cpython/Doc/api.tex

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\title{Python-C API Reference}

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\begin{document}

\pagenumbering{roman}

\maketitle

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\begin{abstract}

\noindent
This manual documents the API used by C (or C++) programmers who want
to write extension modules or embed Python.  It is a companion to
``Extending and Embedding the Python Interpreter'', which describes
the general principles of extension writing but does not document the
API functions in detail.

\end{abstract}

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\tableofcontents
}

\pagebreak

\pagenumbering{arabic}


\chapter{Introduction}

From the viewpoint of of C access to Python services, we have:

\begin{enumerate}

\item "Very high level layer": two or three functions that let you
exec or eval arbitrary Python code given as a string in a module whose
name is given, passing C values in and getting C values out using
mkvalue/getargs style format strings.  This does not require the user
to declare any variables of type \code{PyObject *}.  This should be
enough to write a simple application that gets Python code from the
user, execs it, and returns the output or errors.

\item "Abstract objects layer": which is the subject of this chapter.
It has many functions operating on objects, and lest you do many
things from C that you can also write in Python, without going through
the Python parser.

\item "Concrete objects layer": This is the public type-dependent
interface provided by the standard built-in types, such as floats,
strings, and lists.  This interface exists and is currently documented
by the collection of include files provides with the Python
distributions.

\begin{enumerate}

From the point of view of Python accessing services provided by C
modules:

\end{enumerate}

\item[4] "Python module interface": this interface consist of the basic
routines used to define modules and their members.  Most of the
current extensions-writing guide deals with this interface.

\item[5] "Built-in object interface": this is the interface that a new
built-in type must provide and the mechanisms and rules that a
developer of a new built-in type must use and follow.

\end{enumerate}

The Python C API provides four groups of operations on objects,
corresponding to the same operations in the Python language: object,
numeric, sequence, and mapping.  Each protocol consists of a
collection of related operations.  If an operation that is not
provided by a particular type is invoked, then the standard exception
\code{TypeError} is raised with a operation name as an argument.

In addition, for convenience this interface defines a set of
constructors for building objects of built-in types.  This is needed
so new objects can be returned from C functions that otherwise treat
objects generically.

\section{Reference Counting}

For most of the functions in the Python-C API, if a function retains a
reference to a Python object passed as an argument, then the function
will increase the reference count of the object.  It is unnecessary
for the caller to increase the reference count of an argument in
anticipation of the object's retention.

Usually, Python objects returned from functions should be treated as
new objects.  Functions that return objects assume that the caller
will retain a reference and the reference count of the object has
already been incremented to account for this fact.  A caller that does
not retain a reference to an object that is returned from a function
must decrement the reference count of the object (using
\code{Py_DECREF()}) to prevent memory leaks.

Exceptions to these rules will be noted with the individual functions.

\section{Include Files}

All function, type and macro definitions needed to use the Python-C
API are included in your code by the following line:

\code{\#include "Python.h"}

This implies inclusion of the following standard header files:
stdio.h, string.h, errno.h, and stdlib.h (if available).

All user visible names defined by Python.h (except those defined by
the included standard headers) have one of the prefixes \code{Py} or
\code{_Py}.  Names beginning with \code{_Py} are for internal use
only.


\chapter{Initialization and Shutdown of an Embedded Python Interpreter}

When embedding the Python interpreter in a C or C++ program, the
interpreter must be initialized.

\begin{cfuncdesc}{void}{PyInitialize}{}
This function initializes the interpreter.  It must be called before
any interaction with the interpreter takes place.  If it is called
more than once, the second and further calls have no effect.

The function performs the following tasks: create an environment in
which modules can be imported and Python code can be executed;
initialize the \code{__builtin__} module; initialize the \code{sys}
module; initialize \code{sys.path}; initialize signal handling; and
create the empty \code{__main__} module.

