Object Protocol

PyObject*Py_GetConstant(unsignedintconstant_id)

Part of theStable ABIsince version 3.13.

Get astrong referenceto a constant.

Set an exception and returnNULLifconstant_idis invalid.

constant_idmust be one of these constant identifiers:

Constant Identifier	Value	Returned object
Py_CONSTANT_NONE	0	None
Py_CONSTANT_FALSE	1	False
Py_CONSTANT_TRUE	2	True
Py_CONSTANT_ELLIPSIS	3	Ellipsis
Py_CONSTANT_NOT_IMPLEMENTED	4	NotImplemented
Py_CONSTANT_ZERO	5	0
Py_CONSTANT_ONE	6	1
Py_CONSTANT_EMPTY_STR	7	''
Py_CONSTANT_EMPTY_BYTES	8	b''
Py_CONSTANT_EMPTY_TUPLE	9	()

Numeric values are only given for projects which cannot use the constant identifiers.

Added in version 3.13.

CPython implementation detail:In CPython, all of these constants areimmortal.

PyObject*Py_GetConstantBorrowed(unsignedintconstant_id)

Part of theStable ABIsince version 3.13.

Similar toPy_GetConstant(),but return aborrowed reference.

This function is primarily intended for backwards compatibility: usingPy_GetConstant()is recommended for new code.

The reference is borrowed from the interpreter, and is valid until the interpreter finalization.

Added in version 3.13.

PyObject*Py_NotImplemented

TheNotImplementedsingleton, used to signal that an operation is not implemented for the given type combination.

Py_RETURN_NOTIMPLEMENTED

Properly handle returningPy_NotImplementedfrom within a C function (that is, create a newstrong reference toNotImplementedand return it).

Py_PRINT_RAW

Flag to be used with multiple functions that print the object (like PyObject_Print()andPyFile_WriteObject()). If passed, these function would use thestr()of the object instead of therepr().

intPyObject_Print(PyObject*o,FILE*fp,intflags)

Print an objecto,on filefp.Returns-1on error. The flags argument is used to enable certain printing options. The only option currently supported isPy_PRINT_RAW;if given, thestr()of the object is written instead of therepr().

intPyObject_HasAttrWithError(PyObject*o,constchar*attr_name)

Part of theStable ABIsince version 3.13.

Returns1ifohas the attributeattr_name,and0otherwise. This is equivalent to the Python expressionhasattr(o,attr_name). On failure, return-1.

Added in version 3.13.

intPyObject_HasAttrStringWithError(PyObject*o,constchar*attr_name)

Part of theStable ABIsince version 3.13.

This is the same asPyObject_HasAttrWithError(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

Added in version 3.13.

intPyObject_HasAttr(PyObject*o,PyObject*attr_name)

Part of theStable ABI.

Returns1ifohas the attributeattr_name,and0otherwise. This function always succeeds.

Note

Exceptions that occur when this calls__getattr__()and __getattribute__()methods are silently ignored. For proper error handling, usePyObject_HasAttrWithError(), PyObject_GetOptionalAttr()orPyObject_GetAttr()instead.

intPyObject_HasAttrString(PyObject*o,constchar*attr_name)

Part of theStable ABI.

This is the same asPyObject_HasAttr(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

Note

Exceptions that occur when this calls__getattr__()and __getattribute__()methods or while creating the temporary strobject are silently ignored. For proper error handling, usePyObject_HasAttrStringWithError(), PyObject_GetOptionalAttrString() orPyObject_GetAttrString()instead.

PyObject*PyObject_GetAttr(PyObject*o,PyObject*attr_name)

Return value: New reference.Part of theStable ABI.

Retrieve an attribute namedattr_namefrom objecto.Returns the attribute value on success, orNULLon failure. This is the equivalent of the Python expressiono.attr_name.

If the missing attribute should not be treated as a failure, you can use PyObject_GetOptionalAttr()instead.

PyObject*PyObject_GetAttrString(PyObject*o,constchar*attr_name)

Return value: New reference.Part of theStable ABI.

This is the same asPyObject_GetAttr(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

If the missing attribute should not be treated as a failure, you can use PyObject_GetOptionalAttrString()instead.

intPyObject_GetOptionalAttr(PyObject*obj,PyObject*attr_name,PyObject**result);

Part of theStable ABIsince version 3.13.

