __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 PyObject_GetAttr() when accessing an attribute on the object.

PyObject *PyObject_RichCompare(PyObject *o1, PyObject *o2, int opid)¶: Return value: New reference. Part of the Stable ABI.
Compare the values of o1 and o2 using the operation specified by opid, which must be one of Py_LT, Py_LE, Py_EQ, Py_NE, Py_GT, or 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.

int PyObject_RichCompareBool(PyObject *o1, PyObject *o2, int opid)¶: Part of the Stable ABI.
Compare the values of o1 and o2 using the operation specified by opid, like PyObject_RichCompare(), but returns -1 on error, 0 if the result is false, 1 otherwise.

Note

If o1 and o2 are the same object, PyObject_RichCompareBool() will always return 1 for Py_EQ and 0 for Py_NE.

PyObject *PyObject_Format(PyObject *obj, PyObject *format_spec)¶

Part of the Stable ABI.

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.

PyObject *PyObject_Repr(PyObject *o)¶

Return value: New reference. Part of the Stable ABI.

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 repr() built-in function.

If argument is NULL, return the string '<NULL>'.

Changed in version 3.4: This function now includes a debug assertion to help ensure that it does not silently discard an active exception.

PyObject *PyObject_ASCII(PyObject *o)¶: Return value: New reference. Part of the Stable ABI.
As