In the current system, there is no way to undo all these
initializations or to create additional interpreter environments.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{Py_AtExit}{void (*func) ()}
Register a cleanup function to be called when Python exits.  The
cleanup function will be called with no arguments and should return no
value.  At most 32 cleanup functions can be registered.  When the
registration is successful, \code{Py_AtExit} returns 0; on failure, it
returns -1.  Each cleanup function will be called t most once.  The
cleanup function registered last is called first.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_Exit}{int status}
Exit the current process.  This calls \code{Py_Cleanup()} (see next
item) and performs additional cleanup (under some circumstances it
will attempt to delete all modules), and then calls the standard C
library function \code{exit(status)}.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_Cleanup}{}
Perform some of the cleanup that \code{Py_Exit} performs, but don't
exit the process.  In particular, this invokes the user's
\code{sys.exitfunc} function (if defined at all), and it invokes the
cleanup functions registered with \code{Py_AtExit()}, in reverse order
of their registration.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_FatalError}{char *message}
Print a fatal error message and die.  No cleanup is performed.  This
function should only be invoked when a condition is detected that
would make it dangerous to continue using the Python interpreter;
e.g., when the object administration appears to be corrupted.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{PyImport_Init}{}
Initialize the module table.  For internal use only.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{PyImport_Cleanup}{}
Empty the module table.  For internal use only.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{PyBuiltin_Init}{}
Initialize the \code{__builtin__} module.  For internal use only.
\end{cfuncdesc}


\chapter{Reference Counting}

The functions in this chapter are used for managing reference counts
of Python objects.

\begin{cfuncdesc}{void}{Py_INCREF}{PyObject *o}
Increment the reference count for object \code{o}.  The object must
not be \NULL{}; if you aren't sure that it isn't \NULL{}, use
\code{Py_XINCREF()}.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_XINCREF}{PyObject *o}
Increment the reference count for object \code{o}.  The object may be
\NULL{}, in which case the function has no effect.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_DECREF}{PyObject *o}
Decrement the reference count for object \code{o}.  The object must
not be \NULL{}; if you aren't sure that it isn't \NULL{}, use
\code{Py_XDECREF()}.  If the reference count reaches zero, the object's
type's deallocation function (which must not be \NULL{}) is invoked.

\strong{Warning:} The deallocation function can cause arbitrary Python
code to be invoked (e.g. when a class instance with a \code{__del__()}
method is deallocated).  While exceptions in such code are not
propagated, the executed code has free access to all Python global
variables.  This means that any object that is reachable from a global
variable should be in a consistent state before \code{Py_DECREF()} is
invoked.  For example, code to delete an object from a list should
copy a reference to the deleted object in a temporary variable, update
the list data structure, and then call \code{Py_DECREF()} for the
temporary variable.
\end{cfuncdesc}

\begin{cfuncdesc}{void}{Py_XDECREF}{PyObject *o}
Decrement the reference count for object \code{o}.The object may be
\NULL{}, in which case the function has no effect; otherwise the
effect is the same as for \code{Py_DECREF()}, and the same warning
applies.
\end{cfuncdesc}


\chapter{Exception Handling}

The functions in this chapter will let you handle and raise Python
exceptions.

\begin{cfuncdesc}{void}{PyErr_Print}{}
\end{cfuncdesc}


\chapter{Utilities}

The functions in this chapter perform various utility tasks, such as
parsing function arguments and constructing Python values from C
values.

\begin{cfuncdesc}{int}{Py_FdIsInteractive}{FILE *fp, char *filename}
Return true (nonzero) if the standard I/O file \code{fp} with name
\code{filename} is deemed interactive.  This is the case for files for
which \code{isatty(fileno(fp))} is true.  If the global flag
\code{Py_InteractiveFlag} is true, this function also returns true if
the \code{name} pointer is \NULL{} or if the name is equal to one of
the strings \code{"<stdin>"} or \code{"???"}.
\end{cfuncdesc}

\begin{cfuncdesc}{long}{PyOS_GetLastModificationTime}{char *filename}
Return the time of last modification of the file \code{filename}.
The result is encoded in the same way as the timestamp returned by
the standard C library function \code{time()}.
\end{cfuncdesc}


\chapter{Debugging}

XXX Explain Py_DEBUG, Py_TRACE_REFS, Py_REF_DEBUG.


\chapter{The Very High Level Layer}

The functions in this chapter will let you execute Python source code
given in a file or a buffer, but they will not let you interact in a
more detailed way with the interpreter.


\chapter{Abstract Objects Layer}

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 flag a Python exception.

