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).

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)
    * Part of the Stable ABI.*

   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 that exceptions which occur while calling "__getattr__()" and
   "__getattribute__()" methods will get suppressed. To get error
   reporting use "PyObject_GetAttr()" instead.

int PyObject_HasAttrString(PyObject *o, const char *attr_name)
    * Part of the Stable ABI.*

   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 that exceptions which occur while calling "__getattr__()" and
   "__getattribute__()" methods and creating a temporary string object
   will get suppressed. To get error reporting use
   "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".

PyObject *PyObject_GetAttrString(PyObject *o, const char *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".

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.*

   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, but this feature is
   deprecated in favour of using "PyObject_DelAttrString()".

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)

   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)

   Delete attribute named *attr_name*, for object *o*. Returns "-1" on
   failure. This is the equivalent of the Python statement "del
   o.attr_name".

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.

   Nuovo nella versione 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.

   Nuovo nella versione 3.3.

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*, which must be one of "Py_LT", "Py_LE", "Py_EQ", "Py_NE",
   "Py_GT", or "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*.

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)
    * 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.

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

   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)
    *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 "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)
    *Return value: New reference.** Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

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

   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)
    * Part of the Stable ABI.*

   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)".

   Nuovo nella versione 3.4.

PyObject *PyObject_GetItem(PyObject *o, PyObject *key)
    *Return value: New reference.** Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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)
    * Part of the Stable ABI.*

   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]".

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

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

   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_GetAIter(PyObject *o)
    *Return value: New reference.** Part of the Stable ABI since
   version 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.

   Nuovo nella versione 3.10.
