Commits

Christian Heimes committed fa6cee1

Merged revisions 60094-60123 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

*** NOTE ***
I haven't merged the files in Doc/c-api/. I got too many conflicts. Georg,
please split them manually.

........
r60095 | andrew.kuchling | 2008-01-19 21:12:04 +0100 (Sat, 19 Jan 2008) | 2 lines

Bug 1277: make Maildir use the user-provided factory instead of hard-wiring MaildirMessage.
2.5.2 bugfix candidate.
........
r60097 | georg.brandl | 2008-01-19 21:22:13 +0100 (Sat, 19 Jan 2008) | 4 lines

#1663329: add os.closerange() to close a range of fds,
ignoring errors, and use this in subprocess to speed up
subprocess creation in close_fds mode. Patch by Mike Klaas.
........
r60099 | georg.brandl | 2008-01-19 21:40:24 +0100 (Sat, 19 Jan 2008) | 2 lines

#1411695: clarify behavior of xml.sax.utils.[un]escape.
........
r60101 | andrew.kuchling | 2008-01-19 21:47:59 +0100 (Sat, 19 Jan 2008) | 7 lines

Patch #1019808 from Federico Schwindt: Return correct socket error when
a default timeout has been set, by using getsockopt() to get the error
condition (instead of trying another connect() call, which seems to be
a Linuxism).

2.5 bugfix candidate, assuming no one reports any problems with this change.
........
r60102 | gregory.p.smith | 2008-01-19 21:49:02 +0100 (Sat, 19 Jan 2008) | 3 lines

fix comment typos, use not arg instead of arg == "", add test coverage
for inside of the final if needquotes: within subprocess.list2cmdline().
........
r60103 | georg.brandl | 2008-01-19 21:53:07 +0100 (Sat, 19 Jan 2008) | 2 lines

#1509: fix sqlite3 docstrings and docs w.r.t. cursor.fetchXXX methods.
........
r60104 | gregory.p.smith | 2008-01-19 21:57:59 +0100 (Sat, 19 Jan 2008) | 6 lines

Fixes issue1336 - a race condition could occur when forking if the gc
kicked in during the critical section. solution: disable gc during
that section. Patch contributed by jpa and updated by me to cover the
race condition still existing what therve from twistedmatrix pointed
out (already seen and fixed in twisted's own subprocess code).
........
r60105 | gregory.p.smith | 2008-01-19 22:00:37 +0100 (Sat, 19 Jan 2008) | 2 lines

note about r60104
........
r60106 | andrew.kuchling | 2008-01-19 22:00:38 +0100 (Sat, 19 Jan 2008) | 1 line

Bug 1296: restore text describing OptionGroup
........
r60109 | georg.brandl | 2008-01-19 23:08:21 +0100 (Sat, 19 Jan 2008) | 2 lines

Split the monstrous C API manual files in smaller parts.
........
r60110 | georg.brandl | 2008-01-19 23:14:27 +0100 (Sat, 19 Jan 2008) | 2 lines

Missed one big file to split up.
........
r60111 | gregory.p.smith | 2008-01-19 23:23:56 +0100 (Sat, 19 Jan 2008) | 12 lines

Undo an unnecessary else: and indentation that r60104 added.

try:
...
except:
...
raise
else:
...

the else: is unecessary due to the blind except: with a raise.
........
r60115 | gregory.p.smith | 2008-01-19 23:49:37 +0100 (Sat, 19 Jan 2008) | 3 lines

Fix issue 1300: Quote command line arguments that contain a '|' character in
subprocess.list2cmdline (windows).
........
r60116 | gregory.p.smith | 2008-01-20 00:10:52 +0100 (Sun, 20 Jan 2008) | 3 lines

Fixes/Accepts Patch for issue1189216 - Work properly with archives
that have file headers past the 2**31 byte boundary.
........
r60119 | andrew.kuchling | 2008-01-20 01:00:38 +0100 (Sun, 20 Jan 2008) | 3 lines

Patch #1048820 from Stefan Wehr: add insert-mode editing to Textbox.
Fix an off-by-one error I noticed.
........
r60120 | andrew.kuchling | 2008-01-20 01:12:19 +0100 (Sun, 20 Jan 2008) | 1 line

Add an interactive test script for exercising curses
........
r60121 | gregory.p.smith | 2008-01-20 02:21:03 +0100 (Sun, 20 Jan 2008) | 7 lines

Fix zipfile decryption. The check for validity only worked on one
type of encrypted zip files. Files using extended local headers
needed to compare the check byte against different values. (according
to reading the infozip unzip crypt.c source code)

Fixes issue1003.
........
r60122 | gregory.p.smith | 2008-01-20 02:26:04 +0100 (Sun, 20 Jan 2008) | 2 lines

note for r60121
........
r60123 | gregory.p.smith | 2008-01-20 02:32:00 +0100 (Sun, 20 Jan 2008) | 4 lines

Document that zipfile decryption is insanely slow and fix a typo and
blatant lie in a docstring (it is not useful for security regardless of
how you spell it).
........