\section{Object Protocol}

\begin{cfuncdesc}{int}{PyObject_Print}{PyObject *o, FILE *fp, int flags}
Print an object \code{o}, on file \code{fp}.  Returns -1 on error
The flags argument is used to enable certain printing
options. The only option currently supported is \code{Py_Print_RAW}. 
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PyObject_HasAttrString}{PyObject *o, char *attr_name}
Returns 1 if o has the attribute attr_name, and 0 otherwise.
This is equivalent to the Python expression:
\code{hasattr(o,attr_name)}.
This function always succeeds.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyObject_GetAttrString}{PyObject *o, char *attr_name}
Retrieve an attributed named attr_name form object o.
Returns the attribute value on success, or \NULL{} on failure.
This is the equivalent of the Python expression: \code{o.attr_name}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_HasAttr}{PyObject *o, PyObject *attr_name}
Returns 1 if o has the attribute attr_name, and 0 otherwise.
This is equivalent to the Python expression:
\code{hasattr(o,attr_name)}. 
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_GetAttr}{PyObject *o, PyObject *attr_name}
Retrieve an attributed named attr_name form object o.
Returns the attribute value on success, or \NULL{} on failure.
This is the equivalent of the Python expression: o.attr_name.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_SetAttrString}{PyObject *o, char *attr_name, PyObject *v}
Set the value of the attribute named \code{attr_name}, for object \code{o},
to the value \code{v}. Returns -1 on failure.  This is
the equivalent of the Python statement: \code{o.attr_name=v}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_SetAttr}{PyObject *o, PyObject *attr_name, PyObject *v}
Set the value of the attribute named \code{attr_name}, for
object \code{o},
to the value \code{v}. Returns -1 on failure.  This is
the equivalent of the Python statement: \code{o.attr_name=v}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_DelAttrString}{PyObject *o, char *attr_name}
Delete attribute named \code{attr_name}, for object \code{o}. Returns -1 on
failure.  This is the equivalent of the Python
statement: \code{del o.attr_name}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_DelAttr}{PyObject *o, PyObject *attr_name}
Delete attribute named \code{attr_name}, for object \code{o}. Returns -1 on
failure.  This is the equivalent of the Python
statement: \code{del o.attr_name}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_Cmp}{PyObject *o1, PyObject *o2, int *result}
Compare the values of \code{o1} and \code{o2} using a routine provided by
\code{o1}, if one exists, otherwise with a routine provided by \code{o2}.
The result of the comparison is returned in \code{result}.  Returns
-1 on failure.  This is the equivalent of the Python
statement: \code{result=cmp(o1,o2)}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_Compare}{PyObject *o1, PyObject *o2}
Compare the values of \code{o1} and \code{o2} using a routine provided by
\code{o1}, if one exists, otherwise with a routine provided by \code{o2}.
Returns the result of the comparison on success.  On error,
the value returned is undefined. This is equivalent to the
Python expression: \code{cmp(o1,o2)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_Repr}{PyObject *o}
Compute the string representation of object, \code{o}.  Returns the
string representation on success, \NULL{} on failure.  This is
the equivalent of the Python expression: \code{repr(o)}.
Called by the \code{repr()} built-in function and by reverse quotes.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_Str}{PyObject *o}
Compute the string representation of object, \code{o}.  Returns the
string representation on success, \NULL{} on failure.  This is
the equivalent of the Python expression: \code{str(o)}.
Called by the \code{str()} built-in function and by the \code{print}
statement.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyCallable_Check}{PyObject *o}
Determine if the object \code{o}, is callable.  Return 1 if the
object is callable and 0 otherwise.
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_CallObject}{PyObject *callable_object, PyObject *args}
Call a callable Python object \code{callable_object}, with
arguments given by the tuple \code{args}.  If no arguments are
needed, then args may be \NULL{}.  Returns the result of the
call on success, or \NULL{} on failure.  This is the equivalent
of the Python expression: \code{apply(o, args)}.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyObject_CallFunction}{PyObject *callable_object, char *format, ...}
Call a callable Python object \code{callable_object}, with a
variable number of C arguments. The C arguments are described
using a mkvalue-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: \code{apply(o,args)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_CallMethod}{PyObject *o, char *m, char *format, ...}
Call the method named \code{m} of object \code{o} with a variable number of
C arguments.  The C arguments are described by a mkvalue
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: \code{o.method(args)}.
Note that Special method names, such as "\code{__add__}",
"\code{__getitem__}", and so on are not supported. The specific
abstract-object routines for these must be used.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_Hash}{PyObject *o}
Compute and return the hash value of an object \code{o}.  On
failure, return -1.  This is the equivalent of the Python
expression: \code{hash(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_IsTrue}{PyObject *o}
Returns 1 if the object \code{o} is considered to be true, and
0 otherwise. This is equivalent to the Python expression:
\code{not not o}.
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_Type}{PyObject *o}
On success, returns a type object corresponding to the object
type of object \code{o}. On failure, returns \NULL{}.  This is
equivalent to the Python expression: \code{type(o)}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PyObject_Length}{PyObject *o}
Return the length of object \code{o}.  If the object \code{o} provides
both sequence and mapping protocols, the sequence length is
returned. On error, -1 is returned.  This is the equivalent
to the Python expression: \code{len(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyObject_GetItem}{PyObject *o, PyObject *key}
Return element of \code{o} corresponding to the object \code{key} or \NULL{}
on failure. This is the equivalent of the Python expression:
\code{o[key]}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_SetItem}{PyObject *o, PyObject *key, PyObject *v}
Map the object \code{key} to the value \code{v}.
Returns -1 on failure.  This is the equivalent
of the Python statement: \code{o[key]=v}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyObject_DelItem}{PyObject *o, PyObject *key, PyObject *v}
Delete the mapping for \code{key} from \code{*o}.  Returns -1
on failure.
This is the equivalent of the Python statement: del o[key].
\end{cfuncdesc}


