| .. highlightlang:: c |
| |
| .. _object: |
| |
| Object Protocol |
| =============== |
| |
| |
| .. cfunction:: 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 :const:`Py_PRINT_RAW`; if given, the :func:`str` of the object is written |
| instead of the :func:`repr`. |
| |
| |
| .. cfunction:: 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. |
| |
| |
| .. cfunction:: 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. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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 :const:`Py_LT`, :const:`Py_LE`, :const:`Py_EQ`, |
| :const:`Py_NE`, :const:`Py_GT`, or :const:`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. |
| |
| |
| .. cfunction:: 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 :const:`Py_LT`, :const:`Py_LE`, :const:`Py_EQ`, |
| :const:`Py_NE`, :const:`Py_GT`, or :const:`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*. |
| |
| |
| .. cfunction:: int PyObject_Cmp(PyObject *o1, PyObject *o2, int *result) |
| |
| .. index:: builtin: cmp |
| |
| 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)``. |
| |
| |
| .. cfunction:: int PyObject_Compare(PyObject *o1, PyObject *o2) |
| |
| .. index:: builtin: cmp |
| |
| 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 |
| :cfunc:`PyErr_Occurred` to detect an error. This is equivalent to the Python |
| expression ``cmp(o1, o2)``. |
| |
| |
| .. cfunction:: PyObject* PyObject_Repr(PyObject *o) |
| |
| .. index:: builtin: repr |
| |
| 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 :func:`repr` built-in function and |
| by reverse quotes. |
| |
| |
| .. cfunction:: PyObject* PyObject_Str(PyObject *o) |
| |
| .. index:: builtin: str |
| |
| 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 :func:`str` built-in function and |
| by the :keyword:`print` statement. |
| |
| |
| .. cfunction:: PyObject* PyObject_Bytes(PyObject *o) |
| |
| .. index:: builtin: bytes |
| |
| Compute a bytes representation of object *o*. In 2.x, this is just a alias |
| for :cfunc:`PyObject_Str`. |
| |
| |
| .. cfunction:: PyObject* PyObject_Unicode(PyObject *o) |
| |
| .. index:: builtin: unicode |
| |
| Compute a Unicode string representation of object *o*. Returns the Unicode |
| string representation on success, *NULL* on failure. This is the equivalent of |
| the Python expression ``unicode(o)``. Called by the :func:`unicode` built-in |
| function. |
| |
| |
| .. cfunction:: 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, :cfunc:`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 :attr:`__class__` attribute --- the class relationship |
| of the value of that attribute with *cls* will be used to determine the result |
| of this function. |
| |
| .. versionadded:: 2.1 |
| |
| .. versionchanged:: 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 :class:`A` and :class:`B` are class objects, :class:`B` is a subclass of |
| :class:`A` if it inherits from :class:`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*, :cfunc:`PyObject_IsSubclass` returns true. If *A* and *B* |
| are different objects, *B*'s :attr:`__bases__` attribute is searched in a |
| depth-first fashion for *A* --- the presence of the :attr:`__bases__` attribute |
| is considered sufficient for this determination. |
| |
| |
| .. cfunction:: 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. |
| |
| .. versionadded:: 2.1 |
| |
| .. versionchanged:: 2.3 |
| Older versions of Python did not support a tuple as the second argument. |
| |
| |
| .. cfunction:: 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. |
| |
| |
| .. cfunction:: PyObject* PyObject_Call(PyObject *callable_object, PyObject *args, PyObject *kw) |
| |
| .. index:: builtin: apply |
| |
| 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 |
| ``apply(callable_object, args, kw)`` or ``callable_object(*args, **kw)``. |
| |
| .. versionadded:: 2.2 |
| |
| |
| .. cfunction:: PyObject* PyObject_CallObject(PyObject *callable_object, PyObject *args) |
| |
| .. index:: builtin: apply |
| |
| 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 ``apply(callable_object, args)`` or |
| ``callable_object(*args)``. |
| |
| |
| .. cfunction:: PyObject* PyObject_CallFunction(PyObject *callable, char *format, ...) |
| |
| .. index:: builtin: apply |
| |
| Call a callable Python object *callable*, with a variable number of C arguments. |
| The C arguments are described using a :cfunc:`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 ``apply(callable, args)`` or |
| ``callable(*args)``. Note that if you only pass :ctype:`PyObject \*` args, |
| :cfunc:`PyObject_CallFunctionObjArgs` is a faster alternative. |
| |
| |
| .. cfunction:: 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 :cfunc:`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 :ctype:`PyObject \*` args, |
| :cfunc:`PyObject_CallMethodObjArgs` is a faster alternative. |
| |
| |
| .. cfunction:: PyObject* PyObject_CallFunctionObjArgs(PyObject *callable, ..., NULL) |
| |
| Call a callable Python object *callable*, with a variable number of |
| :ctype:`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. |
| |
| .. versionadded:: 2.2 |
| |
| |
| .. cfunction:: 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 |
| :ctype:`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. |
| |
| .. versionadded:: 2.2 |
| |
| |
| .. cfunction:: long PyObject_Hash(PyObject *o) |
| |
| .. index:: builtin: hash |
| |
| Compute and return the hash value of an object *o*. On failure, return ``-1``. |
| This is the equivalent of the Python expression ``hash(o)``. |
| |
| |
| .. cfunction:: long PyObject_HashNotImplemented(PyObject *o) |
| |
| Set a :exc:`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. |
| |
| .. versionadded:: 2.6 |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: PyObject* PyObject_Type(PyObject *o) |
| |
| .. index:: builtin: type |
| |
| When *o* is non-*NULL*, returns a type object corresponding to the object type |
| of object *o*. On failure, raises :exc:`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 :ctype:`PyTypeObject\*`, except when the incremented reference |
| count is needed. |
| |
| |
| .. cfunction:: 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*. |
| |
| .. versionadded:: 2.2 |
| |
| |
| .. cfunction:: Py_ssize_t PyObject_Length(PyObject *o) |
| Py_ssize_t PyObject_Size(PyObject *o) |
| |
| .. index:: builtin: len |
| |
| 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)``. |
| |
| |
| .. cfunction:: 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]``. |
| |
| |
| .. cfunction:: 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``. |
| |
| |
| .. cfunction:: 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]``. |
| |
| |
| .. cfunction:: 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 :meth:`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. |
| |
| |
| .. cfunction:: 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 :cfunc:`PyErr_Occurred` will return false. |
| |
| |
| .. cfunction:: 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 :exc:`TypeError` and returns *NULL* if the object cannot be |
| iterated. |