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File Doc/c-api/newtypes.rst

-.. highlightlang:: c
-
-
-.. _newtypes:
-
-*****************************
-Object Implementation Support
-*****************************
-
-This chapter describes the functions, types, and macros used when defining new
-object types.
-
-
-.. _allocating-objects:
-
-Allocating Objects on the Heap
-==============================
-
-
-.. cfunction:: PyObject* _PyObject_New(PyTypeObject *type)
-
-
-.. cfunction:: PyVarObject* _PyObject_NewVar(PyTypeObject *type, Py_ssize_t size)
-
-
-.. cfunction:: PyObject* PyObject_Init(PyObject *op, PyTypeObject *type)
-
-   Initialize a newly-allocated object *op* with its type and initial reference.
-   Returns the initialized object.  If *type* indicates that the object
-   participates in the cyclic garbage detector, it is added to the detector's set
-   of observed objects. Other fields of the object are not affected.
-
-
-.. cfunction:: PyVarObject* PyObject_InitVar(PyVarObject *op, PyTypeObject *type, Py_ssize_t size)
-
-   This does everything :cfunc:`PyObject_Init` does, and also initializes the
-   length information for a variable-size object.
-
-
-.. cfunction:: TYPE* PyObject_New(TYPE, PyTypeObject *type)
-
-   Allocate a new Python object using the C structure type *TYPE* and the Python
-   type object *type*.  Fields not defined by the Python object header are not
-   initialized; the object's reference count will be one.  The size of the memory
-   allocation is determined from the :attr:`tp_basicsize` field of the type object.
-
-
-.. cfunction:: TYPE* PyObject_NewVar(TYPE, PyTypeObject *type, Py_ssize_t size)
-
-   Allocate a new Python object using the C structure type *TYPE* and the Python
-   type object *type*.  Fields not defined by the Python object header are not
-   initialized.  The allocated memory allows for the *TYPE* structure plus *size*
-   fields of the size given by the :attr:`tp_itemsize` field of *type*.  This is
-   useful for implementing objects like tuples, which are able to determine their
-   size at construction time.  Embedding the array of fields into the same
-   allocation decreases the number of allocations, improving the memory management
-   efficiency.
-
-
-.. cfunction:: void PyObject_Del(PyObject *op)
-
-   Releases memory allocated to an object using :cfunc:`PyObject_New` or
-   :cfunc:`PyObject_NewVar`.  This is normally called from the :attr:`tp_dealloc`
-   handler specified in the object's type.  The fields of the object should not be
-   accessed after this call as the memory is no longer a valid Python object.
-
-
-.. cfunction:: PyObject* Py_InitModule(char *name, PyMethodDef *methods)
-
-   Create a new module object based on a name and table of functions, returning
-   the new module object; the *methods* argument can be *NULL* if no methods are
-   to be defined for the module.
-
-
-.. cfunction:: PyObject* Py_InitModule3(char *name, PyMethodDef *methods, char *doc)
-
-   Create a new module object based on a name and table of functions, returning
-   the new module object.  The *methods* argument can be *NULL* if no methods
-   are to be defined for the module.  If *doc* is non-*NULL*, it will be used to
-   define the docstring for the module.
-
-
-.. cfunction:: PyObject* Py_InitModule4(char *name, PyMethodDef *methods, char *doc, PyObject *self, int apiver)
-
-   Create a new module object based on a name and table of functions, returning
-   the new module object.  The *methods* argument can be *NULL* if no methods
-   are to be defined for the module.  If *doc* is non-*NULL*, it will be used to
-   define the docstring for the module.  If *self* is non-*NULL*, it will passed
-   to the functions of the module as their (otherwise *NULL*) first parameter.
-   (This was added as an experimental feature, and there are no known uses in
-   the current version of Python.)  For *apiver*, the only value which should be
-   passed is defined by the constant :const:`PYTHON_API_VERSION`.
-
-   .. note::
-
-      Most uses of this function should probably be using the :cfunc:`Py_InitModule3`
-      instead; only use this if you are sure you need it.
-
-
-.. cvar:: PyObject _Py_NoneStruct
-
-   Object which is visible in Python as ``None``.  This should only be accessed
-   using the :cmacro:`Py_None` macro, which evaluates to a pointer to this
-   object.
-
-
-.. _common-structs:
-
-Common Object Structures
-========================
-
-There are a large number of structures which are used in the definition of
-object types for Python.  This section describes these structures and how they
-are used.
-
-All Python objects ultimately share a small number of fields at the beginning of
-the object's representation in memory.  These are represented by the
-:ctype:`PyObject` and :ctype:`PyVarObject` types, which are defined, in turn, by
-the expansions of some macros also used, whether directly or indirectly, in the
-definition of all other Python objects.
-
-
-.. ctype:: PyObject
-
-   All object types are extensions of this type.  This is a type which contains the
-   information Python needs to treat a pointer to an object as an object.  In a
-   normal "release" build, it contains only the objects reference count and a
-   pointer to the corresponding type object.  It corresponds to the fields defined
-   by the expansion of the ``PyObject_HEAD`` macro.
-
-
-.. ctype:: PyVarObject
-
-   This is an extension of :ctype:`PyObject` that adds the :attr:`ob_size` field.
-   This is only used for objects that have some notion of *length*.  This type does
-   not often appear in the Python/C API.  It corresponds to the fields defined by
-   the expansion of the ``PyObject_VAR_HEAD`` macro.
-
-These macros are used in the definition of :ctype:`PyObject` and
-:ctype:`PyVarObject`:
-
-.. XXX need to document PEP 3123 changes here
-
-.. cmacro:: PyObject_HEAD
-
-   This is a macro which expands to the declarations of the fields of the
-   :ctype:`PyObject` type; it is used when declaring new types which represent
-   objects without a varying length.  The specific fields it expands to depend on
-   the definition of :cmacro:`Py_TRACE_REFS`.  By default, that macro is not
-   defined, and :cmacro:`PyObject_HEAD` expands to::
-
-      Py_ssize_t ob_refcnt;
-      PyTypeObject *ob_type;
-
-   When :cmacro:`Py_TRACE_REFS` is defined, it expands to::
-
-      PyObject *_ob_next, *_ob_prev;
-      Py_ssize_t ob_refcnt;
-      PyTypeObject *ob_type;
-
-
-.. cmacro:: PyObject_VAR_HEAD
-
-   This is a macro which expands to the declarations of the fields of the
-   :ctype:`PyVarObject` type; it is used when declaring new types which represent
-   objects with a length that varies from instance to instance.  This macro always
-   expands to::
-
-      PyObject_HEAD
-      Py_ssize_t ob_size;
-
-   Note that :cmacro:`PyObject_HEAD` is part of the expansion, and that its own
-   expansion varies depending on the definition of :cmacro:`Py_TRACE_REFS`.
-
-.. cmacro:: PyObject_HEAD_INIT
-
-
-.. ctype:: PyCFunction
-
-   Type of the functions used to implement most Python callables in C. Functions of
-   this type take two :ctype:`PyObject\*` parameters and return one such value.  If
-   the return value is *NULL*, an exception shall have been set.  If not *NULL*,
-   the return value is interpreted as the return value of the function as exposed
-   in Python.  The function must return a new reference.
-
-
-.. ctype:: PyCFunctionWithKeywords
-
-   Type of the functions used to implement Python callables in C that take
-   keyword arguments: they take three :ctype:`PyObject\*` parameters and return
-   one such value.  See :ctype:`PyCFunction` above for the meaning of the return
-   value.
-
-
-.. ctype:: PyMethodDef
-
-   Structure used to describe a method of an extension type.  This structure has
-   four fields:
-
-   +------------------+-------------+-------------------------------+
-   | Field            | C Type      | Meaning                       |
-   +==================+=============+===============================+
-   | :attr:`ml_name`  | char \*     | name of the method            |
-   +------------------+-------------+-------------------------------+
-   | :attr:`ml_meth`  | PyCFunction | pointer to the C              |
-   |                  |             | implementation                |
-   +------------------+-------------+-------------------------------+
-   | :attr:`ml_flags` | int         | flag bits indicating how the  |
-   |                  |             | call should be constructed    |
-   +------------------+-------------+-------------------------------+
-   | :attr:`ml_doc`   | char \*     | points to the contents of the |
-   |                  |             | docstring                     |
-   +------------------+-------------+-------------------------------+
-
-The :attr:`ml_meth` is a C function pointer.  The functions may be of different
-types, but they always return :ctype:`PyObject\*`.  If the function is not of
-the :ctype:`PyCFunction`, the compiler will require a cast in the method table.
-Even though :ctype:`PyCFunction` defines the first parameter as
-:ctype:`PyObject\*`, it is common that the method implementation uses a the
-specific C type of the *self* object.
-
-The :attr:`ml_flags` field is a bitfield which can include the following flags.
-The individual flags indicate either a calling convention or a binding
-convention.  Of the calling convention flags, only :const:`METH_VARARGS` and
-:const:`METH_KEYWORDS` can be combined (but note that :const:`METH_KEYWORDS`
-alone is equivalent to ``METH_VARARGS | METH_KEYWORDS``). Any of the calling
-convention flags can be combined with a binding flag.
-
-
-.. data:: METH_VARARGS
-
-   This is the typical calling convention, where the methods have the type
-   :ctype:`PyCFunction`. The function expects two :ctype:`PyObject\*` values.  The
-   first one is the *self* object for methods; for module functions, it has the
-   value given to :cfunc:`Py_InitModule4` (or *NULL* if :cfunc:`Py_InitModule` was
-   used).  The second parameter (often called *args*) is a tuple object
-   representing all arguments. This parameter is typically processed using
-   :cfunc:`PyArg_ParseTuple` or :cfunc:`PyArg_UnpackTuple`.
-
-
-.. data:: METH_KEYWORDS
-
-   Methods with these flags must be of type :ctype:`PyCFunctionWithKeywords`.  The
-   function expects three parameters: *self*, *args*, and a dictionary of all the
-   keyword arguments.  The flag is typically combined with :const:`METH_VARARGS`,
-   and the parameters are typically processed using
-   :cfunc:`PyArg_ParseTupleAndKeywords`.
-
-
-.. data:: METH_NOARGS
-
-   Methods without parameters don't need to check whether arguments are given if
-   they are listed with the :const:`METH_NOARGS` flag.  They need to be of type
-   :ctype:`PyCFunction`.  When used with object methods, the first parameter is
-   typically named ``self`` and will hold a reference to the object instance.  In
-   all cases the second parameter will be *NULL*.
-
-
-.. data:: METH_O
-
-   Methods with a single object argument can be listed with the :const:`METH_O`
-   flag, instead of invoking :cfunc:`PyArg_ParseTuple` with a ``"O"`` argument.
-   They have the type :ctype:`PyCFunction`, with the *self* parameter, and a
-   :ctype:`PyObject\*` parameter representing the single argument.
-
-
-These two constants are not used to indicate the calling convention but the
-binding when use with methods of classes.  These may not be used for functions
-defined for modules.  At most one of these flags may be set for any given
-method.
-
-
-.. data:: METH_CLASS
-
-   .. index:: builtin: classmethod
-
-   The method will be passed the type object as the first parameter rather than an
-   instance of the type.  This is used to create *class methods*, similar to what
-   is created when using the :func:`classmethod` built-in function.
-
-
-.. data:: METH_STATIC
-
-   .. index:: builtin: staticmethod
-
-   The method will be passed *NULL* as the first parameter rather than an instance
-   of the type.  This is used to create *static methods*, similar to what is
-   created when using the :func:`staticmethod` built-in function.
-
-One other constant controls whether a method is loaded in place of another
-definition with the same method name.
-
-
-.. data:: METH_COEXIST
-
-   The method will be loaded in place of existing definitions.  Without
-   *METH_COEXIST*, the default is to skip repeated definitions.  Since slot
-   wrappers are loaded before the method table, the existence of a *sq_contains*
-   slot, for example, would generate a wrapped method named :meth:`__contains__`
-   and preclude the loading of a corresponding PyCFunction with the same name.
-   With the flag defined, the PyCFunction will be loaded in place of the wrapper
-   object and will co-exist with the slot.  This is helpful because calls to
-   PyCFunctions are optimized more than wrapper object calls.
-
-
-.. cfunction:: PyObject* Py_FindMethod(PyMethodDef table[], PyObject *ob, char *name)
-
-   Return a bound method object for an extension type implemented in C.  This can
-   be useful in the implementation of a :attr:`tp_getattro` or :attr:`tp_getattr`
-   handler that does not use the :cfunc:`PyObject_GenericGetAttr` function.
-
-
-.. _type-structs:
-
-Type Objects
-============
-
-Perhaps one of the most important structures of the Python object system is the
