ref: 7186be0424ba65942a13b7706017c6ef4338f219
dir: /sys/src/cmd/python/Doc/api/abstract.tex/
\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}
Returns the absolute value of \var{o}, or \NULL{} on failure. This
is the equivalent of the Python expression \samp{abs(\var{o})}.
\bifuncindex{abs}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Invert}{PyObject *o}
Returns the bitwise 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_Lshift}{PyObject *o1, PyObject *o2}
Returns the result of left shifting \var{o1} by \var{o2} on success,
or \NULL{} on failure. This is the equivalent of the Python
expression \samp{\var{o1} <\code{<} \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Rshift}{PyObject *o1, PyObject *o2}
Returns the result of right shifting \var{o1} by \var{o2} on
success, or \NULL{} on failure. This is the equivalent of the
Python expression \samp{\var{o1} >\code{>} \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_And}{PyObject *o1, PyObject *o2}
Returns the ``bitwise and'' of \var{o1} and \var{o2} on success and
\NULL{} on failure. This is the equivalent of the Python expression
\samp{\var{o1} \&\ \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Xor}{PyObject *o1, PyObject *o2}
Returns the ``bitwise exclusive or'' of \var{o1} by \var{o2} on
success, or \NULL{} on failure. This is the equivalent of the
Python expression \samp{\var{o1} \textasciicircum{} \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Or}{PyObject *o1, PyObject *o2}
Returns the ``bitwise or'' of \var{o1} and \var{o2} on success, or
\NULL{} on failure. This is the equivalent of the Python expression
\samp{\var{o1} | \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceAdd}{PyObject *o1, PyObject *o2}
Returns the result of adding \var{o1} and \var{o2}, or \NULL{} on
failure. The operation is done \emph{in-place} when \var{o1}
supports it. This is the equivalent of the Python statement
\samp{\var{o1} += \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceSubtract}{PyObject *o1,
PyObject *o2}
Returns the result of subtracting \var{o2} from \var{o1}, or \NULL{}
on failure. The operation is done \emph{in-place} when \var{o1}
supports it. This is the equivalent of the Python statement
\samp{\var{o1} -= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceMultiply}{PyObject *o1,
PyObject *o2}
Returns the result of multiplying \var{o1} and \var{o2}, or \NULL{}
on failure. The operation is done \emph{in-place} when \var{o1}
supports it. This is the equivalent of the Python statement
\samp{\var{o1} *= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceDivide}{PyObject *o1,
PyObject *o2}
Returns the result of dividing \var{o1} by \var{o2}, or \NULL{} on
failure. The operation is done \emph{in-place} when \var{o1}
supports it. This is the equivalent of the Python statement
\samp{\var{o1} /= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceFloorDivide}{PyObject *o1,
PyObject *o2}
Returns the mathematical floor of dividing \var{o1} by \var{o2}, or
\NULL{} on failure. The operation is done \emph{in-place} when
\var{o1} supports it. This is the equivalent of the Python
statement \samp{\var{o1} //= \var{o2}}.
\versionadded{2.2}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceTrueDivide}{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. The operation is done \emph{in-place} when
\var{o1} supports it.
