# Object Protocol

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 function would 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_HasAttr(PyObject *o, PyObject *attr_name)
  Parte del ABI Stabile.

  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.

  Nota

  Exceptions that occur when this calls `__getattr__()` and `__getattribute__()` methods are silently ignored. For proper error handling, use `PyObject_GetAttr()` instead.

int PyObject_HasAttrString(PyObject *o, const char *attr_name)
  Parte del ABI Stabile.

  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*.

  Nota

  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_GetAttrString()` instead.

PyObject *PyObject_GetAttr(PyObject *o, PyObject *attr_name)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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`.

PyObject *PyObject_GetAttrString(PyObject *o, const char *attr_name)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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*.

PyObject *PyObject_GenericGetAttr(PyObject *o, PyObject *name)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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)
  Parte del ABI Stabile.

  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)
  Parte del ABI Stabile.

  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)
  Parte del ABI Stabile.

  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)

  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)

  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)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile dalla versione 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)
  Parte del ABI Stabile dalla versione 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)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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)
  Parte del ABI Stabile.

  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.

Nota

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)
  Parte del ABI Stabile.

  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)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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.

  Cambiato nella versione 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)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  As `PyObject_Repr()`, compute a string representation of object o, but escape the non-ASCII characters in the string returned by `PyObject_Repr()` with `\x`, `\u` or `\U` escapes. This generates a string similar to that returned by `PyObject_Repr()` in Python 2. Called by the `ascii()` built-in function.

PyObject *PyObject_Str(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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 `str()` built-in function and, therefore, by the `print()` function.

  Cambiato nella versione 3.4: This function now includes a debug assertion to help ensure that it does not silently discard an active exception.

PyObject *PyObject_Bytes(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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.

int PyObject_IsSubclass(PyObject *derived, PyObject *cls)
  Parte del ABI Stabile.

  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 `__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 `type` or a derived class, are considered classes. However, objects can override this by having a `__bases__` attribute (which must be a tuple of base classes).

int PyObject_IsInstance(PyObject *inst, PyObject *cls)
  Parte del ABI Stabile.

  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 `__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 `__class__` attribute.

  An object cls can override if it is considered a class, and what its base classes are, by having a `__bases__` attribute (which must be a tuple of base classes).

Py_hash_t PyObject_Hash(PyObject *o)
  Parte del ABI Stabile.

  Compute and return the hash value of an object o. On failure, return `-1`. This is the equivalent of the Python expression `hash(o)`.

  Cambiato nella versione 3.2: The return type is now Py_hash_t. This is a signed integer the same size as `Py_ssize_t`.

Py_hash_t PyObject_HashNotImplemented(PyObject *o)
  Parte del ABI Stabile.

  Set a `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.

int PyObject_IsTrue(PyObject *o)
  Parte del ABI Stabile.

  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`.

int PyObject_Not(PyObject *o)
  Parte del ABI Stabile.

  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`.

PyObject *PyObject_Type(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  When o is non-`NULL`, returns a type object corresponding to the object type of object o. On failure, raises `SystemError` and returns `NULL`. This is equivalent to the Python expression `type(o)`. This function creates a new strong reference to the return value. There’s really no reason to use this function instead of the `Py_TYPE()` function, which returns a pointer of type PyTypeObject*, except when a new strong reference is needed.

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`.

Py_ssize_t PyObject_Size(PyObject *o)
Py_ssize_t PyObject_Length(PyObject *o)
  Parte del ABI Stabile.

  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)`.

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 `__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)`.

  Added in version 3.4.

PyObject *PyObject_GetItem(PyObject *o, PyObject *key)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  Return element of o corresponding to the object key or `NULL` on failure. This is the equivalent of the Python expression `o[key]`.

int PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v)
  Parte del ABI Stabile.

  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.

int PyObject_DelItem(PyObject *o, PyObject *key)
  Parte del ABI Stabile.

  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]`.

int PyObject_DelItemString(PyObject *o, const char *key)
  Parte del ABI Stabile.

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

PyObject *PyObject_Dir(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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 `PyErr_Occurred()` will return false.

PyObject *PyObject_GetIter(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  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 `TypeError` and returns `NULL` if the object cannot be iterated.

PyObject *PyObject_SelfIter(PyObject *obj)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile.

  This is equivalent to the Python `__iter__(self): return self` method. It is intended for iterator types, to be used in the `PyTypeObject.tp_iter` slot.

PyObject *PyObject_GetAIter(PyObject *o)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile dalla versione 3.10.

  This is the equivalent to the Python expression `aiter(o)`. Takes an `AsyncIterable` object and returns an `AsyncIterator` for it. This is typically a new iterator but if the argument is an `AsyncIterator`, this returns itself. Raises `TypeError` and returns `NULL` if the object cannot be iterated.

  Added in version 3.10.

void *PyObject_GetTypeData(PyObject *o, PyTypeObject *cls)
  Parte del ABI Stabile dalla versione 3.12.

  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 `PyType_Spec.basicsize`. Python does not check this.

  On error, set an exception and return `NULL`.

  Added in version 3.12.

Py_ssize_t PyType_GetTypeDataSize(PyTypeObject *cls)
  Parte del ABI Stabile dalla versione 3.12.

  Return the size of the instance memory space reserved for cls, i.e. the size of the memory `PyObject_GetTypeData()` returns.

  This may be larger than requested using `-PyType_Spec.basicsize`; it is safe to use this larger size (e.g. with `memset()`).

  The type cls must have been created using negative `PyType_Spec.basicsize`. Python does not check this.

  On error, set an exception and return a negative value.

  Added in version 3.12.

void *PyObject_GetItemData(PyObject *o)

  Get a pointer to per-item data for a class with `Py_TPFLAGS_ITEMS_AT_END`.

  On error, set an exception and return `NULL`. `TypeError` is raised if o does not have `Py_TPFLAGS_ITEMS_AT_END` set.

  Added in version 3.12.