-structure that defines a new type: the :ctype:`PyTypeObject` structure.  Type
-objects can be handled using any of the :cfunc:`PyObject_\*` or
-:cfunc:`PyType_\*` functions, but do not offer much that's interesting to most
-Python applications. These objects are fundamental to how objects behave, so
-they are very important to the interpreter itself and to any extension module
-that implements new types.
-
-Type objects are fairly large compared to most of the standard types. The reason
-for the size is that each type object stores a large number of values, mostly C
-function pointers, each of which implements a small part of the type's
-functionality.  The fields of the type object are examined in detail in this
-section.  The fields will be described in the order in which they occur in the
-structure.
-
-Typedefs: unaryfunc, binaryfunc, ternaryfunc, inquiry, intargfunc,
-intintargfunc, intobjargproc, intintobjargproc, objobjargproc, destructor,
-freefunc, printfunc, getattrfunc, getattrofunc, setattrfunc, setattrofunc,
-cmpfunc, reprfunc, hashfunc
-
-The structure definition for :ctype:`PyTypeObject` can be found in
-:file:`Include/object.h`.  For convenience of reference, this repeats the
-definition found there:
-
-.. literalinclude:: ../includes/typestruct.h
-
-
-The type object structure extends the :ctype:`PyVarObject` structure. The
-:attr:`ob_size` field is used for dynamic types (created by  :func:`type_new`,
-usually called from a class statement). Note that :cdata:`PyType_Type` (the
-metatype) initializes :attr:`tp_itemsize`, which means that its instances (i.e.
-type objects) *must* have the :attr:`ob_size` field.
-
-
-.. cmember:: PyObject* PyObject._ob_next
-             PyObject* PyObject._ob_prev
-
-   These fields are only present when the macro ``Py_TRACE_REFS`` is defined.
-   Their initialization to *NULL* is taken care of by the ``PyObject_HEAD_INIT``
-   macro.  For statically allocated objects, these fields always remain *NULL*.
-   For dynamically allocated objects, these two fields are used to link the object
-   into a doubly-linked list of *all* live objects on the heap.  This could be used
-   for various debugging purposes; currently the only use is to print the objects
-   that are still alive at the end of a run when the environment variable
-   :envvar:`PYTHONDUMPREFS` is set.
-
-   These fields are not inherited by subtypes.
-
-
-.. cmember:: Py_ssize_t PyObject.ob_refcnt
-
-   This is the type object's reference count, initialized to ``1`` by the
-   ``PyObject_HEAD_INIT`` macro.  Note that for statically allocated type objects,
-   the type's instances (objects whose :attr:`ob_type` points back to the type) do
-   *not* count as references.  But for dynamically allocated type objects, the
-   instances *do* count as references.
-
-   This field is not inherited by subtypes.
-
-
-.. cmember:: PyTypeObject* PyObject.ob_type
-
-   This is the type's type, in other words its metatype.  It is initialized by the
-   argument to the ``PyObject_HEAD_INIT`` macro, and its value should normally be
-   ``&PyType_Type``.  However, for dynamically loadable extension modules that must
-   be usable on Windows (at least), the compiler complains that this is not a valid
-   initializer.  Therefore, the convention is to pass *NULL* to the
-   ``PyObject_HEAD_INIT`` macro and to initialize this field explicitly at the
-   start of the module's initialization function, before doing anything else.  This
-   is typically done like this::
-
-      Foo_Type.ob_type = &PyType_Type;
-
-   This should be done before any instances of the type are created.
-   :cfunc:`PyType_Ready` checks if :attr:`ob_type` is *NULL*, and if so,
-   initializes it: in Python 2.2, it is set to ``&PyType_Type``; in Python 2.2.1
-   and later it is initialized to the :attr:`ob_type` field of the base class.
-   :cfunc:`PyType_Ready` will not change this field if it is non-zero.
-
-   In Python 2.2, this field is not inherited by subtypes.  In 2.2.1, and in 2.3
-   and beyond, it is inherited by subtypes.
-
-
-.. cmember:: Py_ssize_t PyVarObject.ob_size
-
-   For statically allocated type objects, this should be initialized to zero.  For
-   dynamically allocated type objects, this field has a special internal meaning.
-
-   This field is not inherited by subtypes.
-
-
-.. cmember:: char* PyTypeObject.tp_name
-
-   Pointer to a NUL-terminated string containing the name of the type. For types
-   that are accessible as module globals, the string should be the full module
-   name, followed by a dot, followed by the type name; for built-in types, it
-   should be just the type name.  If the module is a submodule of a package, the
-   full package name is part of the full module name.  For example, a type named
-   :class:`T` defined in module :mod:`M` in subpackage :mod:`Q` in package :mod:`P`
-   should have the :attr:`tp_name` initializer ``"P.Q.M.T"``.
-
-   For dynamically allocated type objects, this should just be the type name, and
-   the module name explicitly stored in the type dict as the value for key
-   ``'__module__'``.
-
-   For statically allocated type objects, the tp_name field should contain a dot.
-   Everything before the last dot is made accessible as the :attr:`__module__`
-   attribute, and everything after the last dot is made accessible as the
-   :attr:`__name__` attribute.
-
-   If no dot is present, the entire :attr:`tp_name` field is made accessible as the
-   :attr:`__name__` attribute, and the :attr:`__module__` attribute is undefined
-   (unless explicitly set in the dictionary, as explained above).  This means your
-   type will be impossible to pickle.
-
-   This field is not inherited by subtypes.
-
-
-.. cmember:: Py_ssize_t PyTypeObject.tp_basicsize
-             Py_ssize_t PyTypeObject.tp_itemsize
-
-   These fields allow calculating the size in bytes of instances of the type.
-
-   There are two kinds of types: types with fixed-length instances have a zero
-   :attr:`tp_itemsize` field, types with variable-length instances have a non-zero
-   :attr:`tp_itemsize` field.  For a type with fixed-length instances, all
-   instances have the same size, given in :attr:`tp_basicsize`.
-
-   For a type with variable-length instances, the instances must have an
-   :attr:`ob_size` field, and the instance size is :attr:`tp_basicsize` plus N
-   times :attr:`tp_itemsize`, where N is the "length" of the object.  The value of
-   N is typically stored in the instance's :attr:`ob_size` field.  There are
-   exceptions:  for example, long ints use a negative :attr:`ob_size` to indicate a
-   negative number, and N is ``abs(ob_size)`` there.  Also, the presence of an
-   :attr:`ob_size` field in the instance layout doesn't mean that the instance
-   structure is variable-length (for example, the structure for the list type has
-   fixed-length instances, yet those instances have a meaningful :attr:`ob_size`
-   field).
-
-   The basic size includes the fields in the instance declared by the macro
-   :cmacro:`PyObject_HEAD` or :cmacro:`PyObject_VAR_HEAD` (whichever is used to
-   declare the instance struct) and this in turn includes the :attr:`_ob_prev` and
-   :attr:`_ob_next` fields if they are present.  This means that the only correct
-   way to get an initializer for the :attr:`tp_basicsize` is to use the
-   ``sizeof`` operator on the struct used to declare the instance layout.
-   The basic size does not include the GC header size (this is new in Python 2.2;
-   in 2.1 and 2.0, the GC header size was included in :attr:`tp_basicsize`).
-
-   These fields are inherited separately by subtypes.  If the base type has a
-   non-zero :attr:`tp_itemsize`, it is generally not safe to set
-   :attr:`tp_itemsize` to a different non-zero value in a subtype (though this
-   depends on the implementation of the base type).
-
-   A note about alignment: if the variable items require a particular alignment,
-   this should be taken care of by the value of :attr:`tp_basicsize`.  Example:
-   suppose a type implements an array of ``double``. :attr:`tp_itemsize` is
-   ``sizeof(double)``. It is the programmer's responsibility that
-   :attr:`tp_basicsize` is a multiple of ``sizeof(double)`` (assuming this is the
-   alignment requirement for ``double``).
-
-
-.. cmember:: destructor PyTypeObject.tp_dealloc
-
-   A pointer to the instance destructor function.  This function must be defined
-   unless the type guarantees that its instances will never be deallocated (as is
-   the case for the singletons ``None`` and ``Ellipsis``).
-
-   The destructor function is called by the :cfunc:`Py_DECREF` and
-   :cfunc:`Py_XDECREF` macros when the new reference count is zero.  At this point,
-   the instance is still in existence, but there are no references to it.  The
-   destructor function should free all references which the instance owns, free all
-   memory buffers owned by the instance (using the freeing function corresponding
-   to the allocation function used to allocate the buffer), and finally (as its
-   last action) call the type's :attr:`tp_free` function.  If the type is not
-   subtypable (doesn't have the :const:`Py_TPFLAGS_BASETYPE` flag bit set), it is
-   permissible to call the object deallocator directly instead of via
-   :attr:`tp_free`.  The object deallocator should be the one used to allocate the
-   instance; this is normally :cfunc:`PyObject_Del` if the instance was allocated
-   using :cfunc:`PyObject_New` or :cfunc:`PyObject_VarNew`, or
-   :cfunc:`PyObject_GC_Del` if the instance was allocated using
-   :cfunc:`PyObject_GC_New` or :cfunc:`PyObject_GC_VarNew`.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: printfunc PyTypeObject.tp_print
-
-   An optional pointer to the instance print function.
-
-   The print function is only called when the instance is printed to a *real* file;
-   when it is printed to a pseudo-file (like a :class:`StringIO` instance), the
-   instance's :attr:`tp_repr` or :attr:`tp_str` function is called to convert it to
-   a string.  These are also called when the type's :attr:`tp_print` field is
-   *NULL*.  A type should never implement :attr:`tp_print` in a way that produces
-   different output than :attr:`tp_repr` or :attr:`tp_str` would.
-
-   The print function is called with the same signature as :cfunc:`PyObject_Print`:
-   ``int tp_print(PyObject *self, FILE *file, int flags)``.  The *self* argument is
-   the instance to be printed.  The *file* argument is the stdio file to which it
-   is to be printed.  The *flags* argument is composed of flag bits. The only flag
-   bit currently defined is :const:`Py_PRINT_RAW`. When the :const:`Py_PRINT_RAW`
-   flag bit is set, the instance should be printed the same way as :attr:`tp_str`
-   would format it; when the :const:`Py_PRINT_RAW` flag bit is clear, the instance
-   should be printed the same was as :attr:`tp_repr` would format it. It should
-   return ``-1`` and set an exception condition when an error occurred during the
-   comparison.
-
-   It is possible that the :attr:`tp_print` field will be deprecated. In any case,
-   it is recommended not to define :attr:`tp_print`, but instead to rely on
-   :attr:`tp_repr` and :attr:`tp_str` for printing.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: getattrfunc PyTypeObject.tp_getattr
-
-   An optional pointer to the get-attribute-string function.
-
-   This field is deprecated.  When it is defined, it should point to a function
-   that acts the same as the :attr:`tp_getattro` function, but taking a C string
-   instead of a Python string object to give the attribute name.  The signature is
-   the same as for :cfunc:`PyObject_GetAttrString`.
-
-   This field is inherited by subtypes together with :attr:`tp_getattro`: a subtype
-   inherits both :attr:`tp_getattr` and :attr:`tp_getattro` from its base type when
-   the subtype's :attr:`tp_getattr` and :attr:`tp_getattro` are both *NULL*.
-
-
-.. cmember:: setattrfunc PyTypeObject.tp_setattr
-
-   An optional pointer to the set-attribute-string function.
-
-   This field is deprecated.  When it is defined, it should point to a function
-   that acts the same as the :attr:`tp_setattro` function, but taking a C string
-   instead of a Python string object to give the attribute name.  The signature is
-   the same as for :cfunc:`PyObject_SetAttrString`.
-
-   This field is inherited by subtypes together with :attr:`tp_setattro`: a subtype
-   inherits both :attr:`tp_setattr` and :attr:`tp_setattro` from its base type when
-   the subtype's :attr:`tp_setattr` and :attr:`tp_setattro` are both *NULL*.
-
-
-.. cmember:: cmpfunc PyTypeObject.tp_compare
-
-   An optional pointer to the three-way comparison function.
-
-   The signature is the same as for :cfunc:`PyObject_Compare`. The function should
-   return ``1`` if *self* greater than *other*, ``0`` if *self* is equal to
-   *other*, and ``-1`` if *self* less than *other*.  It should return ``-1`` and
-   set an exception condition when an error occurred during the comparison.
-
-   This field is inherited by subtypes together with :attr:`tp_richcompare` and
-   :attr:`tp_hash`: a subtypes inherits all three of :attr:`tp_compare`,
-   :attr:`tp_richcompare`, and :attr:`tp_hash` when the subtype's
-   :attr:`tp_compare`, :attr:`tp_richcompare`, and :attr:`tp_hash` are all *NULL*.
-
-
-.. cmember:: reprfunc PyTypeObject.tp_repr
-
-   .. index:: builtin: repr
-