\versionadded{2.2}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceRemainder}{PyObject *o1,
PyObject *o2}
Returns the remainder of dividing \var{o1} by \var{o2}, or \NULL{}
on failure. The operation is done \emph{in-place} when \var{o1}
supports it. This is the equivalent of the Python statement
\samp{\var{o1} \%= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlacePower}{PyObject *o1,
PyObject *o2, PyObject *o3}
See the built-in function \function{pow()}.\bifuncindex{pow}
Returns \NULL{} on failure. The operation is done \emph{in-place}
when \var{o1} supports it. This is the equivalent of the Python
statement \samp{\var{o1} **= \var{o2}} when o3 is \cdata{Py_None},
or an in-place variant of \samp{pow(\var{o1}, \var{o2}, \var{o3})}
otherwise. 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_InPlaceLshift}{PyObject *o1,
PyObject *o2}
Returns the result of left shifting \var{o1} by \var{o2} on success,
or \NULL{} on failure. The operation is done \emph{in-place} when
\var{o1} supports it. This is the equivalent of the Python
statement \samp{\var{o1} <\code{<=} \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceRshift}{PyObject *o1,
PyObject *o2}
Returns the result of right shifting \var{o1} by \var{o2} on
success, or \NULL{} on failure. The operation is done
\emph{in-place} when \var{o1} supports it. This is the equivalent
of the Python statement \samp{\var{o1} >>= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceAnd}{PyObject *o1, PyObject *o2}
Returns the ``bitwise and'' of \var{o1} and \var{o2} on success and
\NULL{} on failure. The operation is done \emph{in-place} when
\var{o1} supports it. This is the equivalent of the Python
statement \samp{\var{o1} \&= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceXor}{PyObject *o1, PyObject *o2}
Returns the ``bitwise exclusive or'' of \var{o1} by \var{o2} on
success, or \NULL{} on failure. The operation is done
\emph{in-place} when \var{o1} supports it. This is the equivalent
of the Python statement \samp{\var{o1} \textasciicircum= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_InPlaceOr}{PyObject *o1, PyObject *o2}
Returns the ``bitwise or'' of \var{o1} and \var{o2} on success, or
\NULL{} on failure. The operation is done \emph{in-place} when
\var{o1} supports it. This is the equivalent of the Python
statement \samp{\var{o1} |= \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyNumber_Coerce}{PyObject **p1, PyObject **p2}
This function takes the addresses of two variables of type
\ctype{PyObject*}. If the objects pointed to by \code{*\var{p1}}
and \code{*\var{p2}} have the same type, increment their reference
count and return \code{0} (success). If the objects can be converted
to a common numeric type, replace \code{*p1} and \code{*p2} by their
converted value (with 'new' reference counts), and return \code{0}.
If no conversion is possible, or if some other error occurs, return
\code{-1} (failure) and don't increment the reference counts. The
call \code{PyNumber_Coerce(\&o1, \&o2)} is equivalent to the Python
statement \samp{\var{o1}, \var{o2} = coerce(\var{o1}, \var{o2})}.
\bifuncindex{coerce}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Int}{PyObject *o}
Returns the \var{o} converted to an integer object on success, or
\NULL{} on failure. If the argument is outside the integer range
a long object will be returned instead. This is the equivalent
of the Python expression \samp{int(\var{o})}.\bifuncindex{int}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Long}{PyObject *o}
Returns the \var{o} converted to a long integer object on success,
or \NULL{} on failure. This is the equivalent of the Python
expression \samp{long(\var{o})}.\bifuncindex{long}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Float}{PyObject *o}
Returns the \var{o} converted to a float object on success, or
\NULL{} on failure. This is the equivalent of the Python expression
\samp{float(\var{o})}.\bifuncindex{float}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyNumber_Index}{PyObject *o}
Returns the \var{o} converted to a Python int or long on success or \NULL{}
with a TypeError exception raised on failure.
\versionadded{2.5}
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PyNumber_AsSsize_t}{PyObject *o, PyObject *exc}
Returns \var{o} converted to a Py_ssize_t value if \var{o}
can be interpreted as an integer. If \var{o} can be converted to a Python
int or long but the attempt to convert to a Py_ssize_t value
would raise an \exception{OverflowError}, then the \var{exc} argument
is the type of exception that will be raised (usually \exception{IndexError}
or \exception{OverflowError}). If \var{exc} is \NULL{}, then the exception
is cleared and the value is clipped to \var{PY_SSIZE_T_MIN}
for a negative integer or \var{PY_SSIZE_T_MAX} for a positive integer.
\versionadded{2.5}
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyIndex_Check}{PyObject *o}
Returns True if \var{o} is an index integer (has the nb_index slot of
the tp_as_number structure filled in).