Variant ofPyObject_GetAttr()which doesn’t raise AttributeErrorif the attribute is not found.

If the attribute is found, return1and set*resultto a new strong referenceto the attribute. If the attribute is not found, return0and set*resulttoNULL; theAttributeErroris silenced. If an error other thanAttributeErroris raised, return-1and set*resulttoNULL.

Added in version 3.13.

intPyObject_GetOptionalAttrString(PyObject*obj,constchar*attr_name,PyObject**result);

Part of theStable ABIsince version 3.13.

This is the same asPyObject_GetOptionalAttr(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

Added in version 3.13.

PyObject*PyObject_GenericGetAttr(PyObject*o,PyObject*name)

Return value: New reference.Part of theStable ABI.

Generic attribute getter function that is meant to be put into a type object’stp_getattroslot. 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 inImplementing Descriptors, data descriptors take preference over instance attributes, while non-data descriptors don’t. Otherwise, anAttributeErroris raised.

intPyObject_SetAttr(PyObject*o,PyObject*attr_name,PyObject*v)

Part of theStable ABI.

Set the value of the attribute namedattr_name,for objecto,to the value v.Raise an exception and return-1on failure; return0on success. This is the equivalent of the Python statement o.attr_name=v.

IfvisNULL,the attribute is deleted. This behaviour is deprecated in favour of usingPyObject_DelAttr(),but there are currently no plans to remove it.

intPyObject_SetAttrString(PyObject*o,constchar*attr_name,PyObject*v)

Part of theStable ABI.

This is the same asPyObject_SetAttr(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

IfvisNULL,the attribute is deleted, but this feature is deprecated in favour of usingPyObject_DelAttrString().

The number of different attribute names passed to this function should be kept small, usually by using a statically allocated string asattr_name. For attribute names that aren’t known at compile time, prefer calling PyUnicode_FromString()andPyObject_SetAttr()directly. For more details, seePyUnicode_InternFromString(),which may be used internally to create a key object.

intPyObject_GenericSetAttr(PyObject*o,PyObject*name,PyObject*value)

Part of theStable ABI.

Generic attribute setter and deleter function that is meant to be put into a type object’stp_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,0is returned, otherwise anAttributeError is raised and-1is returned.

intPyObject_DelAttr(PyObject*o,PyObject*attr_name)

Part of theStable ABIsince version 3.13.

Delete attribute namedattr_name,for objecto.Returns-1on failure. This is the equivalent of the Python statementdelo.attr_name.

intPyObject_DelAttrString(PyObject*o,constchar*attr_name)

Part of theStable ABIsince version 3.13.

This is the same asPyObject_DelAttr(),butattr_nameis specified as aconstchar*UTF-8 encoded bytes string, rather than aPyObject*.

The number of different attribute names passed to this function should be kept small, usually by using a statically allocated string asattr_name. For attribute names that aren’t known at compile time, prefer calling PyUnicode_FromString()andPyObject_DelAttr()directly. For more details, seePyUnicode_InternFromString(),which may be used internally to create a key object for lookup.

PyObject*PyObject_GenericGetDict(PyObject*o,void*context)

Return value: New reference.Part of theStable ABIsince version 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 objecto.PassNULLforcontextwhen calling it. Since this function may need to allocate memory for the dictionary, it may be more efficient to callPyObject_GetAttr() when accessing an attribute on the object.

On failure, returnsNULLwith an exception set.

Added in version 3.3.

intPyObject_GenericSetDict(PyObject*o,PyObject*value,void*context)

Part of theStable ABIsince version 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 objectobj. If there is no__dict__,returnNULLwithout setting an exception.

This function may need to allocate memory for the dictionary, so it may be more efficient to callPyObject_GetAttr() when accessing an attribute on the object.

PyObject*PyObject_RichCompare(PyObject*o1,PyObject*o2,intopid)

Return value: New reference.Part of theStable ABI.

Compare the values ofo1ando2using the operation specified byopid, which must be one ofPy_LT,Py_LE,Py_EQ, Py_NE,Py_GT,orPy_GE,corresponding to<, <=,==,!=,>,or>=respectively. This is the equivalent of the Python expressiono1opo2,whereopis the operator corresponding toopid.Returns the value of the comparison on success, orNULLon failure.

intPyObject_RichCompareBool(PyObject*o1,PyObject*o2,intopid)

Part of theStable ABI.