-   An optional pointer to a function that implements the built-in function
-   :func:`repr`.
-
-   The signature is the same as for :cfunc:`PyObject_Repr`; it must return a string
-   or a Unicode object.  Ideally, this function should return a string that, when
-   passed to :func:`eval`, given a suitable environment, returns an object with the
-   same value.  If this is not feasible, it should return a string starting with
-   ``'<'`` and ending with ``'>'`` from which both the type and the value of the
-   object can be deduced.
-
-   When this field is not set, a string of the form ``<%s object at %p>`` is
-   returned, where ``%s`` is replaced by the type name, and ``%p`` by the object's
-   memory address.
-
-   This field is inherited by subtypes.
-
-.. cmember:: PyNumberMethods* tp_as_number
-
-   Pointer to an additional structure that contains fields relevant only to
-   objects which implement the number protocol.  These fields are documented in
-   :ref:`number-structs`.
-
-   The :attr:`tp_as_number` field is not inherited, but the contained fields are
-   inherited individually.
-
-
-.. cmember:: PySequenceMethods* tp_as_sequence
-
-   Pointer to an additional structure that contains fields relevant only to
-   objects which implement the sequence protocol.  These fields are documented
-   in :ref:`sequence-structs`.
-
-   The :attr:`tp_as_sequence` field is not inherited, but the contained fields
-   are inherited individually.
-
-
-.. cmember:: PyMappingMethods* tp_as_mapping
-
-   Pointer to an additional structure that contains fields relevant only to
-   objects which implement the mapping protocol.  These fields are documented in
-   :ref:`mapping-structs`.
-
-   The :attr:`tp_as_mapping` field is not inherited, but the contained fields
-   are inherited individually.
-
-
-.. cmember:: hashfunc PyTypeObject.tp_hash
-
-   .. index:: builtin: hash
-
-   An optional pointer to a function that implements the built-in function
-   :func:`hash`.
-
-   The signature is the same as for :cfunc:`PyObject_Hash`; it must return a C
-   long.  The value ``-1`` should not be returned as a normal return value; when an
-   error occurs during the computation of the hash value, the function should set
-   an exception and return ``-1``.
-
-   When this field is not set, two possibilities exist: if the :attr:`tp_compare`
-   and :attr:`tp_richcompare` fields are both *NULL*, a default hash value based on
-   the object's address is returned; otherwise, a :exc:`TypeError` is raised.
-
-   This field is inherited by subtypes together with :attr:`tp_richcompare` and
-   :attr:`tp_compare`: a subtypes inherits all three of :attr:`tp_compare`,
-   :attr:`tp_richcompare`, and :attr:`tp_hash`, when the subtype's
-   :attr:`tp_compare`, :attr:`tp_richcompare` and :attr:`tp_hash` are all *NULL*.
-
-
-.. cmember:: ternaryfunc PyTypeObject.tp_call
-
-   An optional pointer to a function that implements calling the object.  This
-   should be *NULL* if the object is not callable.  The signature is the same as
-   for :cfunc:`PyObject_Call`.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: reprfunc PyTypeObject.tp_str
-
-   An optional pointer to a function that implements the built-in operation
-   :func:`str`.  (Note that :class:`str` is a type now, and :func:`str` calls the
-   constructor for that type.  This constructor calls :cfunc:`PyObject_Str` to do
-   the actual work, and :cfunc:`PyObject_Str` will call this handler.)
-
-   The signature is the same as for :cfunc:`PyObject_Str`; it must return a string
-   or a Unicode object.  This function should return a "friendly" string
-   representation of the object, as this is the representation that will be used,
-   among other things, by the :func:`print` function.
-
-   When this field is not set, :cfunc:`PyObject_Repr` is called to return a string
-   representation.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: getattrofunc PyTypeObject.tp_getattro
-
-   An optional pointer to the get-attribute function.
-
-   The signature is the same as for :cfunc:`PyObject_GetAttr`.  It is usually
-   convenient to set this field to :cfunc:`PyObject_GenericGetAttr`, which
-   implements the normal way of looking for object attributes.
-
-   This field is inherited by subtypes together with :attr:`tp_getattr`: a subtype
-   inherits both :attr:`tp_getattr` and :attr:`tp_getattro` from its base type when
-   the subtype's :attr:`tp_getattr` and :attr:`tp_getattro` are both *NULL*.
-
-
-.. cmember:: setattrofunc PyTypeObject.tp_setattro
-
-   An optional pointer to the set-attribute function.
-
-   The signature is the same as for :cfunc:`PyObject_SetAttr`.  It is usually
-   convenient to set this field to :cfunc:`PyObject_GenericSetAttr`, which
-   implements the normal way of setting object attributes.
-
-   This field is inherited by subtypes together with :attr:`tp_setattr`: a subtype
-   inherits both :attr:`tp_setattr` and :attr:`tp_setattro` from its base type when
-   the subtype's :attr:`tp_setattr` and :attr:`tp_setattro` are both *NULL*.
-
-
-.. cmember:: PyBufferProcs* PyTypeObject.tp_as_buffer
-
-   Pointer to an additional structure that contains fields relevant only to objects
-   which implement the buffer interface.  These fields are documented in
-   :ref:`buffer-structs`.
-
-   The :attr:`tp_as_buffer` field is not inherited, but the contained fields are
-   inherited individually.
-
-
-.. cmember:: long PyTypeObject.tp_flags
-
-   This field is a bit mask of various flags.  Some flags indicate variant
-   semantics for certain situations; others are used to indicate that certain
-   fields in the type object (or in the extension structures referenced via
-   :attr:`tp_as_number`, :attr:`tp_as_sequence`, :attr:`tp_as_mapping`, and
-   :attr:`tp_as_buffer`) that were historically not always present are valid; if
-   such a flag bit is clear, the type fields it guards must not be accessed and
-   must be considered to have a zero or *NULL* value instead.
-
-   Inheritance of this field is complicated.  Most flag bits are inherited
-   individually, i.e. if the base type has a flag bit set, the subtype inherits
-   this flag bit.  The flag bits that pertain to extension structures are strictly
-   inherited if the extension structure is inherited, i.e. the base type's value of
-   the flag bit is copied into the subtype together with a pointer to the extension
-   structure.  The :const:`Py_TPFLAGS_HAVE_GC` flag bit is inherited together with
-   the :attr:`tp_traverse` and :attr:`tp_clear` fields, i.e. if the
-   :const:`Py_TPFLAGS_HAVE_GC` flag bit is clear in the subtype and the
-   :attr:`tp_traverse` and :attr:`tp_clear` fields in the subtype exist (as
-   indicated by the :const:`Py_TPFLAGS_HAVE_RICHCOMPARE` flag bit) and have *NULL*
-   values.
-
-   The following bit masks are currently defined; these can be ORed together using
-   the ``|`` operator to form the value of the :attr:`tp_flags` field.  The macro
-   :cfunc:`PyType_HasFeature` takes a type and a flags value, *tp* and *f*, and
-   checks whether ``tp->tp_flags & f`` is non-zero.
-
-
-   .. data:: Py_TPFLAGS_HAVE_GETCHARBUFFER
-
-      If this bit is set, the :ctype:`PyBufferProcs` struct referenced by
-      :attr:`tp_as_buffer` has the :attr:`bf_getcharbuffer` field.
-
-
-   .. data:: Py_TPFLAGS_HAVE_SEQUENCE_IN
-
-      If this bit is set, the :ctype:`PySequenceMethods` struct referenced by
-      :attr:`tp_as_sequence` has the :attr:`sq_contains` field.
-
-
-   .. data:: Py_TPFLAGS_GC
-
-      This bit is obsolete.  The bit it used to name is no longer in use.  The symbol
-      is now defined as zero.
-
-
-   .. data:: Py_TPFLAGS_HAVE_INPLACEOPS
-
-      If this bit is set, the :ctype:`PySequenceMethods` struct referenced by
-      :attr:`tp_as_sequence` and the :ctype:`PyNumberMethods` structure referenced by
-      :attr:`tp_as_number` contain the fields for in-place operators. In particular,
-      this means that the :ctype:`PyNumberMethods` structure has the fields
-      :attr:`nb_inplace_add`, :attr:`nb_inplace_subtract`,
-      :attr:`nb_inplace_multiply`, :attr:`nb_inplace_divide`,
-      :attr:`nb_inplace_remainder`, :attr:`nb_inplace_power`,
-      :attr:`nb_inplace_lshift`, :attr:`nb_inplace_rshift`, :attr:`nb_inplace_and`,
-      :attr:`nb_inplace_xor`, and :attr:`nb_inplace_or`; and the
-      :ctype:`PySequenceMethods` struct has the fields :attr:`sq_inplace_concat` and
-      :attr:`sq_inplace_repeat`.
-
-
-   .. data:: Py_TPFLAGS_HAVE_RICHCOMPARE
-
-      If this bit is set, the type object has the :attr:`tp_richcompare` field, as
-      well as the :attr:`tp_traverse` and the :attr:`tp_clear` fields.
-
-
-   .. data:: Py_TPFLAGS_HAVE_WEAKREFS
-
-      If this bit is set, the :attr:`tp_weaklistoffset` field is defined.  Instances
-      of a type are weakly referenceable if the type's :attr:`tp_weaklistoffset` field
-      has a value greater than zero.
-
-
-   .. data:: Py_TPFLAGS_HAVE_ITER
-
-      If this bit is set, the type object has the :attr:`tp_iter` and
-      :attr:`tp_iternext` fields.
-
-
-   .. data:: Py_TPFLAGS_HAVE_CLASS
-
-      If this bit is set, the type object has several new fields defined starting in
-      Python 2.2: :attr:`tp_methods`, :attr:`tp_members`, :attr:`tp_getset`,
-      :attr:`tp_base`, :attr:`tp_dict`, :attr:`tp_descr_get`, :attr:`tp_descr_set`,
-      :attr:`tp_dictoffset`, :attr:`tp_init`, :attr:`tp_alloc`, :attr:`tp_new`,
-      :attr:`tp_free`, :attr:`tp_is_gc`, :attr:`tp_bases`, :attr:`tp_mro`,
-      :attr:`tp_cache`, :attr:`tp_subclasses`, and :attr:`tp_weaklist`.
-
-
-   .. data:: Py_TPFLAGS_HEAPTYPE
-
-      This bit is set when the type object itself is allocated on the heap.  In this
-      case, the :attr:`ob_type` field of its instances is considered a reference to
-      the type, and the type object is INCREF'ed when a new instance is created, and
-      DECREF'ed when an instance is destroyed (this does not apply to instances of
-      subtypes; only the type referenced by the instance's ob_type gets INCREF'ed or
-      DECREF'ed).
-
-
-   .. data:: Py_TPFLAGS_BASETYPE
-
-      This bit is set when the type can be used as the base type of another type.  If
-      this bit is clear, the type cannot be subtyped (similar to a "final" class in
-      Java).
-
-
-   .. data:: Py_TPFLAGS_READY
-
-      This bit is set when the type object has been fully initialized by
-      :cfunc:`PyType_Ready`.
-
-
-   .. data:: Py_TPFLAGS_READYING
-
-      This bit is set while :cfunc:`PyType_Ready` is in the process of initializing
-      the type object.
-
-
-   .. data:: Py_TPFLAGS_HAVE_GC
-
-      This bit is set when the object supports garbage collection.  If this bit
-      is set, instances must be created using :cfunc:`PyObject_GC_New` and
-      destroyed using :cfunc:`PyObject_GC_Del`.  More information in section
-      :ref:`supporting-cycle-detection`.  This bit also implies that the
-      GC-related fields :attr:`tp_traverse` and :attr:`tp_clear` are present in
-      the type object; but those fields also exist when
-      :const:`Py_TPFLAGS_HAVE_GC` is clear but
-      :const:`Py_TPFLAGS_HAVE_RICHCOMPARE` is set.
-
-
-   .. data:: Py_TPFLAGS_DEFAULT
-
-      This is a bitmask of all the bits that pertain to the existence of certain
-      fields in the type object and its extension structures. Currently, it includes
-      the following bits: :const:`Py_TPFLAGS_HAVE_GETCHARBUFFER`,
-      :const:`Py_TPFLAGS_HAVE_SEQUENCE_IN`, :const:`Py_TPFLAGS_HAVE_INPLACEOPS`,
-      :const:`Py_TPFLAGS_HAVE_RICHCOMPARE`, :const:`Py_TPFLAGS_HAVE_WEAKREFS`,
-      :const:`Py_TPFLAGS_HAVE_ITER`, and :const:`Py_TPFLAGS_HAVE_CLASS`.
-
-
-.. cmember:: char* PyTypeObject.tp_doc
-
-   An optional pointer to a NUL-terminated C string giving the docstring for this
-   type object.  This is exposed as the :attr:`__doc__` attribute on the type and
-   instances of the type.
-
-   This field is *not* inherited by subtypes.
-
-The following three fields only exist if the
-:const:`Py_TPFLAGS_HAVE_RICHCOMPARE` flag bit is set.
-
-
-.. cmember:: traverseproc PyTypeObject.tp_traverse
-
-   An optional pointer to a traversal function for the garbage collector.  This is
-   only used if the :const:`Py_TPFLAGS_HAVE_GC` flag bit is set.  More information
-   about Python's garbage collection scheme can be found in section
-   :ref:`supporting-cycle-detection`.
-
-   The :attr:`tp_traverse` pointer is used by the garbage collector to detect
-   reference cycles. A typical implementation of a :attr:`tp_traverse` function
-   simply calls :cfunc:`Py_VISIT` on each of the instance's members that are Python
-   objects.  For exampe, this is function :cfunc:`local_traverse` from the
-   :mod:`thread` extension module::
-
-      static int
-      local_traverse(localobject *self, visitproc visit, void *arg)
-      {
-          Py_VISIT(self->args);
-          Py_VISIT(self->kw);
-          Py_VISIT(self->dict);
-          return 0;
-      }
-
-   Note that :cfunc:`Py_VISIT` is called only on those members that can participate
-   in reference cycles.  Although there is also a ``self->key`` member, it can only
-   be *NULL* or a Python string and therefore cannot be part of a reference cycle.
-
-   On the other hand, even if you know a member can never be part of a cycle, as a
-   debugging aid you may want to visit it anyway just so the :mod:`gc` module's
