Object Protocol¶

PyObject*Py_NotImplemented¶

TheNotImplemented singleton, used to signal that an operation isnot implemented for the given type combination.

Py_RETURN_NOTIMPLEMENTED¶

Properly handle returningPy_NotImplemented from within a Cfunction (that is, increment the reference count of NotImplemented andreturn it).

intPyObject_Print(PyObject *o, FILE *fp, int flags)¶

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

intPyObject_HasAttr(PyObject *o,PyObject *attr_name)¶

Returns1 ifo has the attributeattr_name, and0 otherwise. Thisis equivalent to the Python expressionhasattr(o,attr_name). This functionalways succeeds.

Note that exceptions which occur while calling__getattr__() and__getattribute__() methods will get suppressed.To get error reporting usePyObject_GetAttr() instead.

intPyObject_HasAttrString(PyObject *o, const char *attr_name)¶

Returns1 ifo has the attributeattr_name, and0 otherwise. Thisis equivalent to the Python expressionhasattr(o,attr_name). This functionalways succeeds.

Note that exceptions which occur while calling__getattr__() and__getattribute__() methods and creating a temporary string objectwill get suppressed.To get error reporting usePyObject_GetAttrString() instead.

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

Return value: New reference.

Retrieve an attribute namedattr_name from objecto. Returns the attributevalue on success, orNULL on failure. This is the equivalent of the Pythonexpressiono.attr_name.

PyObject*PyObject_GetAttrString(PyObject *o, const char *attr_name)¶

Return value: New reference.

Retrieve an attribute namedattr_name from objecto. Returns the attributevalue on success, orNULL on failure. This is the equivalent of the Pythonexpressiono.attr_name.

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

Return value: New reference.

Generic attribute getter function that is meant to be put into a typeobject’stp_getattro slot. It looks for a descriptor in the dictionaryof 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-datadescriptors don’t. Otherwise, anAttributeError is raised.

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

Set the value of the attribute namedattr_name, for objecto, to the valuev. Raise an exception and return-1 on failure;return0 on success. This is the equivalent of the Python statemento.attr_name=v.

Ifv isNULL, the attribute is deleted, however this feature isdeprecated in favour of usingPyObject_DelAttr().

intPyObject_SetAttrString(PyObject *o, const char *attr_name,PyObject *v)¶

Set the value of the attribute namedattr_name, for objecto, to the valuev. Raise an exception and return-1 on failure;return0 on success. This is the equivalent of the Python statemento.attr_name=v.

Ifv isNULL, the attribute is deleted, however this feature isdeprecated in favour of usingPyObject_DelAttrString().

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

Generic attribute setter and deleter function that is meantto be put into a type object’stp_setattroslot. It looks for a data descriptor in thedictionary of classes in the object’s MRO, and if found it takes preferenceover setting or deleting the attribute in the instance dictionary. Otherwise, theattribute is set or deleted in the object’s__dict__ (if present).On success,0 is returned, otherwise anAttributeErroris raised and-1 is returned.

intPyObject_DelAttr(PyObject *o,PyObject *attr_name)¶

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

intPyObject_DelAttrString(PyObject *o, const char *attr_name)¶

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

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

Return value: New reference.

A generic implementation for the getter of a__dict__ descriptor. Itcreates the dictionary if necessary.

New in version 3.3.

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

A generic implementation for the setter of a__dict__ descriptor. Thisimplementation does not allow the dictionary to be deleted.

New in version 3.3.

PyObject*PyObject_RichCompare(PyObject *o1,PyObject *o2, int opid)¶

Return value: New reference.

Compare the values ofo1 ando2 using 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 ofthe Python expressiono1opo2, whereop is the operator correspondingtoopid. Returns the value of the comparison on success, orNULL on failure.

intPyObject_RichCompareBool(PyObject *o1,PyObject *o2, int opid)¶

Compare the values ofo1 ando2 using the operation specified byopid,which must be one ofPy_LT,Py_LE,Py_EQ,Py_NE,Py_GT, orPy_GE, corresponding to<,<=,==,!=,>, or>= respectively. Returns-1 on error,0 if the result is false,1 otherwise. This is the equivalent of thePython expressiono1opo2, whereop is the operator corresponding toopid.

PyObject*PyObject_Repr(PyObject *o)¶

Return value: New reference.

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

Changed in version 3.4:This function now includes a debug assertion to help ensure that itdoes not silently discard an active exception.

PyObject*PyObject_ASCII(PyObject *o)¶

Return value: New reference.

AsPyObject_Repr(), compute a string representation of objecto, butescape the non-ASCII characters in the string returned byPyObject_Repr() with\x,\u or\U escapes. This generatesa 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.

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

Changed in version 3.4:This function now includes a debug assertion to help ensure that itdoes not silently discard an active exception.