Compare the values ofo1ando2using the operation specified byopid, likePyObject_RichCompare(),but returns-1on error,0if the result is false,1otherwise.

Note

Ifo1ando2are the same object,PyObject_RichCompareBool() will always return1forPy_EQand0forPy_NE.

PyObject*PyObject_Format(PyObject*obj,PyObject*format_spec)

Part of theStable ABI.

Formatobjusingformat_spec.This is equivalent to the Python expressionformat(obj,format_spec).

format_specmay beNULL.In this case the call is equivalent toformat(obj). Returns the formatted string on success,NULLon failure.

PyObject*PyObject_Repr(PyObject*o)

Return value: New reference.Part of theStable ABI.

Compute a string representation of objecto.Returns the string representation on success,NULLon failure. This is the equivalent of the Python expressionrepr(o).Called by therepr()built-in function.

Changed in version 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 theStable ABI.

AsPyObject_Repr(),compute a string representation of objecto,but escape the non-ASCII characters in the string returned by PyObject_Repr()with\x,\uor\Uescapes. This generates a string similar to that returned byPyObject_Repr()in Python 2. Called by theascii()built-in function.

PyObject*PyObject_Str(PyObject*o)

Return value: New reference.Part of theStable ABI.

Compute a string representation of objecto.Returns the string representation on success,NULLon failure. This is the equivalent of the Python expressionstr(o).Called by thestr()built-in function and, therefore, by theprint()function.

Changed in version 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 theStable ABI.

Compute a bytes representation of objecto.NULLis returned on failure and a bytes object on success. This is equivalent to the Python expressionbytes(o),whenois not an integer. Unlikebytes(o), a TypeError is raised whenois an integer instead of a zero-initialized bytes object.

intPyObject_IsSubclass(PyObject*derived,PyObject*cls)

Part of theStable ABI.

Return1if the classderivedis identical to or derived from the class cls,otherwise return0.In case of an error, return-1.

Ifclsis a tuple, the check will be done against every entry incls. The result will be1when at least one of the checks returns1, otherwise it will be0.

Ifclshas a__subclasscheck__()method, it will be called to determine the subclass status as described inPEP 3119.Otherwise, derivedis a subclass ofclsif it is a direct or indirect subclass, i.e. contained incls.__mro__.

Normally only class objects, i.e. instances oftypeor a derived class, are considered classes. However, objects can override this by having a__bases__attribute (which must be a tuple of base classes).

intPyObject_IsInstance(PyObject*inst,PyObject*cls)

Part of theStable ABI.

Return1ifinstis an instance of the classclsor a subclass of cls,or0if not. On error, returns-1and sets an exception.

Ifclsis a tuple, the check will be done against every entry incls. The result will be1when at least one of the checks returns1, otherwise it will be0.

Ifclshas a__instancecheck__()method, it will be called to determine the subclass status as described inPEP 3119.Otherwise,inst is an instance ofclsif its class is a subclass ofcls.

An instanceinstcan override what is considered its class by having a __class__attribute.

An objectclscan 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_tPyObject_Hash(PyObject*o)

Part of theStable ABI.

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

Changed in version 3.2:The return type is now Py_hash_t. This is a signed integer the same size asPy_ssize_t.

Py_hash_tPyObject_HashNotImplemented(PyObject*o)

Part of theStable ABI.

Set aTypeErrorindicating thattype(o)is nothashableand return-1. This function receives special treatment when stored in atp_hashslot, allowing a type to explicitly indicate to the interpreter that it is not hashable.

intPyObject_IsTrue(PyObject*o)

Part of theStable ABI.

Returns1if the objectois considered to be true, and0otherwise. This is equivalent to the Python expressionnotnoto.On failure, return -1.

intPyObject_Not(PyObject*o)

Part of theStable ABI.

Returns0if the objectois considered to be true, and1otherwise. This is equivalent to the Python expressionnoto.On failure, return -1.

PyObject*PyObject_Type(PyObject*o)

Return value: New reference.Part of theStable ABI.