-   :func:`get_referents` function will include it.
-
-   Note that :cfunc:`Py_VISIT` requires the *visit* and *arg* parameters to
-   :cfunc:`local_traverse` to have these specific names; don't name them just
-   anything.
-
-   This field is inherited by subtypes together with :attr:`tp_clear` and the
-   :const:`Py_TPFLAGS_HAVE_GC` flag bit: the flag bit, :attr:`tp_traverse`, and
-   :attr:`tp_clear` are all inherited from the base type if they are all zero in
-   the subtype *and* the subtype has the :const:`Py_TPFLAGS_HAVE_RICHCOMPARE` flag
-   bit set.
-
-
-.. cmember:: inquiry PyTypeObject.tp_clear
-
-   An optional pointer to a clear function for the garbage collector. This is only
-   used if the :const:`Py_TPFLAGS_HAVE_GC` flag bit is set.
-
-   The :attr:`tp_clear` member function is used to break reference cycles in cyclic
-   garbage detected by the garbage collector.  Taken together, all :attr:`tp_clear`
-   functions in the system must combine to break all reference cycles.  This is
-   subtle, and if in any doubt supply a :attr:`tp_clear` function.  For example,
-   the tuple type does not implement a :attr:`tp_clear` function, because it's
-   possible to prove that no reference cycle can be composed entirely of tuples.
-   Therefore the :attr:`tp_clear` functions of other types must be sufficient to
-   break any cycle containing a tuple.  This isn't immediately obvious, and there's
-   rarely a good reason to avoid implementing :attr:`tp_clear`.
-
-   Implementations of :attr:`tp_clear` should drop the instance's references to
-   those of its members that may be Python objects, and set its pointers to those
-   members to *NULL*, as in the following example::
-
-      static int
-      local_clear(localobject *self)
-      {
-          Py_CLEAR(self->key);
-          Py_CLEAR(self->args);
-          Py_CLEAR(self->kw);
-          Py_CLEAR(self->dict);
-          return 0;
-      }
-
-   The :cfunc:`Py_CLEAR` macro should be used, because clearing references is
-   delicate:  the reference to the contained object must not be decremented until
-   after the pointer to the contained object is set to *NULL*.  This is because
-   decrementing the reference count may cause the contained object to become trash,
-   triggering a chain of reclamation activity that may include invoking arbitrary
-   Python code (due to finalizers, or weakref callbacks, associated with the
-   contained object). If it's possible for such code to reference *self* again,
-   it's important that the pointer to the contained object be *NULL* at that time,
-   so that *self* knows the contained object can no longer be used.  The
-   :cfunc:`Py_CLEAR` macro performs the operations in a safe order.
-
-   Because the goal of :attr:`tp_clear` functions is to break reference cycles,
-   it's not necessary to clear contained objects like Python strings or Python
-   integers, which can't participate in reference cycles. On the other hand, it may
-   be convenient to clear all contained Python objects, and write the type's
-   :attr:`tp_dealloc` function to invoke :attr:`tp_clear`.
-
-   More information about Python's garbage collection scheme can be found in
-   section :ref:`supporting-cycle-detection`.
-
-   This field is inherited by subtypes together with :attr:`tp_traverse` and the
-   :const:`Py_TPFLAGS_HAVE_GC` flag bit: the flag bit, :attr:`tp_traverse`, and
-   :attr:`tp_clear` are all inherited from the base type if they are all zero in
-   the subtype *and* the subtype has the :const:`Py_TPFLAGS_HAVE_RICHCOMPARE` flag
-   bit set.
-
-
-.. cmember:: richcmpfunc PyTypeObject.tp_richcompare
-
-   An optional pointer to the rich comparison function.
-
-   The signature is the same as for :cfunc:`PyObject_RichCompare`. The function
-   should return the result of the comparison (usually ``Py_True`` or
-   ``Py_False``).  If the comparison is undefined, it must return
-   ``Py_NotImplemented``, if another error occurred it must return ``NULL`` and set
-   an exception condition.
-
-   This field is inherited by subtypes together with :attr:`tp_compare` and
-   :attr:`tp_hash`: a subtype inherits all three of :attr:`tp_compare`,
-   :attr:`tp_richcompare`, and :attr:`tp_hash`, when the subtype's
-   :attr:`tp_compare`, :attr:`tp_richcompare`, and :attr:`tp_hash` are all *NULL*.
-
-   The following constants are defined to be used as the third argument for
-   :attr:`tp_richcompare` and for :cfunc:`PyObject_RichCompare`:
-
-   +----------------+------------+
-   | Constant       | Comparison |
-   +================+============+
-   | :const:`Py_LT` | ``<``      |
-   +----------------+------------+
-   | :const:`Py_LE` | ``<=``     |
-   +----------------+------------+
-   | :const:`Py_EQ` | ``==``     |
-   +----------------+------------+
-   | :const:`Py_NE` | ``!=``     |
-   +----------------+------------+
-   | :const:`Py_GT` | ``>``      |
-   +----------------+------------+
-   | :const:`Py_GE` | ``>=``     |
-   +----------------+------------+
-
-The next field only exists if the :const:`Py_TPFLAGS_HAVE_WEAKREFS` flag bit is
-set.
-
-
-.. cmember:: long PyTypeObject.tp_weaklistoffset
-
-   If the instances of this type are weakly referenceable, this field is greater
-   than zero and contains the offset in the instance structure of the weak
-   reference list head (ignoring the GC header, if present); this offset is used by
-   :cfunc:`PyObject_ClearWeakRefs` and the :cfunc:`PyWeakref_\*` functions.  The
-   instance structure needs to include a field of type :ctype:`PyObject\*` which is
-   initialized to *NULL*.
-
-   Do not confuse this field with :attr:`tp_weaklist`; that is the list head for
-   weak references to the type object itself.
-
-   This field is inherited by subtypes, but see the rules listed below. A subtype
-   may override this offset; this means that the subtype uses a different weak
-   reference list head than the base type.  Since the list head is always found via
-   :attr:`tp_weaklistoffset`, this should not be a problem.
-
-   When a type defined by a class statement has no :attr:`__slots__` declaration,
-   and none of its base types are weakly referenceable, the type is made weakly
-   referenceable by adding a weak reference list head slot to the instance layout
-   and setting the :attr:`tp_weaklistoffset` of that slot's offset.
-
-   When a type's :attr:`__slots__` declaration contains a slot named
-   :attr:`__weakref__`, that slot becomes the weak reference list head for
-   instances of the type, and the slot's offset is stored in the type's
-   :attr:`tp_weaklistoffset`.
-
-   When a type's :attr:`__slots__` declaration does not contain a slot named
-   :attr:`__weakref__`, the type inherits its :attr:`tp_weaklistoffset` from its
-   base type.
-
-The next two fields only exist if the :const:`Py_TPFLAGS_HAVE_CLASS` flag bit is
-set.
-
-
-.. cmember:: getiterfunc PyTypeObject.tp_iter
-
-   An optional pointer to a function that returns an iterator for the object.  Its
-   presence normally signals that the instances of this type are iterable (although
-   sequences may be iterable without this function, and classic instances always
-   have this function, even if they don't define an :meth:`__iter__` method).
-
-   This function has the same signature as :cfunc:`PyObject_GetIter`.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: iternextfunc PyTypeObject.tp_iternext
-
-   An optional pointer to a function that returns the next item in an iterator, or
-   raises :exc:`StopIteration` when the iterator is exhausted.  Its presence
-   normally signals that the instances of this type are iterators (although classic
-   instances always have this function, even if they don't define a
-   :meth:`__next__` method).
-
-   Iterator types should also define the :attr:`tp_iter` function, and that
-   function should return the iterator instance itself (not a new iterator
-   instance).
-
-   This function has the same signature as :cfunc:`PyIter_Next`.
-
-   This field is inherited by subtypes.
-
-The next fields, up to and including :attr:`tp_weaklist`, only exist if the
-:const:`Py_TPFLAGS_HAVE_CLASS` flag bit is set.
-
-
-.. cmember:: struct PyMethodDef* PyTypeObject.tp_methods
-
-   An optional pointer to a static *NULL*-terminated array of :ctype:`PyMethodDef`
-   structures, declaring regular methods of this type.
-
-   For each entry in the array, an entry is added to the type's dictionary (see
-   :attr:`tp_dict` below) containing a method descriptor.
-
-   This field is not inherited by subtypes (methods are inherited through a
-   different mechanism).
-
-
-.. cmember:: struct PyMemberDef* PyTypeObject.tp_members
-
-   An optional pointer to a static *NULL*-terminated array of :ctype:`PyMemberDef`
-   structures, declaring regular data members (fields or slots) of instances of
-   this type.
-
-   For each entry in the array, an entry is added to the type's dictionary (see
-   :attr:`tp_dict` below) containing a member descriptor.
-
-   This field is not inherited by subtypes (members are inherited through a
-   different mechanism).
-
-
-.. cmember:: struct PyGetSetDef* PyTypeObject.tp_getset
-
-   An optional pointer to a static *NULL*-terminated array of :ctype:`PyGetSetDef`
-   structures, declaring computed attributes of instances of this type.
-
-   For each entry in the array, an entry is added to the type's dictionary (see
-   :attr:`tp_dict` below) containing a getset descriptor.
-
-   This field is not inherited by subtypes (computed attributes are inherited
-   through a different mechanism).
-
-   Docs for PyGetSetDef (XXX belong elsewhere)::
-
-      typedef PyObject *(*getter)(PyObject *, void *);
-      typedef int (*setter)(PyObject *, PyObject *, void *);
-
-      typedef struct PyGetSetDef {
-          char *name;    /* attribute name */
-          getter get;    /* C function to get the attribute */
-          setter set;    /* C function to set the attribute */
-          char *doc;     /* optional doc string */
-          void *closure; /* optional additional data for getter and setter */
-      } PyGetSetDef;
-
-
-.. cmember:: PyTypeObject* PyTypeObject.tp_base
-
-   An optional pointer to a base type from which type properties are inherited.  At
-   this level, only single inheritance is supported; multiple inheritance require
-   dynamically creating a type object by calling the metatype.
-
-   This field is not inherited by subtypes (obviously), but it defaults to
-   ``&PyBaseObject_Type`` (which to Python programmers is known as the type
-   :class:`object`).
-
-
-.. cmember:: PyObject* PyTypeObject.tp_dict
-
-   The type's dictionary is stored here by :cfunc:`PyType_Ready`.
-
-   This field should normally be initialized to *NULL* before PyType_Ready is
-   called; it may also be initialized to a dictionary containing initial attributes
-   for the type.  Once :cfunc:`PyType_Ready` has initialized the type, extra
-   attributes for the type may be added to this dictionary only if they don't
-   correspond to overloaded operations (like :meth:`__add__`).
-
-   This field is not inherited by subtypes (though the attributes defined in here
-   are inherited through a different mechanism).
-
-
-.. cmember:: descrgetfunc PyTypeObject.tp_descr_get
-
-   An optional pointer to a "descriptor get" function.
-
-   The function signature is ::
-
-      PyObject * tp_descr_get(PyObject *self, PyObject *obj, PyObject *type);
-
-   XXX explain.
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: descrsetfunc PyTypeObject.tp_descr_set
-
-   An optional pointer to a "descriptor set" function.
-
-   The function signature is ::
-
-      int tp_descr_set(PyObject *self, PyObject *obj, PyObject *value);
-
-   This field is inherited by subtypes.
-
-   XXX explain.
-
-
-.. cmember:: long PyTypeObject.tp_dictoffset
-
-   If the instances of this type have a dictionary containing instance variables,
-   this field is non-zero and contains the offset in the instances of the type of
-   the instance variable dictionary; this offset is used by
-   :cfunc:`PyObject_GenericGetAttr`.
-
-   Do not confuse this field with :attr:`tp_dict`; that is the dictionary for
-   attributes of the type object itself.
-
-   If the value of this field is greater than zero, it specifies the offset from
-   the start of the instance structure.  If the value is less than zero, it
-   specifies the offset from the *end* of the instance structure.  A negative
-   offset is more expensive to use, and should only be used when the instance
-   structure contains a variable-length part.  This is used for example to add an
-   instance variable dictionary to subtypes of :class:`str` or :class:`tuple`. Note
-   that the :attr:`tp_basicsize` field should account for the dictionary added to
-   the end in that case, even though the dictionary is not included in the basic
-   object layout.  On a system with a pointer size of 4 bytes,
-   :attr:`tp_dictoffset` should be set to ``-4`` to indicate that the dictionary is
-   at the very end of the structure.
-
-   The real dictionary offset in an instance can be computed from a negative
-   :attr:`tp_dictoffset` as follows::
-
-      dictoffset = tp_basicsize + abs(ob_size)*tp_itemsize + tp_dictoffset
-      if dictoffset is not aligned on sizeof(void*):
-          round up to sizeof(void*)
-
-   where :attr:`tp_basicsize`, :attr:`tp_itemsize` and :attr:`tp_dictoffset` are
-   taken from the type object, and :attr:`ob_size` is taken from the instance.  The