PyObject*PyObject_Bytes(PyObject *o)¶

Return value: New reference.

Compute a bytes representation of objecto.NULL is returned onfailure and a bytes object on success. This is equivalent to the Pythonexpressionbytes(o), wheno is not an integer. Unlikebytes(o),a TypeError is raised wheno is an integer instead of a zero-initializedbytes object.

intPyObject_IsSubclass(PyObject *derived,PyObject *cls)¶

Return1 if the classderived is identical to or derived from the classcls, otherwise return0. In case of an error, return-1.

Ifcls is a tuple, the check will be done against every entry incls.The result will be1 when at least one of the checks returns1,otherwise it will be0.

Ifcls has a__subclasscheck__() method, it will be called todetermine the subclass status as described inPEP 3119. Otherwise,derived is a subclass ofcls if it is a direct or indirect subclass,i.e. contained incls.__mro__.

Normally only class objects, i.e. instances oftype or a derivedclass, are considered classes. However, objects can override this by havinga__bases__ attribute (which must be a tuple of base classes).

intPyObject_IsInstance(PyObject *inst,PyObject *cls)¶

Return1 ifinst is an instance of the classcls or a subclass ofcls, or0 if not. On error, returns-1 and sets an exception.

Ifcls is a tuple, the check will be done against every entry incls.The result will be1 when at least one of the checks returns1,otherwise it will be0.

Ifcls has a__instancecheck__() method, it will be called todetermine the subclass status as described inPEP 3119. Otherwise,instis an instance ofcls if its class is a subclass ofcls.

An instanceinst can override what is considered its class by having a__class__ attribute.

An objectcls can override if it is considered a class, and what its baseclasses are, by having a__bases__ attribute (which must be a tupleof base classes).

intPyCallable_Check(PyObject *o)¶

Determine if the objecto is callable. Return1 if the object is callableand0 otherwise. This function always succeeds.

PyObject*PyObject_Call(PyObject *callable,PyObject *args,PyObject *kwargs)¶

Return value: New reference.

Call a callable Python objectcallable, with arguments given by thetupleargs, and named arguments given by the dictionarykwargs.

args must not beNULL, use an empty tuple if no arguments are needed.If no named arguments are needed,kwargs can beNULL.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This is the equivalent of the Python expression:callable(*args,**kwargs).

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

Return value: New reference.

Call a callable Python objectcallable, with arguments given by thetupleargs. If no arguments are needed, thenargs can beNULL.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This is the equivalent of the Python expression:callable(*args).

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

Return value: New reference.

Call a callable Python objectcallable, with a variable number of C arguments.The C arguments are described using aPy_BuildValue() style formatstring. The format can beNULL, indicating that no arguments are provided.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This is the equivalent of the Python expression:callable(*args).

Note that if you only passPyObject* args,PyObject_CallFunctionObjArgs() is a faster alternative.

Changed in version 3.4:The type offormat was changed fromchar*.

PyObject*PyObject_CallMethod(PyObject *obj, const char *name, const char *format, ...)¶

Return value: New reference.

Call the method namedname of objectobj with a variable number of Carguments. The C arguments are described by aPy_BuildValue() formatstring that should produce a tuple.

The format can beNULL, indicating that no arguments are provided.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This is the equivalent of the Python expression:obj.name(arg1,arg2,...).

Note that if you only passPyObject* args,PyObject_CallMethodObjArgs() is a faster alternative.

Changed in version 3.4:The types ofname andformat were changed fromchar*.

PyObject*PyObject_CallFunctionObjArgs(PyObject *callable, ...)¶

Return value: New reference.

Call a callable Python objectcallable, with a variable number ofPyObject* arguments. The arguments are provided as a variable numberof parameters followed byNULL.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This is the equivalent of the Python expression:callable(arg1,arg2,...).

PyObject*PyObject_CallMethodObjArgs(PyObject *obj,PyObject *name, ...)¶

Return value: New reference.

Calls a method of the Python objectobj, where the name of the method is given as aPython string object inname. It is called with a variable number ofPyObject* arguments. The arguments are provided as a variable numberof parameters followed byNULL.

Return the result of the call on success, or raise an exception and returnNULL on failure.

PyObject*_PyObject_Vectorcall(PyObject *callable,PyObject *const *args, size_t nargsf,PyObject *kwnames)¶

Call a callable Python objectcallable, usingvectorcall if possible.

args is a C array with the positional arguments.

nargsf is the number of positional arguments plus optionally the flagPY_VECTORCALL_ARGUMENTS_OFFSET (see below).To get actual number of arguments, usePyVectorcall_NARGS(nargsf).

kwnames can be eitherNULL (no keyword arguments) or a tuple of keywordnames. In the latter case, the values of the keyword arguments are storedinargs after the positional arguments.The number of keyword arguments does not influencenargsf.

kwnames must contain only objects of typestr (not a subclass),and all keys must be unique.

