\chapter{Abstract Objects Layer \label{abstract}} The functions in this chapter interact with Python objects regardlessof their type, or with wide classes of object types (e.g. allnumerical types, or all sequence types). When used on object typesfor which they do not apply, they will raise a Python exception. It is not possible to use these functions on objects that are not properlyinitialized, such as a list object that has been created by\cfunction{PyList_New()}, but whose items have not been set to somenon-\code{NULL} value yet. \section{Object Protocol \label{object}} \begin{cfuncdesc}{int}{PyObject_Print}{PyObject *o, FILE *fp, int flags} Print an object \var{o}, on file \var{fp}. Returns \code{-1} on error. The flags argument is used to enable certain printing options. The only option currently supported is \constant{Py_PRINT_RAW}; if given, the \function{str()} of the object is written instead of the \function{repr()}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttrString}{PyObject *o, const char *attr_name} Returns \code{1} if \var{o} has the attribute \var{attr_name}, and \code{0} otherwise. This is equivalent to the Python expression \samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttrString}{PyObject *o, const char *attr_name} Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}.\var{attr_name}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttr}{PyObject *o, PyObject *attr_name} Returns \code{1} if \var{o} has the attribute \var{attr_name}, and \code{0} otherwise. This is equivalent to the Python expression \samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttr}{PyObject *o, PyObject *attr_name} Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}.\var{attr_name}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttrString}{PyObject *o, const char *attr_name, PyObject *v} Set the value of the attribute named \var{attr_name}, for object \var{o}, to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = \var{v}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttr}{PyObject *o, PyObject *attr_name, PyObject *v} Set the value of the attribute named \var{attr_name}, for object \var{o}, to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = \var{v}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttrString}{PyObject *o, const char *attr_name} Delete attribute named \var{attr_name}, for object \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement: \samp{del \var{o}.\var{attr_name}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttr}{PyObject *o, PyObject *attr_name} Delete attribute named \var{attr_name}, for object \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{del \var{o}.\var{attr_name}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_RichCompare}{PyObject *o1, PyObject *o2, int opid} Compare the values of \var{o1} and \var{o2} using the operation specified by \var{opid}, which must be one of \constant{Py_LT}, \constant{Py_LE}, \constant{Py_EQ}, \constant{Py_NE}, \constant{Py_GT}, or \constant{Py_GE}, corresponding to \code{<}, \code{<=}, \code{==}, \code{!=}, \code{>}, or \code{>=} respectively. This is the equivalent of the Python expression \samp{\var{o1} op \var{o2}}, where \code{op} is the operator corresponding to \var{opid}. Returns the value of the comparison on success, or \NULL{} on failure.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_RichCompareBool}{PyObject *o1, PyObject *o2, int opid} Compare the values of \var{o1} and \var{o2} using the operation specified by \var{opid}, which must be one of \constant{Py_LT}, \constant{Py_LE}, \constant{Py_EQ}, \constant{Py_NE}, \constant{Py_GT}, or \constant{Py_GE}, corresponding to \code{<}, \code{<=}, \code{==}, \code{!=}, \code{>}, or \code{>=} respectively. Returns \code{-1} on error, \code{0} if the result is false, \code{1} otherwise. This is the equivalent of the Python expression \samp{\var{o1} op \var{o2}}, where \code{op} is the operator corresponding to \var{opid}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Cmp}{PyObject *o1, PyObject *o2, int *result} Compare the values of \var{o1} and \var{o2} using a routine provided by \var{o1}, if one exists, otherwise with a routine provided by \var{o2}. The result of the comparison is returned in \var{result}. Returns \code{-1} on failure. This is the equivalent of the Python statement\bifuncindex{cmp} \samp{\var{result} = cmp(\var{o1}, \var{o2})}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Compare}{PyObject *o1, PyObject *o2} Compare the values of \var{o1} and \var{o2} using a routine provided by \var{o1}, if one exists, otherwise with a routine provided by \var{o2}. Returns the result of the comparison on success. On error, the value returned is undefined; use \cfunction{PyErr_Occurred()} to detect an error. This is equivalent to the Python expression\bifuncindex{cmp} \samp{cmp(\var{o1}, \var{o2})}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Repr}{PyObject *o} Compute a string representation of object \var{o}. Returns the string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{repr(\var{o})}. Called by the \function{repr()}\bifuncindex{repr} built-in function and by reverse quotes.