-   absolute value is taken because long ints use the sign of :attr:`ob_size` to
-   store the sign of the number.  (There's never a need to do this calculation
-   yourself; it is done for you by :cfunc:`_PyObject_GetDictPtr`.)
-
-   This field is inherited by subtypes, but see the rules listed below. A subtype
-   may override this offset; this means that the subtype instances store the
-   dictionary at a difference offset than the base type.  Since the dictionary is
-   always found via :attr:`tp_dictoffset`, this should not be a problem.
-
-   When a type defined by a class statement has no :attr:`__slots__` declaration,
-   and none of its base types has an instance variable dictionary, a dictionary
-   slot is added to the instance layout and the :attr:`tp_dictoffset` is set to
-   that slot's offset.
-
-   When a type defined by a class statement has a :attr:`__slots__` declaration,
-   the type inherits its :attr:`tp_dictoffset` from its base type.
-
-   (Adding a slot named :attr:`__dict__` to the :attr:`__slots__` declaration does
-   not have the expected effect, it just causes confusion.  Maybe this should be
-   added as a feature just like :attr:`__weakref__` though.)
-
-
-.. cmember:: initproc PyTypeObject.tp_init
-
-   An optional pointer to an instance initialization function.
-
-   This function corresponds to the :meth:`__init__` method of classes.  Like
-   :meth:`__init__`, it is possible to create an instance without calling
-   :meth:`__init__`, and it is possible to reinitialize an instance by calling its
-   :meth:`__init__` method again.
-
-   The function signature is ::
-
-      int tp_init(PyObject *self, PyObject *args, PyObject *kwds)
-
-   The self argument is the instance to be initialized; the *args* and *kwds*
-   arguments represent positional and keyword arguments of the call to
-   :meth:`__init__`.
-
-   The :attr:`tp_init` function, if not *NULL*, is called when an instance is
-   created normally by calling its type, after the type's :attr:`tp_new` function
-   has returned an instance of the type.  If the :attr:`tp_new` function returns an
-   instance of some other type that is not a subtype of the original type, no
-   :attr:`tp_init` function is called; if :attr:`tp_new` returns an instance of a
-   subtype of the original type, the subtype's :attr:`tp_init` is called.  (VERSION
-   NOTE: described here is what is implemented in Python 2.2.1 and later.  In
-   Python 2.2, the :attr:`tp_init` of the type of the object returned by
-   :attr:`tp_new` was always called, if not *NULL*.)
-
-   This field is inherited by subtypes.
-
-
-.. cmember:: allocfunc PyTypeObject.tp_alloc
-
-   An optional pointer to an instance allocation function.
-
-   The function signature is ::
-
-      PyObject *tp_alloc(PyTypeObject *self, Py_ssize_t nitems)
-
-   The purpose of this function is to separate memory allocation from memory
-   initialization.  It should return a pointer to a block of memory of adequate
-   length for the instance, suitably aligned, and initialized to zeros, but with
-   :attr:`ob_refcnt` set to ``1`` and :attr:`ob_type` set to the type argument.  If
-   the type's :attr:`tp_itemsize` is non-zero, the object's :attr:`ob_size` field
-   should be initialized to *nitems* and the length of the allocated memory block
-   should be ``tp_basicsize + nitems*tp_itemsize``, rounded up to a multiple of
-   ``sizeof(void*)``; otherwise, *nitems* is not used and the length of the block
-   should be :attr:`tp_basicsize`.
-
-   Do not use this function to do any other instance initialization, not even to
-   allocate additional memory; that should be done by :attr:`tp_new`.
-
-   This field is inherited by static subtypes, but not by dynamic subtypes
-   (subtypes created by a class statement); in the latter, this field is always set
-   to :cfunc:`PyType_GenericAlloc`, to force a standard heap allocation strategy.
-   That is also the recommended value for statically defined types.
-
-
-.. cmember:: newfunc PyTypeObject.tp_new
-
-   An optional pointer to an instance creation function.
-
-   If this function is *NULL* for a particular type, that type cannot be called to
-   create new instances; presumably there is some other way to create instances,
-   like a factory function.
-
-   The function signature is ::
-
-      PyObject *tp_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
-
-   The subtype argument is the type of the object being created; the *args* and
-   *kwds* arguments represent positional and keyword arguments of the call to the
-   type.  Note that subtype doesn't have to equal the type whose :attr:`tp_new`
-   function is called; it may be a subtype of that type (but not an unrelated
-   type).
-
-   The :attr:`tp_new` function should call ``subtype->tp_alloc(subtype, nitems)``
-   to allocate space for the object, and then do only as much further
-   initialization as is absolutely necessary.  Initialization that can safely be
-   ignored or repeated should be placed in the :attr:`tp_init` handler.  A good
-   rule of thumb is that for immutable types, all initialization should take place
-   in :attr:`tp_new`, while for mutable types, most initialization should be
-   deferred to :attr:`tp_init`.
-
-   This field is inherited by subtypes, except it is not inherited by static types
-   whose :attr:`tp_base` is *NULL* or ``&PyBaseObject_Type``.  The latter exception
-   is a precaution so that old extension types don't become callable simply by
-   being linked with Python 2.2.
-
-
-.. cmember:: destructor PyTypeObject.tp_free
-
-   An optional pointer to an instance deallocation function.
-
-   The signature of this function has changed slightly: in Python 2.2 and 2.2.1,
-   its signature is :ctype:`destructor`::
-
-      void tp_free(PyObject *)
-
-   In Python 2.3 and beyond, its signature is :ctype:`freefunc`::
-
-      void tp_free(void *)
-
-   The only initializer that is compatible with both versions is ``PyObject_Free``,
-   whose definition has suitably adapted in Python 2.3.
-
-   This field is inherited by static subtypes, but not by dynamic subtypes
-   (subtypes created by a class statement); in the latter, this field is set to a
-   deallocator suitable to match :cfunc:`PyType_GenericAlloc` and the value of the
-   :const:`Py_TPFLAGS_HAVE_GC` flag bit.
-
-
-.. cmember:: inquiry PyTypeObject.tp_is_gc
-
-   An optional pointer to a function called by the garbage collector.
-
-   The garbage collector needs to know whether a particular object is collectible
-   or not.  Normally, it is sufficient to look at the object's type's
-   :attr:`tp_flags` field, and check the :const:`Py_TPFLAGS_HAVE_GC` flag bit.  But
-   some types have a mixture of statically and dynamically allocated instances, and
-   the statically allocated instances are not collectible.  Such types should
-   define this function; it should return ``1`` for a collectible instance, and
-   ``0`` for a non-collectible instance. The signature is ::
-
-      int tp_is_gc(PyObject *self)
-
-   (The only example of this are types themselves.  The metatype,
-   :cdata:`PyType_Type`, defines this function to distinguish between statically
-   and dynamically allocated types.)
-
-   This field is inherited by subtypes.  (VERSION NOTE: in Python 2.2, it was not
-   inherited.  It is inherited in 2.2.1 and later versions.)
-
-
-.. cmember:: PyObject* PyTypeObject.tp_bases
-
-   Tuple of base types.
-
-   This is set for types created by a class statement.  It should be *NULL* for
-   statically defined types.
-
-   This field is not inherited.
-
-
-.. cmember:: PyObject* PyTypeObject.tp_mro
-
-   Tuple containing the expanded set of base types, starting with the type itself
-   and ending with :class:`object`, in Method Resolution Order.
-
-   This field is not inherited; it is calculated fresh by :cfunc:`PyType_Ready`.
-
-
-.. cmember:: PyObject* PyTypeObject.tp_cache
-
-   Unused.  Not inherited.  Internal use only.
-
-
-.. cmember:: PyObject* PyTypeObject.tp_subclasses
-
-   List of weak references to subclasses.  Not inherited.  Internal use only.
-
-
-.. cmember:: PyObject* PyTypeObject.tp_weaklist
-
-   Weak reference list head, for weak references to this type object.  Not
-   inherited.  Internal use only.
-
-The remaining fields are only defined if the feature test macro
-:const:`COUNT_ALLOCS` is defined, and are for internal use only. They are
-documented here for completeness.  None of these fields are inherited by
-subtypes.
-
-
-.. cmember:: Py_ssize_t PyTypeObject.tp_allocs
-
-   Number of allocations.
-
-
-.. cmember:: Py_ssize_t PyTypeObject.tp_frees
-
-   Number of frees.
-
-
-.. cmember:: Py_ssize_t PyTypeObject.tp_maxalloc
-
-   Maximum simultaneously allocated objects.
-
-
-.. cmember:: PyTypeObject* PyTypeObject.tp_next
-
-   Pointer to the next type object with a non-zero :attr:`tp_allocs` field.
-
-Also, note that, in a garbage collected Python, tp_dealloc may be called from
-any Python thread, not just the thread which created the object (if the object
-becomes part of a refcount cycle, that cycle might be collected by a garbage
-collection on any thread).  This is not a problem for Python API calls, since
-the thread on which tp_dealloc is called will own the Global Interpreter Lock
-(GIL). However, if the object being destroyed in turn destroys objects from some
-other C or C++ library, care should be taken to ensure that destroying those
-objects on the thread which called tp_dealloc will not violate any assumptions
-of the library.
-
-
-.. _number-structs:
-
-Number Object Structures
-========================
-
-.. sectionauthor:: Amaury Forgeot d'Arc
-
-
-.. ctype:: PyNumberMethods
-
-   This structure holds pointers to the functions which an object uses to
-   implement the number protocol.  Each function is used by the function of
-   similar name documented in the :ref:`number` section.
-
-   Here is the structure definition::
-
-       typedef struct {
-            binaryfunc nb_add;
-            binaryfunc nb_subtract;
-            binaryfunc nb_multiply;
-            binaryfunc nb_remainder;
-            binaryfunc nb_divmod;
-            ternaryfunc nb_power;
-            unaryfunc nb_negative;
-            unaryfunc nb_positive;
-            unaryfunc nb_absolute;
-            inquiry nb_bool;
-            unaryfunc nb_invert;
-            binaryfunc nb_lshift;
-            binaryfunc nb_rshift;
-            binaryfunc nb_and;
-            binaryfunc nb_xor;
-            binaryfunc nb_or;
-            int nb_reserved;  /* unused, must be zero */
-            unaryfunc nb_int;
-            unaryfunc nb_long;
-            unaryfunc nb_float;
-            
-            unaryfunc nb_oct; /* not used anymore, must be zero */
-            unaryfunc nb_hex; /* not used anymore, must be zero */
-
-            binaryfunc nb_inplace_add;
-            binaryfunc nb_inplace_subtract;
-            binaryfunc nb_inplace_multiply;
-            binaryfunc nb_inplace_remainder;
-            ternaryfunc nb_inplace_power;
-            binaryfunc nb_inplace_lshift;
-            binaryfunc nb_inplace_rshift;
-            binaryfunc nb_inplace_and;
-            binaryfunc nb_inplace_xor;
-            binaryfunc nb_inplace_or;
-
-            binaryfunc nb_floor_divide;
-            binaryfunc nb_true_divide;
-            binaryfunc nb_inplace_floor_divide;
-            binaryfunc nb_inplace_true_divide;
-
-            unaryfunc nb_index;
-       } PyNumberMethods;
-
-   .. note::
-
-      Binary and ternary functions must check the type of all their operands,
-      and implement the necessary conversions (at least one of the operands is
-      an instance of the defined type).  If the operation is not defined for the
-      given operands, binary and ternary functions must return
-      ``Py_NotImplemented``, if another error occurred they must return ``NULL``
-      and set an exception.
-
-
-.. _mapping-structs:
-
-Mapping Object Structures
-=========================
-
-.. sectionauthor:: Amaury Forgeot d'Arc
-
-
-.. ctype:: PyMappingMethods
-
-   This structure holds pointers to the functions which an object uses to
-   implement the mapping protocol.  It has three members:
-
-.. cmember:: lenfunc PyMappingMethods.mp_length
-
-   This function is used by :cfunc:`PyMapping_Length` and
-   :cfunc:`PyObject_Size`, and has the same signature.  This slot may be set to
-   *NULL* if the object has no defined length.
-
-.. cmember:: binaryfunc PyMappingMethods.mp_subscript
-
-   This function is used by :cfunc:`PyObject_GetItem` and has the same
-   signature.  This slot must be filled for the :cfunc:`PyMapping_Check`
-   function to return ``1``, it can be *NULL* otherwise.
-
-.. cmember:: objobjargproc PyMappingMethods.mp_ass_subscript
-
-   This function is used by :cfunc:`PyObject_SetItem` and has the same
-   signature.  If this slot is *NULL*, the object does not support item
-   assignment.
-
-
-.. _sequence-structs:
-
-Sequence Object Structures
-==========================
-
-.. sectionauthor:: Amaury Forgeot d'Arc
-
-
-.. ctype:: PySequenceMethods
-
-   This structure holds pointers to the functions which an object uses to
-   implement the sequence protocol.
-
-.. cmember:: lenfunc PySequenceMethods.sq_length
-
-   This function is used by :cfunc:`PySequence_Size` and :cfunc:`PyObject_Size`,
-   and has the same signature.
-
-.. cmember:: binaryfunc PySequenceMethods.sq_concat
