6.1. 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)¶: 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)¶: 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)¶: 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)¶: 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_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 __dict__ (if present). 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_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 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.

Note

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

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

int PyObject_Compare(PyObject *o1, PyObject *o2)¶

PyObject* PyObject_Repr(PyObject *o)¶

PyObject* PyObject_Str(PyObject *o)¶

PyObject* PyObject_Bytes(PyObject *o)¶

PyObject* PyObject_Unicode(PyObject *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.

New in version 2.1.

Changed in version 2.2: Support for a tuple as the second argument added.

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.

New in version 2.1.

Changed in version 2.3: Older versions of Python did not support a tuple as the second argument.

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)¶

PyObject* PyObject_CallObject(PyObject *callable_object, PyObject *args)¶

PyObject* PyObject_CallFunction(PyObject *callable, char *format, ...)¶

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 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)¶: 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.

New in version 2.2.

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 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.

New in version 2.2.

long PyObject_Hash(PyObject *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)¶

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.

New in version 2.2.

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

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].

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].

int PyObject_AsFileDescriptor(PyObject *o)¶: Derives a file descriptor from a Python object. If the object is an integer or long integer, its value is returned. If not, the object’s fileno() method is called if it exists; the method must return an integer or long integer, which is returned as the file descriptor value. Returns -1 on failure.

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 PyErr_Occurred() will return false.

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 TypeError and returns NULL if the object cannot be iterated.