\section{Number Protocol}

\begin{cfuncdesc}{int}{PyNumber_Check}{PyObject *o}
Returns 1 if the object \code{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 \code{o1} and \code{o2}, or null on failure.
This is the equivalent of the Python expression: \code{o1+o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Subtract}{PyObject *o1, PyObject *o2}
Returns the result of subtracting \code{o2} from \code{o1}, or null on
failure.  This is the equivalent of the Python expression:
\code{o1-o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Multiply}{PyObject *o1, PyObject *o2}
Returns the result of multiplying \code{o1} and \code{o2}, or null on
failure.  This is the equivalent of the Python expression:
\code{o1*o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Divide}{PyObject *o1, PyObject *o2}
Returns the result of dividing \code{o1} by \code{o2}, or null on failure.
This is the equivalent of the Python expression: \code{o1/o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Remainder}{PyObject *o1, PyObject *o2}
Returns the remainder of dividing \code{o1} by \code{o2}, or null on
failure.  This is the equivalent of the Python expression:
\code{o1\%o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Divmod}{PyObject *o1, PyObject *o2}
See the built-in function divmod.  Returns \NULL{} on failure.
This is the equivalent of the Python expression:
\code{divmod(o1,o2)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Power}{PyObject *o1, PyObject *o2, PyObject *o3}
See the built-in function pow.  Returns \NULL{} on failure.
This is the equivalent of the Python expression:
\code{pow(o1,o2,o3)}, where \code{o3} is optional.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Negative}{PyObject *o}
Returns the negation of \code{o} on success, or null on failure.
This is the equivalent of the Python expression: \code{-o}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Positive}{PyObject *o}
Returns \code{o} on success, or \NULL{} on failure.
This is the equivalent of the Python expression: \code{+o}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Absolute}{PyObject *o}
Returns the absolute value of \code{o}, or null on failure.  This is
the equivalent of the Python expression: \code{abs(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Invert}{PyObject *o}
Returns the bitwise negation of \code{o} on success, or \NULL{} on
failure.  This is the equivalent of the Python expression:
\code{~o}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Lshift}{PyObject *o1, PyObject *o2}
Returns the result of left shifting \code{o1} by \code{o2} on success, or
\NULL{} on failure.  This is the equivalent of the Python
expression: \code{o1 << o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Rshift}{PyObject *o1, PyObject *o2}
Returns the result of right shifting \code{o1} by \code{o2} on success, or
\NULL{} on failure.  This is the equivalent of the Python
expression: \code{o1 >> o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_And}{PyObject *o1, PyObject *o2}
Returns the result of "anding" \code{o2} and \code{o2} on success and \NULL{}
on failure. This is the equivalent of the Python
expression: \code{o1 and o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Xor}{PyObject *o1, PyObject *o2}
Returns the bitwise exclusive or of \code{o1} by \code{o2} on success, or
\NULL{} on failure.  This is the equivalent of the Python
expression: \code{o1\^{ }o2}.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyNumber_Or}{PyObject *o1, PyObject *o2}
Returns the result or \code{o1} and \code{o2} on success, or \NULL{} on
failure.  This is the equivalent of the Python expression: 
\code{o1 or o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Coerce}{PyObject *o1, PyObject *o2}
This function takes the addresses of two variables of type
\code{PyObject*}.