\versionadded{2.5}
\end{cfuncdesc}
\section{Sequence Protocol \label{sequence}}
\begin{cfuncdesc}{int}{PySequence_Check}{PyObject *o}
Return \code{1} if the object provides sequence protocol, and
\code{0} otherwise. This function always succeeds.
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PySequence_Size}{PyObject *o}
Returns the number of objects in sequence \var{o} on success, and
\code{-1} on failure. For objects that do not provide sequence
protocol, this is equivalent to the Python expression
\samp{len(\var{o})}.\bifuncindex{len}
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PySequence_Length}{PyObject *o}
Alternate name for \cfunction{PySequence_Size()}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_Concat}{PyObject *o1, PyObject *o2}
Return the concatenation of \var{o1} and \var{o2} on success, and
\NULL{} on failure. This is the equivalent of the Python
expression \samp{\var{o1} + \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_Repeat}{PyObject *o, Py_ssize_t count}
Return the result of repeating sequence object \var{o} \var{count}
times, or \NULL{} on failure. This is the equivalent of the Python
expression \samp{\var{o} * \var{count}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_InPlaceConcat}{PyObject *o1,
PyObject *o2}
Return the concatenation of \var{o1} and \var{o2} on success, and
\NULL{} on failure. The operation is done \emph{in-place} when
\var{o1} supports it. This is the equivalent of the Python
expression \samp{\var{o1} += \var{o2}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_InPlaceRepeat}{PyObject *o, Py_ssize_t count}
Return the result of repeating sequence object \var{o} \var{count}
times, or \NULL{} on failure. The operation is done \emph{in-place}
when \var{o} supports it. This is the equivalent of the Python
expression \samp{\var{o} *= \var{count}}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_GetItem}{PyObject *o, Py_ssize_t i}
Return the \var{i}th element of \var{o}, or \NULL{} on failure.
This is the equivalent of the Python expression
\samp{\var{o}[\var{i}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_GetSlice}{PyObject *o, Py_ssize_t i1, Py_ssize_t i2}
Return the slice of sequence object \var{o} between \var{i1} and
\var{i2}, or \NULL{} on failure. This is the equivalent of the
Python expression \samp{\var{o}[\var{i1}:\var{i2}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PySequence_SetItem}{PyObject *o, Py_ssize_t i, PyObject *v}
Assign object \var{v} to the \var{i}th element of \var{o}. Returns
\code{-1} on failure. This is the equivalent of the Python
statement \samp{\var{o}[\var{i}] = \var{v}}. This function \emph{does not}
steal a reference to \var{v}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PySequence_DelItem}{PyObject *o, Py_ssize_t i}
Delete the \var{i}th element of object \var{o}. Returns \code{-1}
on failure. This is the equivalent of the Python statement
\samp{del \var{o}[\var{i}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PySequence_SetSlice}{PyObject *o, Py_ssize_t i1,
Py_ssize_t i2, PyObject *v}
Assign the sequence object \var{v} to the slice in sequence object
\var{o} from \var{i1} to \var{i2}. This is the equivalent of the
Python statement \samp{\var{o}[\var{i1}:\var{i2}] = \var{v}}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PySequence_DelSlice}{PyObject *o, Py_ssize_t i1, Py_ssize_t i2}
Delete the slice in sequence object \var{o} from \var{i1} to
\var{i2}. Returns \code{-1} on failure. This is the equivalent of
the Python statement \samp{del \var{o}[\var{i1}:\var{i2}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PySequence_Count}{PyObject *o, PyObject *value}
Return the number of occurrences of \var{value} in \var{o}, that is,
return the number of keys for which \code{\var{o}[\var{key}] ==
\var{value}}. On failure, return \code{-1}. This is equivalent to
the Python expression \samp{\var{o}.count(\var{value})}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PySequence_Contains}{PyObject *o, PyObject *value}
Determine if \var{o} contains \var{value}. If an item in \var{o} is
equal to \var{value}, return \code{1}, otherwise return \code{0}.
On error, return \code{-1}. This is equivalent to the Python
expression \samp{\var{value} in \var{o}}.