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Str}{PyObject *o} Compute a string representation of object \var{o}. Returns the string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{str(\var{o})}. Called by the \function{str()}\bifuncindex{str} built-in function and by the \keyword{print} statement.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Unicode}{PyObject *o} Compute a Unicode string representation of object \var{o}. Returns the Unicode string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{unicode(\var{o})}. Called by the \function{unicode()}\bifuncindex{unicode} built-in function.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsInstance}{PyObject *inst, PyObject *cls} Returns \code{1} if \var{inst} is an instance of the class \var{cls} or a subclass of \var{cls}, or \code{0} if not. On error, returns \code{-1} and sets an exception. If \var{cls} is a type object rather than a class object, \cfunction{PyObject_IsInstance()} returns \code{1} if \var{inst} is of type \var{cls}. If \var{cls} is a tuple, the check will be done against every entry in \var{cls}. The result will be \code{1} when at least one of the checks returns \code{1}, otherwise it will be \code{0}. If \var{inst} is not a class instance and \var{cls} is neither a type object, nor a class object, nor a tuple, \var{inst} must have a \member{__class__} attribute --- the class relationship of the value of that attribute with \var{cls} will be used to determine the result of this function. \versionadded{2.1} \versionchanged[Support for a tuple as the second argument added]{2.2}\end{cfuncdesc} Subclass determination is done in a fairly straightforward way, butincludes a wrinkle that implementors of extensions to the class systemmay want to be aware of. If \class{A} and \class{B} are classobjects, \class{B} is a subclass of \class{A} if it inherits from\class{A} either directly or indirectly. If either is not a classobject, a more general mechanism is used to determine the classrelationship of the two objects. When testing if \var{B} is asubclass of \var{A}, if \var{A} is \var{B},\cfunction{PyObject_IsSubclass()} returns true. If \var{A} and\var{B} are different objects, \var{B}'s \member{__bases__} attributeis searched in a depth-first fashion for \var{A} --- the presence ofthe \member{__bases__} attribute is considered sufficient for thisdetermination. \begin{cfuncdesc}{int}{PyObject_IsSubclass}{PyObject *derived, PyObject *cls} Returns \code{1} if the class \var{derived} is identical to or derived from the class \var{cls}, otherwise returns \code{0}. In case of an error, returns \code{-1}. If \var{cls} is a tuple, the check will be done against every entry in \var{cls}. The result will be \code{1} when at least one of the checks returns \code{1}, otherwise it will be \code{0}. If either \var{derived} or \var{cls} is not an actual class object (or tuple), this function uses the generic algorithm described above. \versionadded{2.1} \versionchanged[Older versions of Python did not support a tuple as the second argument]{2.3}\end{cfuncdesc} \begin{cfuncdesc}{int}{PyCallable_Check}{PyObject *o} Determine if the object \var{o} is callable. Return \code{1} if the object is callable and \code{0} otherwise. This function always succeeds.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Call}{PyObject *callable_object, PyObject *args, PyObject *kw} Call a callable Python object \var{callable_object}, with arguments given by the tuple \var{args}, and named arguments given by the dictionary \var{kw}. If no named arguments are needed, \var{kw} may be \NULL{}. \var{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 \samp{apply(\var{callable_object}, \var{args}, \var{kw})} or \samp{\var{callable_object}(*\var{args}, **\var{kw})}. \bifuncindex{apply} \versionadded{2.2}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallObject}{PyObject *callable_object, PyObject *args} Call a callable Python object \var{callable_object}, with arguments given by the tuple \var{args}. If no arguments are needed, then \var{args} may be \NULL. Returns the result of the call on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{apply(\var{callable_object}, \var{args})} or \samp{\var{callable_object}(*\var{args})}. \bifuncindex{apply}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallFunction}{PyObject *callable, char *format, \moreargs} Call a callable Python object \var{callable}, with a variable number of C arguments. The C arguments are described using a \cfunction{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 \samp{apply(\var{callable}, \var{args})} or \samp{\var{callable}(*\var{args})}. Note that if you only pass \ctype{PyObject *} args, \cfunction{PyObject_CallFunctionObjArgs} is a faster alternative. \bifuncindex{apply}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallMethod}{PyObject *o, char *method, char *format, \moreargs} Call the method named \var{method} of object \var{o} with a variable number of C arguments. The C arguments are described by a \cfunction{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 \samp{\var{o}.