-
-   This function is used by :cfunc:`PySequence_Concat` and has the same
-   signature.  It is also used by the ``+`` operator, after trying the numeric
-   addition via the :attr:`tp_as_number.nb_add` slot.
-
-.. cmember:: ssizeargfunc PySequenceMethods.sq_repeat
-
-   This function is used by :cfunc:`PySequence_Repeat` and has the same
-   signature.  It is also used by the ``*`` operator, after trying numeric
-   multiplication via the :attr:`tp_as_number.nb_mul` slot.
-
-.. cmember:: ssizeargfunc PySequenceMethods.sq_item
-
-   This function is used by :cfunc:`PySequence_GetItem` and has the same
-   signature.  This slot must be filled for the :cfunc:`PySequence_Check`
-   function to return ``1``, it can be *NULL* otherwise.
-
-   Negative indexes are handled as follows: if the :attr:`sq_length` slot is
-   filled, it is called and the sequence length is used to compute a positive
-   index which is passed to :attr:`sq_item`.  If :attr:`sq_length` is *NULL*,
-   the index is passed as is to the function.
-
-.. cmember:: ssizeobjargproc PySequenceMethods.sq_ass_item
-
-   This function is used by :cfunc:`PySequence_SetItem` and has the same
-   signature.  This slot may be left to *NULL* if the object does not support
-   item assignment.
-
-.. cmember:: objobjproc PySequenceMethods.sq_contains
-
-   This function may be used by :cfunc:`PySequence_Contains` and has the same
-   signature.  This slot may be left to *NULL*, in this case
-   :cfunc:`PySequence_Contains` simply traverses the sequence until it finds a
-   match.
-
-.. cmember:: binaryfunc PySequenceMethods.sq_inplace_concat
-
-   This function is used by :cfunc:`PySequence_InPlaceConcat` and has the same
-   signature.  It should modify its first operand, and return it.
-
-.. cmember:: ssizeargfunc PySequenceMethods.sq_inplace_repeat
-
-   This function is used by :cfunc:`PySequence_InPlaceRepeat` and has the same
-   signature.  It should modify its first operand, and return it.
-
-.. XXX need to explain precedence between mapping and sequence
-.. XXX explains when to implement the sq_inplace_* slots
-
-
-.. _buffer-structs:
-
-Buffer Object Structures
-========================
-
-.. sectionauthor:: Greg J. Stein <greg@lyra.org>
-
-
-The buffer interface exports a model where an object can expose its internal
-data as a set of chunks of data, where each chunk is specified as a
-pointer/length pair.  These chunks are called :dfn:`segments` and are presumed
-to be non-contiguous in memory.
-
-If an object does not export the buffer interface, then its :attr:`tp_as_buffer`
-member in the :ctype:`PyTypeObject` structure should be *NULL*.  Otherwise, the
-:attr:`tp_as_buffer` will point to a :ctype:`PyBufferProcs` structure.
-
-.. note::
-
-   It is very important that your :ctype:`PyTypeObject` structure uses
-   :const:`Py_TPFLAGS_DEFAULT` for the value of the :attr:`tp_flags` member rather
-   than ``0``.  This tells the Python runtime that your :ctype:`PyBufferProcs`
-   structure contains the :attr:`bf_getcharbuffer` slot. Older versions of Python
-   did not have this member, so a new Python interpreter using an old extension
-   needs to be able to test for its presence before using it.
-
-
-.. ctype:: PyBufferProcs
-
-   Structure used to hold the function pointers which define an implementation of
-   the buffer protocol.
-
-   The first slot is :attr:`bf_getreadbuffer`, of type :ctype:`getreadbufferproc`.
-   If this slot is *NULL*, then the object does not support reading from the
-   internal data.  This is non-sensical, so implementors should fill this in, but
-   callers should test that the slot contains a non-*NULL* value.
-
-   The next slot is :attr:`bf_getwritebuffer` having type
-   :ctype:`getwritebufferproc`.  This slot may be *NULL* if the object does not
-   allow writing into its returned buffers.
-
-   The third slot is :attr:`bf_getsegcount`, with type :ctype:`getsegcountproc`.
-   This slot must not be *NULL* and is used to inform the caller how many segments
-   the object contains.  Simple objects such as :ctype:`PyString_Type` and
-   :ctype:`PyBuffer_Type` objects contain a single segment.
-
-   .. index:: single: PyType_HasFeature()
-
-   The last slot is :attr:`bf_getcharbuffer`, of type :ctype:`getcharbufferproc`.
-   This slot will only be present if the :const:`Py_TPFLAGS_HAVE_GETCHARBUFFER`
-   flag is present in the :attr:`tp_flags` field of the object's
-   :ctype:`PyTypeObject`. Before using this slot, the caller should test whether it
-   is present by using the :cfunc:`PyType_HasFeature` function.  If the flag is
-   present, :attr:`bf_getcharbuffer` may be *NULL*, indicating that the object's
-   contents cannot be used as *8-bit characters*. The slot function may also raise
-   an error if the object's contents cannot be interpreted as 8-bit characters.
-   For example, if the object is an array which is configured to hold floating
-   point values, an exception may be raised if a caller attempts to use
-   :attr:`bf_getcharbuffer` to fetch a sequence of 8-bit characters. This notion of
-   exporting the internal buffers as "text" is used to distinguish between objects
-   that are binary in nature, and those which have character-based content.
-
-   .. note::
-
-      The current policy seems to state that these characters may be multi-byte
-      characters. This implies that a buffer size of *N* does not mean there are *N*
-      characters present.
-
-
-.. data:: Py_TPFLAGS_HAVE_GETCHARBUFFER
-
-   Flag bit set in the type structure to indicate that the :attr:`bf_getcharbuffer`
-   slot is known.  This being set does not indicate that the object supports the
-   buffer interface or that the :attr:`bf_getcharbuffer` slot is non-*NULL*.
-
-
-.. ctype:: Py_ssize_t (*readbufferproc) (PyObject *self, Py_ssize_t segment, void **ptrptr)
-
-   Return a pointer to a readable segment of the buffer in ``*ptrptr``.  This
-   function is allowed to raise an exception, in which case it must return ``-1``.
-   The *segment* which is specified must be zero or positive, and strictly less
-   than the number of segments returned by the :attr:`bf_getsegcount` slot
-   function.  On success, it returns the length of the segment, and sets
-   ``*ptrptr`` to a pointer to that memory.
-
-
-.. ctype:: Py_ssize_t (*writebufferproc) (PyObject *self, Py_ssize_t segment, void **ptrptr)
-
-   Return a pointer to a writable memory buffer in ``*ptrptr``, and the length of
-   that segment as the function return value.  The memory buffer must correspond to
-   buffer segment *segment*.  Must return ``-1`` and set an exception on error.
-   :exc:`TypeError` should be raised if the object only supports read-only buffers,
-   and :exc:`SystemError` should be raised when *segment* specifies a segment that
-   doesn't exist.
-
-   .. Why doesn't it raise ValueError for this one?
-      GJS: because you shouldn't be calling it with an invalid
-      segment. That indicates a blatant programming error in the C code.
-
-
-.. ctype:: Py_ssize_t (*segcountproc) (PyObject *self, Py_ssize_t *lenp)
-
-   Return the number of memory segments which comprise the buffer.  If *lenp* is
-   not *NULL*, the implementation must report the sum of the sizes (in bytes) of
-   all segments in ``*lenp``. The function cannot fail.
-
-
-.. ctype:: Py_ssize_t (*charbufferproc) (PyObject *self, Py_ssize_t segment, const char **ptrptr)
-
-   Return the size of the segment *segment* that *ptrptr*  is set to.  ``*ptrptr``
-   is set to the memory buffer. Returns ``-1`` on error.
-
-
-.. _supporting-iteration:
-
-Supporting the Iterator Protocol
-================================
-
-
-.. _supporting-cycle-detection:
-
-Supporting Cyclic Garbage Collection
-====================================
-
-Python's support for detecting and collecting garbage which involves circular
-references requires support from object types which are "containers" for other
-objects which may also be containers.  Types which do not store references to
-other objects, or which only store references to atomic types (such as numbers
-or strings), do not need to provide any explicit support for garbage collection.
-
-To create a container type, the :attr:`tp_flags` field of the type object must
-include the :const:`Py_TPFLAGS_HAVE_GC` and provide an implementation of the
-:attr:`tp_traverse` handler.  If instances of the type are mutable, a
-:attr:`tp_clear` implementation must also be provided.
-
-
-.. data:: Py_TPFLAGS_HAVE_GC
-
-   Objects with a type with this flag set must conform with the rules documented
-   here.  For convenience these objects will be referred to as container objects.
-
-Constructors for container types must conform to two rules:
-
-#. The memory for the object must be allocated using :cfunc:`PyObject_GC_New` or
-   :cfunc:`PyObject_GC_VarNew`.
-
-#. Once all the fields which may contain references to other containers are
-   initialized, it must call :cfunc:`PyObject_GC_Track`.
-
-
-.. cfunction:: TYPE* PyObject_GC_New(TYPE, PyTypeObject *type)
-
-   Analogous to :cfunc:`PyObject_New` but for container objects with the
-   :const:`Py_TPFLAGS_HAVE_GC` flag set.
-
-
-.. cfunction:: TYPE* PyObject_GC_NewVar(TYPE, PyTypeObject *type, Py_ssize_t size)
-
-   Analogous to :cfunc:`PyObject_NewVar` but for container objects with the
-   :const:`Py_TPFLAGS_HAVE_GC` flag set.
-
-
-.. cfunction:: PyVarObject * PyObject_GC_Resize(PyVarObject *op, Py_ssize_t)
-
-   Resize an object allocated by :cfunc:`PyObject_NewVar`.  Returns the resized
-   object or *NULL* on failure.
-
-
-.. cfunction:: void PyObject_GC_Track(PyObject *op)
-
-   Adds the object *op* to the set of container objects tracked by the collector.
-   The collector can run at unexpected times so objects must be valid while being
-   tracked.  This should be called once all the fields followed by the
-   :attr:`tp_traverse` handler become valid, usually near the end of the
-   constructor.
-
-
-.. cfunction:: void _PyObject_GC_TRACK(PyObject *op)
-
-   A macro version of :cfunc:`PyObject_GC_Track`.  It should not be used for
-   extension modules.
-
-Similarly, the deallocator for the object must conform to a similar pair of
-rules:
-
-#. Before fields which refer to other containers are invalidated,
-   :cfunc:`PyObject_GC_UnTrack` must be called.
-
-#. The object's memory must be deallocated using :cfunc:`PyObject_GC_Del`.
-
-
-.. cfunction:: void PyObject_GC_Del(void *op)
-
-   Releases memory allocated to an object using :cfunc:`PyObject_GC_New` or
-   :cfunc:`PyObject_GC_NewVar`.
-
-
-.. cfunction:: void PyObject_GC_UnTrack(void *op)
-
-   Remove the object *op* from the set of container objects tracked by the
-   collector.  Note that :cfunc:`PyObject_GC_Track` can be called again on this
-   object to add it back to the set of tracked objects.  The deallocator
-   (:attr:`tp_dealloc` handler) should call this for the object before any of the
-   fields used by the :attr:`tp_traverse` handler become invalid.
-
-
-.. cfunction:: void _PyObject_GC_UNTRACK(PyObject *op)
-
-   A macro version of :cfunc:`PyObject_GC_UnTrack`.  It should not be used for
-   extension modules.
-
-The :attr:`tp_traverse` handler accepts a function parameter of this type:
-
-
-.. ctype:: int (*visitproc)(PyObject *object, void *arg)
-
-   Type of the visitor function passed to the :attr:`tp_traverse` handler.  The
-   function should be called with an object to traverse as *object* and the third
-   parameter to the :attr:`tp_traverse` handler as *arg*.  The Python core uses
-   several visitor functions to implement cyclic garbage detection; it's not
-   expected that users will need to write their own visitor functions.
-
-The :attr:`tp_traverse` handler must have the following type:
-
-
-.. ctype:: int (*traverseproc)(PyObject *self, visitproc visit, void *arg)
-
-   Traversal function for a container object.  Implementations must call the
-   *visit* function for each object directly contained by *self*, with the
-   parameters to *visit* being the contained object and the *arg* value passed to
-   the handler.  The *visit* function must not be called with a *NULL* object
-   argument.  If *visit* returns a non-zero value that value should be returned
-   immediately.
-
-To simplify writing :attr:`tp_traverse` handlers, a :cfunc:`Py_VISIT` macro is
-provided.  In order to use this macro, the :attr:`tp_traverse` implementation
-must name its arguments exactly *visit* and *arg*:
-
-
-.. cfunction:: void Py_VISIT(PyObject *o)
-
-   Call the *visit* callback, with arguments *o* and *arg*. If *visit* returns a
-   non-zero value, then return it.  Using this macro, :attr:`tp_traverse` handlers
-   look like::
-
-      static int
-      my_traverse(Noddy *self, visitproc visit, void *arg)
-      {
-          Py_VISIT(self->foo);
-          Py_VISIT(self->bar);
-          return 0;
-      }
-
-The :attr:`tp_clear` handler must be of the :ctype:`inquiry` type, or *NULL* if
-the object is immutable.
-
-
-.. ctype:: int (*inquiry)(PyObject *self)
-
-   Drop references that may have created reference cycles.  Immutable objects do
-   not have to define this method since they can never directly create reference
-   cycles.  Note that the object must still be valid after calling this method
-   (don't just call :cfunc:`Py_DECREF` on a reference).  The collector will call
-   this method if it detects that this object is involved in a reference cycle.
-