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PySequence_Index}{PyObject *o, PyObject *value}
Return the first index \var{i} for which \code{\var{o}[\var{i}] ==
\var{value}}. On error, return \code{-1}. This is equivalent to
the Python expression \samp{\var{o}.index(\var{value})}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_List}{PyObject *o}
Return a list object with the same contents as the arbitrary
sequence \var{o}. The returned list is guaranteed to be new.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_Tuple}{PyObject *o}
Return a tuple object with the same contents as the arbitrary
sequence \var{o} or \NULL{} on failure. If \var{o} is a tuple,
a new reference will be returned, otherwise a tuple will be
constructed with the appropriate contents. This is equivalent
to the Python expression \samp{tuple(\var{o})}.
\bifuncindex{tuple}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_Fast}{PyObject *o, const char *m}
Returns the sequence \var{o} as a tuple, unless it is already a
tuple or list, in which case \var{o} is returned. Use
\cfunction{PySequence_Fast_GET_ITEM()} to access the members of the
result. Returns \NULL{} on failure. If the object is not a
sequence, raises \exception{TypeError} with \var{m} as the message
text.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_Fast_GET_ITEM}{PyObject *o, Py_ssize_t i}
Return the \var{i}th element of \var{o}, assuming that \var{o} was
returned by \cfunction{PySequence_Fast()}, \var{o} is not \NULL,
and that \var{i} is within bounds.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject**}{PySequence_Fast_ITEMS}{PyObject *o}
Return the underlying array of PyObject pointers. Assumes that
\var{o} was returned by \cfunction{PySequence_Fast()} and
\var{o} is not \NULL.
\versionadded{2.4}
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PySequence_ITEM}{PyObject *o, Py_ssize_t i}
Return the \var{i}th element of \var{o} or \NULL{} on failure.
Macro form of \cfunction{PySequence_GetItem()} but without checking
that \cfunction{PySequence_Check(\var{o})} is true and without
adjustment for negative indices.
\versionadded{2.3}
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PySequence_Fast_GET_SIZE}{PyObject *o}
Returns the length of \var{o}, assuming that \var{o} was
returned by \cfunction{PySequence_Fast()} and that \var{o} is
not \NULL. The size can also be gotten by calling
\cfunction{PySequence_Size()} on \var{o}, but
\cfunction{PySequence_Fast_GET_SIZE()} is faster because it can
assume \var{o} is a list or tuple.
\end{cfuncdesc}
\section{Mapping Protocol \label{mapping}}
\begin{cfuncdesc}{int}{PyMapping_Check}{PyObject *o}
Return \code{1} if the object provides mapping protocol, and
\code{0} otherwise. This function always succeeds.
\end{cfuncdesc}
\begin{cfuncdesc}{Py_ssize_t}{PyMapping_Length}{PyObject *o}
Returns the number of keys in object \var{o} on success, and
\code{-1} on failure. For objects that do not provide mapping
protocol, this is equivalent to the Python expression
\samp{len(\var{o})}.\bifuncindex{len}
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyMapping_DelItemString}{PyObject *o, char *key}
Remove the mapping for object \var{key} from the object \var{o}.
Return \code{-1} on failure. This is equivalent to the Python
statement \samp{del \var{o}[\var{key}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyMapping_DelItem}{PyObject *o, PyObject *key}
Remove the mapping for object \var{key} from the object \var{o}.
Return \code{-1} on failure. This is equivalent to the Python
statement \samp{del \var{o}[\var{key}]}.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyMapping_HasKeyString}{PyObject *o, char *key}
On success, return \code{1} if the mapping object has the key
\var{key} and \code{0} otherwise. This is equivalent to the Python
expression \samp{\var{o}.has_key(\var{key})}. This function always
succeeds.