\var{method}(\var{args})}. Note that if you only pass \ctype{PyObject *} args, \cfunction{PyObject_CallMethodObjArgs} is a faster alternative.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallFunctionObjArgs}{PyObject *callable, \moreargs, \code{NULL}} Call a callable Python object \var{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}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallMethodObjArgs}{PyObject *o, PyObject *name, \moreargs, \code{NULL}} Calls a method of the object \var{o}, where the name of the method is given as a Python string object in \var{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}\end{cfuncdesc} \begin{cfuncdesc}{long}{PyObject_Hash}{PyObject *o} Compute and return the hash value of an object \var{o}. On failure, return \code{-1}. This is the equivalent of the Python expression \samp{hash(\var{o})}.\bifuncindex{hash}\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsTrue}{PyObject *o} Returns \code{1} if the object \var{o} is considered to be true, and \code{0} otherwise. This is equivalent to the Python expression \samp{not not \var{o}}. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Not}{PyObject *o} Returns \code{0} if the object \var{o} is considered to be true, and \code{1} otherwise. This is equivalent to the Python expression \samp{not \var{o}}. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Type}{PyObject *o} When \var{o} is non-\NULL, returns a type object corresponding to the object type of object \var{o}. On failure, raises \exception{SystemError} and returns \NULL. This is equivalent to the Python expression \code{type(\var{o})}.\bifuncindex{type} This function increments the reference count of the return value. There's really no reason to use this function instead of the common expression \code{\var{o}->ob_type}, which returns a pointer of type \ctype{PyTypeObject*}, except when the incremented reference count is needed.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_TypeCheck}{PyObject *o, PyTypeObject *type} Return true if the object \var{o} is of type \var{type} or a subtype of \var{type}. Both parameters must be non-\NULL. \versionadded{2.2}\end{cfuncdesc} \begin{cfuncdesc}{Py_ssize_t}{PyObject_Length}{PyObject *o}\cfuncline{Py_ssize_t}{PyObject_Size}{PyObject *o} Return the length of object \var{o}. If the object \var{o} provides either the sequence and mapping protocols, the sequence length is returned. On error, \code{-1} is returned. This is the equivalent to the Python expression \samp{len(\var{o})}.\bifuncindex{len}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetItem}{PyObject *o, PyObject *key} Return element of \var{o} corresponding to the object \var{key} or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}[\var{key}]}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetItem}{PyObject *o, PyObject *key, PyObject *v} Map the object \var{key} to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}[\var{key}] = \var{v}}.\end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelItem}{PyObject *o, PyObject *key} Delete the mapping for \var{key} from \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{del \var{o}[\var{key}]}.\end{cfuncdesc} \begin{cfuncdesc}{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 \method{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 \code{-1} on failure.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Dir}{PyObject *o} This is equivalent to the Python expression \samp{dir(\var{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 \samp{dir()}, returning the names of the current locals; in this case, if no execution frame is active then \NULL{} is returned but \cfunction{PyErr_Occurred()} will return false.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetIter}{PyObject *o} This is equivalent to the Python expression \samp{iter(\var{o})}. It returns a new iterator for the object argument, or the object itself if the object is already an iterator. Raises \exception{TypeError} and returns \NULL{} if the object cannot be iterated.\end{cfuncdesc} \section{Number Protocol \label{number}} \begin{cfuncdesc}{int}{PyNumber_Check}{PyObject *o} Returns \code{1} if the object \var{o} provides numeric protocols, and false otherwise. This function always succeeds.