Whenois non-NULL,returns a type object corresponding to the object type of objecto.On failure, raisesSystemErrorand returnsNULL.This is equivalent to the Python expressiontype(o). This function creates a newstrong referenceto the return value. There’s really no reason to use this function instead of thePy_TYPE()function, which returns a pointer of typePyTypeObject*,except when a new strong referenceis needed.

intPyObject_TypeCheck(PyObject*o,PyTypeObject*type)

Return non-zero if the objectois of typetypeor a subtype oftype,and 0otherwise. Both parameters must be non-NULL.

Py_ssize_tPyObject_Size(PyObject*o)

Py_ssize_tPyObject_Length(PyObject*o)

Part of theStable ABI.

Return the length of objecto.If the objectoprovides either the sequence and mapping protocols, the sequence length is returned. On error,-1is returned. This is the equivalent to the Python expressionlen(o).

Py_ssize_tPyObject_LengthHint(PyObject*o,Py_ssize_tdefaultvalue)

Return an estimated length for the objecto.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 expressionoperator.length_hint(o,defaultvalue).

Added in version 3.4.

PyObject*PyObject_GetItem(PyObject*o,PyObject*key)

Return value: New reference.Part of theStable ABI.

Return element ofocorresponding to the objectkeyorNULLon failure. This is the equivalent of the Python expressiono[key].

intPyObject_SetItem(PyObject*o,PyObject*key,PyObject*v)

Part of theStable ABI.

Map the objectkeyto the valuev.Raise an exception and return-1on failure; return0on success. This is the equivalent of the Python statemento[key]=v.This functiondoes notsteal a reference tov.

intPyObject_DelItem(PyObject*o,PyObject*key)

Part of theStable ABI.

Remove the mapping for the objectkeyfrom the objecto.Return-1 on failure. This is equivalent to the Python statementdelo[key].

PyObject*PyObject_Dir(PyObject*o)

Return value: New reference.Part of theStable ABI.

This is equivalent to the Python expressiondir(o),returning a (possibly empty) list of strings appropriate for the object argument, orNULLif there was an error. If the argument isNULL,this is like the Pythondir(), returning the names of the current locals; in this case, if no execution frame is active thenNULLis returned butPyErr_Occurred()will return false.

PyObject*PyObject_GetIter(PyObject*o)

Return value: New reference.Part of theStable ABI.

This is equivalent to the Python expressioniter(o).It returns a new iterator for the object argument, or the object itself if the object is already an iterator. RaisesTypeErrorand returnsNULLif the object cannot be iterated.

PyObject*PyObject_GetAIter(PyObject*o)

Return value: New reference.Part of theStable ABIsince version 3.10.

This is the equivalent to the Python expressionaiter(o).Takes an AsyncIterableobject and returns anAsyncIteratorfor it. This is typically a new iterator but if the argument is an AsyncIterator,this returns itself. RaisesTypeErrorand returnsNULLif the object cannot be iterated.

Added in version 3.10.

void*PyObject_GetTypeData(PyObject*o,PyTypeObject*cls)

Part of theStable ABIsince version 3.12.

Get a pointer to subclass-specific data reserved forcls.

The objectomust be an instance ofcls,andclsmust have been created using negativePyType_Spec.basicsize. Python does not check this.

On error, set an exception and returnNULL.

Added in version 3.12.

Py_ssize_tPyType_GetTypeDataSize(PyTypeObject*cls)

Part of theStable ABIsince version 3.12.

Return the size of the instance memory space reserved forcls,i.e. the size of the memoryPyObject_GetTypeData()returns.

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

The typeclsmusthave been created using negativePyType_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 returnNULL. TypeErroris raised ifodoes not have Py_TPFLAGS_ITEMS_AT_ENDset.

Added in version 3.12.

intPyObject_VisitManagedDict(PyObject*obj,visitprocvisit,void*arg)

Visit the managed dictionary ofobj.

This function must only be called in a traverse function of the type which has thePy_TPFLAGS_MANAGED_DICTflag set.

Added in version 3.13.

voidPyObject_ClearManagedDict(PyObject*obj)

Clear the managed dictionary ofobj.

This function must only be called in a traverse function of the type which has thePy_TPFLAGS_MANAGED_DICTflag set.

Added in version 3.13.