Return the result of the call on success, or raise an exception and returnNULL on failure.

This uses the vectorcall protocol if the callable supports it;otherwise, the arguments are converted to usetp_call.

Note

This function is provisional and expected to become public in Python 3.9,with a different name and, possibly, changed semantics.If you use the function, plan for updating your code for Python 3.9.

New in version 3.8.

PY_VECTORCALL_ARGUMENTS_OFFSET¶

If set in a vectorcallnargsf argument, the callee is allowed totemporarily changeargs[-1]. In other words,args points toargument 1 (not 0) in the allocated vector.The callee must restore the value ofargs[-1] before returning.

Whenever they can do so cheaply (without additional allocation), callersare encouraged to usePY_VECTORCALL_ARGUMENTS_OFFSET.Doing so will allow callables such as bound methods to make their onwardcalls (which include a prependedself argument) cheaply.

New in version 3.8.

Py_ssize_tPyVectorcall_NARGS(size_t nargsf)¶

Given a vectorcallnargsf argument, return the actual number ofarguments.Currently equivalent tonargsf&~PY_VECTORCALL_ARGUMENTS_OFFSET.

New in version 3.8.

PyObject*_PyObject_FastCallDict(PyObject *callable,PyObject *const *args, size_t nargsf,PyObject *kwdict)¶

Same as_PyObject_Vectorcall() except that the keyword argumentsare passed as a dictionary inkwdict. This may beNULL if thereare no keyword arguments.

For callables supportingvectorcall,the arguments are internally converted to the vectorcall convention.Therefore, this function adds some overhead compared to_PyObject_Vectorcall().It should only be used if the caller already has a dictionary ready to use.

Note

This function is provisional and expected to become public in Python 3.9,with a different name and, possibly, changed semantics.If you use the function, plan for updating your code for Python 3.9.

New in version 3.8.

Py_hash_tPyObject_Hash(PyObject *o)¶

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 sizeas Py_ssize_t.

Py_hash_tPyObject_HashNotImplemented(PyObject *o)¶

Set aTypeError indicating thattype(o) is not hashable and return-1.This function receives special treatment when stored in atp_hash slot,allowing a type to explicitly indicate to the interpreter that it is nothashable.

intPyObject_IsTrue(PyObject *o)¶

Returns1 if the objecto is considered to be true, and0 otherwise.This is equivalent to the Python expressionnotnoto. On failure, return-1.

intPyObject_Not(PyObject *o)¶

Returns0 if the objecto is considered to be true, and1 otherwise.This is equivalent to the Python expressionnoto. On failure, return-1.

PyObject*PyObject_Type(PyObject *o)¶

Return value: New reference.

Wheno is non-NULL, returns a type object corresponding to the object typeof objecto. On failure, raisesSystemError and returnsNULL. Thisis equivalent to the Python expressiontype(o). This function increments thereference count of the return value. There’s really no reason to use thisfunction instead of the common expressiono->ob_type, which returns apointer of typePyTypeObject*, except when the incremented referencecount is needed.

intPyObject_TypeCheck(PyObject *o,PyTypeObject *type)¶

Return true if the objecto is of typetype or a subtype oftype. Bothparameters must be non-NULL.

Py_ssize_tPyObject_Size(PyObject *o)¶

Py_ssize_tPyObject_Length(PyObject *o)¶

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

Py_ssize_tPyObject_LengthHint(PyObject *o, Py_ssize_t default)¶

Return an estimated length for the objecto. First try to return itsactual length, then an estimate using__length_hint__(), andfinally return the default value. On error return-1. This is theequivalent to the Python expressionoperator.length_hint(o,default).

New in version 3.4.

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

Return value: New reference.

Return element ofo corresponding to the objectkey orNULL on failure.This is the equivalent of the Python expressiono[key].

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

Map the objectkey to the valuev. Raise an exception andreturn-1 on failure; return0 on success. This is theequivalent of the Python statemento[key]=v. This functiondoesnot steal a reference tov.

intPyObject_DelItem(PyObject *o,PyObject *key)¶

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

PyObject*PyObject_Dir(PyObject *o)¶

Return value: New reference.

This is equivalent to the Python expressiondir(o), returning a (possiblyempty) list of strings appropriate for the object argument, orNULL if therewas an error. If the argument isNULL, this is like the Pythondir(),returning the names of the current locals; in this case, if no execution frameis active thenNULL is returned butPyErr_Occurred() will return false.

PyObject*PyObject_GetIter(PyObject *o)¶

Return value: New reference.

This is equivalent to the Python expressioniter(o). It returns a newiterator for the object argument, or the object itself if the object is alreadyan iterator. RaisesTypeError and returnsNULL if the object cannot beiterated.