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Add}{PyObject *o1, PyObject *o2} Returns the result of adding \var{o1} and \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} + \var{o2}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Subtract}{PyObject *o1, PyObject *o2} Returns the result of subtracting \var{o2} from \var{o1}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} - \var{o2}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Multiply}{PyObject *o1, PyObject *o2} Returns the result of multiplying \var{o1} and \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} * \var{o2}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divide}{PyObject *o1, PyObject *o2} Returns the result of dividing \var{o1} by \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} / \var{o2}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_FloorDivide}{PyObject *o1, PyObject *o2} Return the floor of \var{o1} divided by \var{o2}, or \NULL{} on failure. This is equivalent to the ``classic'' division of integers. \versionadded{2.2}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_TrueDivide}{PyObject *o1, PyObject *o2} Return a reasonable approximation for the mathematical value of \var{o1} divided by \var{o2}, or \NULL{} on failure. The return value is ``approximate'' because binary floating point numbers are approximate; it is not possible to represent all real numbers in base two. This function can return a floating point value when passed two integers. \versionadded{2.2}\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Remainder}{PyObject *o1, PyObject *o2} Returns the remainder of dividing \var{o1} by \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} \%\ \var{o2}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divmod}{PyObject *o1, PyObject *o2} See the built-in function \function{divmod()}\bifuncindex{divmod}. Returns \NULL{} on failure. This is the equivalent of the Python expression \samp{divmod(\var{o1}, \var{o2})}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Power}{PyObject *o1, PyObject *o2, PyObject *o3} See the built-in function \function{pow()}\bifuncindex{pow}. Returns \NULL{} on failure. This is the equivalent of the Python expression \samp{pow(\var{o1}, \var{o2}, \var{o3})}, where \var{o3} is optional. If \var{o3} is to be ignored, pass \cdata{Py_None} in its place (passing \NULL{} for \var{o3} would cause an illegal memory access).\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Negative}{PyObject *o} Returns the negation of \var{o} on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{-\var{o}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Positive}{PyObject *o} Returns \var{o} on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{+\var{o}}.\end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Absolute}{PyObject *o}Lines 1–500 of 1057. Load more
\chapter{Abstract Objects Layer \label{abstract}} The functions in this chapter interact with Python objects regardless of their type, or with wide classes of object types (e.g. all numerical types, or all sequence types). When used on object types for which they do not apply, they will raise a Python exception. It is not possible to use these functions on objects that are not properly initialized, such as a list object that has been created by \cfunction{PyList_New()}, but whose items have not been set to some non-\code{NULL} value yet. \section{Object Protocol \label{object}} \begin{cfuncdesc}{int}{PyObject_Print}{PyObject *o, FILE *fp, int flags} Print an object \var{o}, on file \var{fp}. Returns \code{-1} on error. The flags argument is used to enable certain printing options. The only option currently supported is \constant{Py_PRINT_RAW}; if given, the \function{str()} of the object is written instead of the \function{repr()}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttrString}{PyObject *o, const char *attr_name} Returns \code{1} if \var{o} has the attribute \var{attr_name}, and \code{0} otherwise. This is equivalent to the Python expression \samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttrString}{PyObject *o, const char *attr_name} Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttr}{PyObject *o, PyObject *attr_name} Returns \code{1} if \var{o} has the attribute \var{attr_name}, and \code{0} otherwise. This is equivalent to the Python expression \samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttr}{PyObject *o, PyObject *attr_name} Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttrString}{PyObject *o, const char *attr_name, PyObject *v} Set the value of the attribute named \var{attr_name}, for object \var{o}, to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttr}{PyObject *o, PyObject *attr_name, PyObject *v} Set the value of the attribute named \var{attr_name}, for object \var{o}, to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttrString}{PyObject *o, const