If the objects pointed to by \code{*p1} and \code{*p2} have the same type,
increment their reference count and return 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 0.
If no conversion is possible, or if some other error occurs,
return -1 (failure) and don't increment the reference counts.
The call \code{PyNumber_Coerce(\&o1, \&o2)} is equivalent to the Python
statement \code{o1, o2 = coerce(o1, o2)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Int}{PyObject *o}
Returns the \code{o} converted to an integer object on success, or
\NULL{} on failure.  This is the equivalent of the Python
expression: \code{int(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Long}{PyObject *o}
Returns the \code{o} converted to a long integer object on success,
or \NULL{} on failure.  This is the equivalent of the Python
expression: \code{long(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyNumber_Float}{PyObject *o}
Returns the \code{o} converted to a float object on success, or \NULL{}
on failure.  This is the equivalent of the Python expression:
\code{float(o)}.
\end{cfuncdesc}


\section{Sequence protocol}

\begin{cfuncdesc}{int}{PySequence_Check}{PyObject *o}
Return 1 if the object provides sequence protocol, and 0
otherwise.  
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PySequence_Concat}{PyObject *o1, PyObject *o2}
Return the concatination of \code{o1} and \code{o2} on success, and \NULL{} on
failure.   This is the equivalent of the Python
expression: \code{o1+o2}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PySequence_Repeat}{PyObject *o, int count}
Return the result of repeating sequence object \code{o} count times,
or \NULL{} on failure.  This is the equivalent of the Python
expression: \code{o*count}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PySequence_GetItem}{PyObject *o, int i}
Return the ith element of \code{o}, or \NULL{} on failure. This is the
equivalent of the Python expression: \code{o[i]}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PySequence_GetSlice}{PyObject *o, int i1, int i2}
Return the slice of sequence object \code{o} between \code{i1} and \code{i2}, or
\NULL{} on failure. This is the equivalent of the Python
expression, \code{o[i1:i2]}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PySequence_SetItem}{PyObject *o, int i, PyObject *v}
Assign object \code{v} to the \code{i}th element of \code{o}.
Returns -1 on failure.  This is the equivalent of the Python
statement, \code{o[i]=v}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_DelItem}{PyObject *o, int i}
Delete the \code{i}th element of object \code{v}.  Returns
-1 on failure.  This is the equivalent of the Python
statement: \code{del o[i]}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_SetSlice}{PyObject *o, int i1, int i2, PyObject *v}
Assign the sequence object \code{v} to the slice in sequence
object \code{o} from \code{i1} to \code{i2}.  This is the equivalent of the Python
statement, \code{o[i1:i2]=v}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_DelSlice}{PyObject *o, int i1, int i2}
Delete the slice in sequence object, \code{o}, from \code{i1} to \code{i2}.
Returns -1 on failure. This is the equivalent of the Python
statement: \code{del o[i1:i2]}.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PySequence_Tuple}{PyObject *o}
Returns the \code{o} as a tuple on success, and \NULL{} on failure.
This is equivalent to the Python expression: \code{tuple(o)}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_Count}{PyObject *o, PyObject *value}
Return the number of occurrences of \code{value} on \code{o}, that is,
return the number of keys for which \code{o[key]==value}.  On
failure, return -1.  This is equivalent to the Python
expression: \code{o.count(value)}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_In}{PyObject *o, PyObject *value}
Determine if \code{o} contains \code{value}.  If an item in \code{o} is equal to
\code{value}, return 1, otherwise return 0.  On error, return -1.  This
is equivalent to the Python expression: \code{value in o}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PySequence_Index}{PyObject *o, PyObject *value}
Return the first index for which \code{o[i]=value}.  On error,
return -1.    This is equivalent to the Python
expression: \code{o.index(value)}.
\end{cfuncdesc}

