
Object Protocol
***************

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)

   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.

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.

PyObject* PyObject_GetAttr(PyObject *o, PyObject *attr_name)
    Return value: New reference.

   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.

   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``.

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``.

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``.

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_RichCompare(PyObject *o1, PyObject *o2, int opid)
    Return value: New reference.

   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)

   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*.

int PyObject_Cmp(PyObject *o1, PyObject *o2, int *result)

   Compare the values of *o1* and *o2* using a routine provided by
   *o1*, if one exists, otherwise with a routine provided by *o2*.
   The result of the comparison is returned in *result*.  Returns
   ``-1`` on failure.  This is the equivalent of the Python statement
   ``result = cmp(o1, o2)``.

int PyObject_Compare(PyObject *o1, PyObject *o2)

   Compare the values of *o1* and *o2* using a routine provided by
   *o1*, if one exists, otherwise with a routine provided by *o2*.
   Returns the result of the comparison on success.  On error, the
   value returned is undefined; use ``PyErr_Occurred`` to detect an
   error.  This is equivalent to the Python expression ``cmp(o1,
   o2)``.

PyObject* PyObject_Repr(PyObject *o)
    Return value: New reference.

   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.

PyObject* PyObject_ASCII(PyObject *o)

   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.

   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.

PyObject* PyObject_Bytes(PyObject *o)

   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)``.

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, ``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 ``__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 ``A`` and ``B`` are class objects, ``B``
is a subclass of ``A`` if it inherits from ``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*,
``PyObject_IsSubclass`` returns true.  If *A* and *B* are different
objects, *B*'s ``__bases__`` attribute is searched in a depth-first
fashion for *A* --- the presence of the ``__bases__`` attribute is
considered sufficient for this determination.

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.

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.

PyObject* PyObject_Call(PyObject *callable_object, PyObject *args, PyObject *kw)
    Return value: New reference.

   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)``.

PyObject* PyObject_CallObject(PyObject *callable_object, PyObject *args)
    Return value: New reference.

   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)``.

PyObject* PyObject_CallFunction(PyObject *callable, char *format, ...)
    Return value: New reference.

   Call a callable Python object *callable*, with a variable number of
   C arguments. The C arguments are described using a
   ``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 ``PyObject *`` args, ``PyObject_CallFunctionObjArgs`` is a
   faster alternative.

PyObject* PyObject_CallMethod(PyObject *o, char *method, char *format, ...)
    Return value: New reference.

   Call the method named *method* of object *o* with a variable number
   of C arguments.  The C arguments are described by a
   ``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 ``PyObject *`` args,
   ``PyObject_CallMethodObjArgs`` is a faster alternative.

PyObject* PyObject_CallFunctionObjArgs(PyObject *callable, ..., NULL)
    Return value: New reference.

   Call a callable Python object *callable*, with a variable number of
   ``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.

PyObject* PyObject_CallMethodObjArgs(PyObject *o, PyObject *name, ..., NULL)
    Return value: New reference.

   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 ``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.

long PyObject_Hash(PyObject *o)

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

long PyObject_HashNotImplemented(PyObject *o)

   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.

   New in version 2.6.

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``.

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``.

PyObject* PyObject_Type(PyObject *o)
    Return value: New reference.

   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 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 ``PyTypeObject*``, except when the incremented reference count
   is needed.

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*.

Py_ssize_t PyObject_Length(PyObject *o)
Py_ssize_t PyObject_Size(PyObject *o)

   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)``.

PyObject* PyObject_GetItem(PyObject *o, PyObject *key)
    Return value: New reference.

   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)

   Map the object *key* to the value *v*.  Returns ``-1`` on failure.
   This is the equivalent of the Python statement ``o[key] = v``.

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]``.

PyObject* PyObject_Dir(PyObject *o)
    Return value: New reference.

   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.

   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.