char *attr_name} Delete attribute named \var{attr_name}, for object \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement: \samp{del \var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttr}{PyObject *o, PyObject *attr_name} Delete attribute named \var{attr_name}, for object \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{del \var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_RichCompare}{PyObject *o1, PyObject *o2, int opid} Compare the values of \var{o1} and \var{o2} using the operation specified by \var{opid}, which must be one of \constant{Py_LT}, \constant{Py_LE}, \constant{Py_EQ}, \constant{Py_NE}, \constant{Py_GT}, or \constant{Py_GE}, corresponding to \code{<}, \code{<=}, \code{==}, \code{!=}, \code{>}, or \code{>=} respectively. This is the equivalent of the Python expression \samp{\var{o1} op \var{o2}}, where \code{op} is the operator corresponding to \var{opid}. Returns the value of the comparison on success, or \NULL{} on failure. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_RichCompareBool}{PyObject *o1, PyObject *o2, int opid} Compare the values of \var{o1} and \var{o2} using the operation specified by \var{opid}, which must be one of \constant{Py_LT}, \constant{Py_LE}, \constant{Py_EQ}, \constant{Py_NE}, \constant{Py_GT}, or \constant{Py_GE}, corresponding to \code{<}, \code{<=}, \code{==}, \code{!=}, \code{>}, or \code{>=} respectively. Returns \code{-1} on error, \code{0} if the result is false, \code{1} otherwise. This is the equivalent of the Python expression \samp{\var{o1} op \var{o2}}, where \code{op} is the operator corresponding to \var{opid}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Cmp}{PyObject *o1, PyObject *o2, int *result} Compare the values of \var{o1} and \var{o2} using a routine provided by \var{o1}, if one exists, otherwise with a routine provided by \var{o2}. The result of the comparison is returned in \var{result}. Returns \code{-1} on failure. This is the equivalent of the Python statement\bifuncindex{cmp} \samp{\var{result} = cmp(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Compare}{PyObject *o1, PyObject *o2} Compare the values of \var{o1} and \var{o2} using a routine provided by \var{o1}, if one exists, otherwise with a routine provided by \var{o2}. Returns the result of the comparison on success. On error, the value returned is undefined; use \cfunction{PyErr_Occurred()} to detect an error. This is equivalent to the Python expression\bifuncindex{cmp} \samp{cmp(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Repr}{PyObject *o} Compute a string representation of object \var{o}. Returns the string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{repr(\var{o})}. Called by the \function{repr()}\bifuncindex{repr} built-in function and by reverse quotes. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Str}{PyObject *o} Compute a string representation of object \var{o}. Returns the string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{str(\var{o})}. Called by the \function{str()}\bifuncindex{str} built-in function and by the \keyword{print} statement. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Unicode}{PyObject *o} Compute a Unicode string representation of object \var{o}. Returns the Unicode string representation on success, \NULL{} on failure. This is the equivalent of the Python expression \samp{unicode(\var{o})}. Called by the \function{unicode()}\bifuncindex{unicode} built-in function. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsInstance}{PyObject *inst, PyObject *cls} Returns \code{1} if \var{inst} is an instance of the class \var{cls} or a subclass of \var{cls}, or \code{0} if not. On error, returns \code{-1} and sets an exception. If \var{cls} is a type object rather than a class object, \cfunction{PyObject_IsInstance()} returns \code{1} if \var{inst} is of type \var{cls}. If \var{cls} is a tuple, the check will be done against every entry in \var{cls}. The result will be \code{1} when at least one of the checks returns \code{1}, otherwise it will be \code{0}. If \var{inst} is not a class instance and \var{cls} is neither a type object, nor a class object, nor a tuple, \var{inst} must have a \member{__class__} attribute --- the class relationship of the value of that attribute with \var{cls} will be used to determine the result of this function. \versionadded{2.1} \versionchanged[Support for a tuple as the second argument added]{2.2} \end{cfuncdesc} 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 \var{B} is a subclass of \var{A}, if \var{A} is \var{B}, \cfunction{PyObject_IsSubclass()} returns true. If \var{A} and \var{B} are different objects, \var{B}'s \member{__bases__} attribute is searched in a depth-first fashion for \var{A} --- the presence of the \member{__bases__} attribute is considered sufficient for this determination. \begin{cfuncdesc}{int}{PyObject_IsSubclass}{PyObject *derived, PyObject *cls} Returns \code{1} if the class \var{derived} is identical to or derived from the class \var{cls}, otherwise returns \code{0}. In case of an error, returns \code{-1}. If \var{cls} is a tuple, the check will be done against every entry in \var{cls}. The result will be \code{1} when at least one of the checks returns \code{1}, otherwise it will be \code{0}. If either \var{derived} or \var{cls} is not an actual class object (or tuple), this function uses the generic algorithm described above. \versionadded{2.1} \versionchanged[Older versions of Python did not support a tuple as the second argument]{2.3} \end{cfuncdesc} \begin{cfuncdesc}{int}{PyCallable_Check}{PyObject *o} Determine if the object \var{o} is callable. Return \code{1} if the object is callable and \code{0} otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Call}{PyObject *callable_object, PyObject *args, PyObject *kw} Call a callable Python object \var{callable_object}, with arguments given by the tuple \var{args}, and named arguments given by the dictionary \var{kw}. If no named arguments are needed, \var{kw} may be \NULL{}. \var{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 \samp{apply(\var{callable_object}, \var{args}, \var{kw})} or \samp{\var{callable_object}(*\var{args}, **\var{kw})}. \bifuncindex{apply} \versionadded{2.2} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallObject}{PyObject *callable_object, PyObject *args} Call a callable Python object \var{callable_object}, with arguments given by the tuple \var{args}. If no arguments are needed, then \var{args} may be \NULL. Returns the result of the call on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{apply(\var{callable_object}, \var{args})} or \samp{\var{callable_object}(*\var{args})}. \bifuncindex{apply} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallFunction}{PyObject *callable, char *format, \moreargs} Call a callable Python object \var{callable}, with a variable number of C arguments. The C arguments are described using a \cfunction{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 \samp{apply(\var{callable}, \var{args})} or \samp{\var{callable}(*\var{args})}. Note that if you only pass \ctype{PyObject *} args, \cfunction{PyObject_CallFunctionObjArgs} is a faster alternative. \bifuncindex{apply} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallMethod}{PyObject *o, char *method, char *format, \moreargs} Call the method named \var{method} of object \var{o} with a variable number of C arguments. The C arguments are described by a \cfunction{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 \samp{\var{o}.\var{method}(\var{args})}. Note that if you only pass \ctype{PyObject *} args, \cfunction{PyObject_CallMethodObjArgs} is a faster alternative. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallFunctionObjArgs}{PyObject *callable, \moreargs, \code{NULL}} Call a callable Python object \var{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} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallMethodObjArgs}{PyObject *o, PyObject *name, \moreargs, \code{NULL}} Calls a method of the object \var{o}, where the name of the method is given as a Python string object in \var{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} \end{cfuncdesc} \begin{cfuncdesc}{long}{PyObject_Hash}{PyObject *o} Compute and return the hash value of an object \var{o}. On failure, return \code{-1}. This is the equivalent of the Python expression \samp{hash(\var{o})}.\bifuncindex{hash} \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsTrue}{PyObject *o} Returns \code{1} if the object \var{o} is considered to be true, and \code{0} otherwise. This is equivalent to the Python expression \samp{not not \var{o}}. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Not}{PyObject *o} Returns \code{0} if the object \var{o} is considered to be true, and \code{1} otherwise. This is equivalent to the Python expression \samp{not \var{o}}. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Type}{PyObject *o} When \var{o} is non-\NULL, returns a type object corresponding to the object type of object \var{o}. On failure, raises \exception{SystemError} and returns \NULL. This is equivalent to the Python expression \code{type(\var{o})}.\bifuncindex{type} This function increments the reference count of the return value. There's really no reason to use this function instead of the common expression \code{\var{o}->ob_type}, which returns a pointer of type \ctype{PyTypeObject*}, except when the incremented reference count is needed. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_TypeCheck}{PyObject *o, PyTypeObject *type} Return true if the object \var{o} is of type \var{type} or a subtype of \var{type}. Both parameters must be non-\NULL. \versionadded{2.2} \end{cfuncdesc} \begin{cfuncdesc}{Py_ssize_t}{PyObject_Length}{PyObject *o} \cfuncline{Py_ssize_t}{PyObject_Size}{PyObject *o} Return the length of object \var{o}. If the object \var{o} provides either the sequence and mapping protocols, the sequence length is returned. On error, \code{-1} is returned. This is the equivalent to the Python expression \samp{len(\var{o})}.\bifuncindex{len} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetItem}{PyObject *o, PyObject *key} Return element of \var{o} corresponding to the object \var{key} or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetItem}{PyObject *o, PyObject *key, PyObject *v} Map the object \var{key} to the value \var{v}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{\var{o}[\var{key}] = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelItem}{PyObject *o, PyObject *key} Delete the mapping for \var{key} from \var{o}. Returns \code{-1} on failure. This is the equivalent of the Python statement \samp{del \var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{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 \method{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 \code{-1} on failure. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Dir}{PyObject *o} This is equivalent to the Python expression \samp{dir(\var{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 \samp{dir()}, returning the names of the current locals; in this case, if no execution frame is active then \NULL{} is returned but \cfunction{PyErr_Occurred()} will return false. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetIter}{PyObject *o} This is equivalent to the Python expression \samp{iter(\var{o})}. It returns a new iterator for the object argument, or the object itself if the object is already an iterator. Raises \exception{TypeError} and returns \NULL{} if the object cannot be iterated. \end{cfuncdesc} \section{Number Protocol \label{number}} \begin{cfuncdesc}{int}{PyNumber_Check}{PyObject *o} Returns \code{1} if the object \var{o} provides numeric protocols, and false otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Add}{PyObject *o1, PyObject *o2} Returns the result of adding \var{o1} and \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} + \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Subtract}{PyObject *o1, PyObject *o2} Returns the result of subtracting \var{o2} from \var{o1}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} - \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Multiply}{PyObject *o1, PyObject *o2} Returns the result of multiplying \var{o1} and \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} * \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divide}{PyObject *o1, PyObject *o2} Returns the result of dividing \var{o1} by \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} / \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_FloorDivide}{PyObject *o1, PyObject *o2} Return the floor of \var{o1} divided by \var{o2}, or \NULL{} on failure. This is equivalent to the ``classic'' division of integers. \versionadded{2.2} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_TrueDivide}{PyObject *o1, PyObject *o2} Return a reasonable approximation for the mathematical value of \var{o1} divided by \var{o2}, or \NULL{} on failure. The return value is ``approximate'' because binary floating point numbers are approximate; it is not possible to represent all real numbers in base two. This function can return a floating point value when passed two integers. \versionadded{2.2} \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Remainder}{PyObject *o1, PyObject *o2} Returns the remainder of dividing \var{o1} by \var{o2}, or \NULL{} on failure. This is the equivalent of the Python expression \samp{\var{o1} \%\ \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divmod}{PyObject *o1, PyObject *o2} See the built-in function \function{divmod()}\bifuncindex{divmod}. Returns \NULL{} on failure. This is the equivalent of the Python expression \samp{divmod(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Power}{PyObject *o1, PyObject *o2, PyObject *o3} See the built-in function \function{pow()}\bifuncindex{pow}. Returns \NULL{} on failure. This is the equivalent of the Python expression \samp{pow(\var{o1}, \var{o2}, \var{o3})}, where \var{o3} is optional. If \var{o3} is to be ignored, pass \cdata{Py_None} in its place (passing \NULL{} for \var{o3} would cause an illegal memory access). \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Negative}{PyObject *o} Returns the negation of \var{o} on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{-\var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Positive}{PyObject *o} Returns \var{o} on success, or \NULL{} on failure. This is the equivalent of the Python expression \samp{+\var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Absolute}{PyObject *o}