\section{Mapping protocol}

\begin{cfuncdesc}{int}{PyMapping_Check}{PyObject *o}
Return 1 if the object provides mapping protocol, and 0
otherwise.  
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyMapping_Length}{PyObject *o}
Returns the number of keys in object \code{o} on success, and -1 on
failure.  For objects that do not provide sequence protocol,
this is equivalent to the Python expression: \code{len(o)}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyMapping_DelItemString}{PyObject *o, char *key}
Remove the mapping for object \code{key} from the object \code{o}.
Return -1 on failure.  This is equivalent to
the Python statement: \code{del o[key]}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyMapping_DelItem}{PyObject *o, PyObject *key}
Remove the mapping for object \code{key} from the object \code{o}.
Return -1 on failure.  This is equivalent to
the Python statement: \code{del o[key]}.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyMapping_HasKeyString}{PyObject *o, char *key}
On success, return 1 if the mapping object has the key \code{key}
and 0 otherwise.  This is equivalent to the Python expression:
\code{o.has_key(key)}. 
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{int}{PyMapping_HasKey}{PyObject *o, PyObject *key}
Return 1 if the mapping object has the key \code{key}
and 0 otherwise.  This is equivalent to the Python expression:
\code{o.has_key(key)}. 
This function always succeeds.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyMapping_Keys}{PyObject *o}
On success, return a list of the keys in object \code{o}.  On
failure, return \NULL{}. This is equivalent to the Python
expression: \code{o.keys()}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyMapping_Values}{PyObject *o}
On success, return a list of the values in object \code{o}.  On
failure, return \NULL{}. This is equivalent to the Python
expression: \code{o.values()}.
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyMapping_Items}{PyObject *o}
On success, return a list of the items in object \code{o}, where
each item is a tuple containing a key-value pair.  On
failure, return \NULL{}. This is equivalent to the Python
expression: \code{o.items()}.
\end{cfuncdesc}

\begin{cfuncdesc}{int}{PyMapping_Clear}{PyObject *o}
Make object \code{o} empty.  Returns 1 on success and 0 on failure.
This is equivalent to the Python statement:
\code{for key in o.keys(): del o[key]}
\end{cfuncdesc}


\begin{cfuncdesc}{PyObject*}{PyMapping_GetItemString}{PyObject *o, char *key}
Return element of \code{o} corresponding to the object \code{key} or \NULL{}
on failure. This is the equivalent of the Python expression:
\code{o[key]}.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyMapping_SetItemString}{PyObject *o, char *key, PyObject *v}
Map the object \code{key} to the value \code{v} in object \code{o}.  Returns 
-1 on failure.  This is the equivalent of the Python
statement: \code{o[key]=v}.
\end{cfuncdesc}


\section{Constructors}

\begin{cfuncdesc}{PyObject*}{PyFile_FromString}{char *file_name, char *mode}
On success, returns a new file object that is opened on the
file given by \code{file_name}, with a file mode given by \code{mode},
where \code{mode} has the same semantics as the standard C routine,
fopen.  On failure, return -1.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyFile_FromFile}{FILE *fp, char *file_name, char *mode, int close_on_del}
Return a new file object for an already opened standard C
file pointer, \code{fp}.  A file name, \code{file_name}, and open mode,
\code{mode}, must be provided as well as a flag, \code{close_on_del}, that
indicates whether the file is to be closed when the file
object is destroyed.  On failure, return -1.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyFloat_FromDouble}{double v}
Returns a new float object with the value \code{v} on success, and
\NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyInt_FromLong}{long v}
Returns a new int object with the value \code{v} on success, and
\NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyList_New}{int l}
Returns a new list of length \code{l} on success, and \NULL{} on
failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyLong_FromLong}{long v}
Returns a new long object with the value \code{v} on success, and
\NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyLong_FromDouble}{double v}
Returns a new long object with the value \code{v} on success, and
\NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyDict_New}{}
Returns a new empty dictionary on success, and \NULL{} on
failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyString_FromString}{char *v}
Returns a new string object with the value \code{v} on success, and
\NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyString_FromStringAndSize}{char *v, int l}
Returns a new string object with the value \code{v} and length \code{l}
on success, and \NULL{} on failure.
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject*}{PyTuple_New}{int l}
Returns a new tuple of length \code{l} on success, and \NULL{} on
failure.
\end{cfuncdesc}


\chapter{Concrete Objects Layer}

The functions in this chapter are specific to certain Python object
types.  Passing them an object of the wrong type is not a good idea;
if you receive an object from a Python program and you are not sure
that it has the right type, you must perform a type check first;
e.g. to check that an object is a dictionary, use
\code{PyDict_Check()}.


\chapter{Defining New Object Types}

\begin{cfuncdesc}{PyObject *}{_PyObject_New}{PyTypeObject *type}
\end{cfuncdesc}

\begin{cfuncdesc}{PyObject *}{_PyObject_New}{PyTypeObject *type}
\end{cfuncdesc}

\input{api.ind}			% Index -- must be last

\end{document}