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyMapping_HasKey}{PyObject *o, PyObject *key}
Return \code{1} if the mapping object has the key \var{key} and
\code{0} otherwise. This is equivalent to the Python expression
\samp{\var{o}.has_key(\var{key})}. This function always succeeds.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyMapping_Keys}{PyObject *o}
On success, return a list of the keys in object \var{o}. On
failure, return \NULL. This is equivalent to the Python expression
\samp{\var{o}.keys()}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyMapping_Values}{PyObject *o}
On success, return a list of the values in object \var{o}. On
failure, return \NULL. This is equivalent to the Python expression
\samp{\var{o}.values()}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyMapping_Items}{PyObject *o}
On success, return a list of the items in object \var{o}, where each
item is a tuple containing a key-value pair. On failure, return
\NULL. This is equivalent to the Python expression
\samp{\var{o}.items()}.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyMapping_GetItemString}{PyObject *o, char *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}{PyMapping_SetItemString}{PyObject *o, char *key,
PyObject *v}
Map the object \var{key} to the value \var{v} in object \var{o}.
Returns \code{-1} on failure. This is the equivalent of the Python
statement \samp{\var{o}[\var{key}] = \var{v}}.
\end{cfuncdesc}
\section{Iterator Protocol \label{iterator}}
\versionadded{2.2}
There are only a couple of functions specifically for working with
iterators.
\begin{cfuncdesc}{int}{PyIter_Check}{PyObject *o}
Return true if the object \var{o} supports the iterator protocol.
\end{cfuncdesc}
\begin{cfuncdesc}{PyObject*}{PyIter_Next}{PyObject *o}
Return the next value from the iteration \var{o}. If the object is
an iterator, this retrieves the next value from the iteration, and
returns \NULL{} with no exception set if there are no remaining
items. If the object is not an iterator, \exception{TypeError} is
raised, or if there is an error in retrieving the item, returns
\NULL{} and passes along the exception.
\end{cfuncdesc}
To write a loop which iterates over an iterator, the C code should
look something like this:
\begin{verbatim}
PyObject *iterator = PyObject_GetIter(obj);
PyObject *item;
if (iterator == NULL) {
/* propagate error */
}
while (item = PyIter_Next(iterator)) {
/* do something with item */
...
/* release reference when done */
Py_DECREF(item);
}
Py_DECREF(iterator);
if (PyErr_Occurred()) {
/* propagate error */
}
else {
/* continue doing useful work */
}
\end{verbatim}
\section{Buffer Protocol \label{abstract-buffer}}
\begin{cfuncdesc}{int}{PyObject_AsCharBuffer}{PyObject *obj,
const char **buffer,
Py_ssize_t *buffer_len}
Returns a pointer to a read-only memory location useable as character-
based input. The \var{obj} argument must support the single-segment
character buffer interface. On success, returns \code{0}, sets
\var{buffer} to the memory location and \var{buffer_len} to the buffer
length. Returns \code{-1} and sets a \exception{TypeError} on error.
\versionadded{1.6}
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyObject_AsReadBuffer}{PyObject *obj,
const void **buffer,
Py_ssize_t *buffer_len}
Returns a pointer to a read-only memory location containing
arbitrary data. The \var{obj} argument must support the
single-segment readable buffer interface. On success, returns
\code{0}, sets \var{buffer} to the memory location and \var{buffer_len}
to the buffer length. Returns \code{-1} and sets a
\exception{TypeError} on error.
\versionadded{1.6}
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyObject_CheckReadBuffer}{PyObject *o}
Returns \code{1} if \var{o} supports the single-segment readable
buffer interface. Otherwise returns \code{0}.
\versionadded{2.2}
\end{cfuncdesc}
\begin{cfuncdesc}{int}{PyObject_AsWriteBuffer}{PyObject *obj,
void **buffer,
Py_ssize_t *buffer_len}
Returns a pointer to a writeable memory location. The \var{obj}
argument must support the single-segment, character buffer
interface. On success, returns \code{0}, sets \var{buffer} to the
memory location and \var{buffer_len} to the buffer length. Returns
\code{-1} and sets a \exception{TypeError} on error.
\versionadded{1.6}
\end{cfuncdesc}