File Doc/library/optparse.rst

   default value.  If an option has no default value (or the default value is
   ``None``), ``%default`` expands to ``none``.
 
+When dealing with many options, it is convenient to group these
+options for better help output.  An :class:`OptionParser` can contain
+several option groups, each of which can contain several options.
+
+Continuing with the parser defined above, adding an
+:class:`OptionGroup` to a parser is easy::
+
+    group = OptionGroup(parser, "Dangerous Options",
+			"Caution: use these options at your own risk.  "
+			"It is believed that some of them bite.")
+    group.add_option("-g", action="store_true", help="Group option.")
+    parser.add_option_group(group)
+
+This would result in the following help output::
+
+    usage:  [options] arg1 arg2
+
+    options:
+      -h, --help           show this help message and exit
+      -v, --verbose        make lots of noise [default]
+      -q, --quiet          be vewwy quiet (I'm hunting wabbits)
+      -fFILE, --file=FILE  write output to FILE
+      -mMODE, --mode=MODE  interaction mode: one of 'novice', 'intermediate'
+			   [default], 'expert'
+
+      Dangerous Options:
+	Caution: use of these options is at your own risk.  It is believed that
+	some of them bite.
+	-g                 Group option.
 
 .. _optparse-printing-version-string:
 

File Doc/library/os.rst

       :func:`fdopen`, use its :meth:`close` method.
 
 
+.. function:: closerange(fd_low, fd_high)
+
+   Close all file descriptors from *fd_low* (inclusive) to *fd_high* (exclusive),
+   ignoring errors. Availability: Macintosh, Unix, Windows. Equivalent to::
+
+      for fd in xrange(fd_low, fd_high):
+          try:
+              os.close(fd)
+          except OSError:
+              pass
+
+   .. versionadded:: 2.6
+
+
 .. function:: device_encoding(fd)
 
    Return a string describing the encoding of the device associated with *fd*

File Doc/library/sqlite3.rst

-
 :mod:`sqlite3` --- DB-API 2.0 interface for SQLite databases
 ============================================================
 
 
 .. method:: Cursor.execute(sql, [parameters])
 
-   Executes a SQL statement. The SQL statement may be parametrized (i. e.
+   Executes an SQL statement. The SQL statement may be parametrized (i. e.
    placeholders instead of SQL literals). The :mod:`sqlite3` module supports two
    kinds of placeholders: question marks (qmark style) and named placeholders
    (named style).
 
 .. method:: Cursor.executemany(sql, seq_of_parameters)
 
-   Executes a SQL command against all parameter sequences or mappings found in
+   Executes an SQL command against all parameter sequences or mappings found in
    the sequence *sql*.  The :mod:`sqlite3` module also allows using an
    :term:`iterator` yielding parameters instead of a sequence.
 
    .. literalinclude:: ../includes/sqlite3/executescript.py
 
 
+.. method:: Cursor.fetchone() 
+          
+   Fetches the next row of a query result set, returning a single sequence,
+   or ``None`` when no more data is available.
+
+
+.. method:: Cursor.fetchmany([size=cursor.arraysize])
+          
+   Fetches the next set of rows of a query result, returning a list.  An empty
+   list is returned when no more rows are available.
+   
+   The number of rows to fetch per call is specified by the *size* parameter.
+   If it is not given, the cursor's arraysize determines the number of rows
+   to be fetched. The method should try to fetch as many rows as indicated by
+   the size parameter. If this is not possible due to the specified number of
+   rows not being available, fewer rows may be returned.
+   
+   Note there are performance considerations involved with the *size* parameter.
+   For optimal performance, it is usually best to use the arraysize attribute.
+   If the *size* parameter is used, then it is best for it to retain the same
+   value from one :meth:`fetchmany` call to the next.
+            
+.. method:: Cursor.fetchall() 
+
+   Fetches all (remaining) rows of a query result, returning a list.  Note that
+   the cursor's arraysize attribute can affect the performance of this operation.
+   An empty list is returned when no rows are available.
+
+
 .. attribute:: Cursor.rowcount
 
    Although the :class:`Cursor` class of the :mod:`sqlite3` module implements this

File Doc/library/xml.sax.utils.rst

 
    You can escape other strings of data by passing a dictionary as the optional
    *entities* parameter.  The keys and values must all be strings; each key will be
-   replaced with its corresponding value.
+   replaced with its corresponding value.  The characters ``'&'``, ``'<'`` and
+   ``'>'`` are always escaped, even if *entities* is provided.
 
 
 .. function:: unescape(data[, entities])
 
    You can unescape other strings of data by passing a dictionary as the optional
    *entities* parameter.  The keys and values must all be strings; each key will be
-   replaced with its corresponding value.
+   replaced with its corresponding value.  ``'&amp'``, ``'&lt;'``, and ``'&gt;'``
+   are always unescaped, even if *entities* is provided.
 
 
 .. function:: quoteattr(data[, entities])

File Doc/library/zipfile.rst

 documentation). It can handle ZIP files that use the ZIP64 extensions
 (that is ZIP files that are more than 4 GByte in size).  It supports
 decryption of encrypted files in ZIP archives, but it currently cannot
-create an encrypted file.
+create an encrypted file.  Decryption is extremely slow as it is
+implemented in native python rather than C.
 
 For other archive formats, see the :mod:`bz2`, :mod:`gzip`, and
 :mod:`tarfile` modules.

File Doc/whatsnew/2.6.rst

 
   .. Revision 57769
 
-
 * A new method in the :mod:`curses` module: for a window, :meth:`chgat` changes
   the display characters for a  certain number of characters on a single line.
+  (Contributed by Fabian Kreutz.)
   ::
 
      # Boldface text starting at y=0,x=21 
      # and affecting the rest of the line.
      stdscr.chgat(0,21, curses.A_BOLD)  
 
-  (Contributed by Fabian Kreutz.)
+  The :class:`Textbox` class in the :mod:`curses.textpad` module
+  now supports editing in insert mode as well as overwrite mode.
+  Insert mode is enabled by supplying a true value for the *insert_mode*
+  parameter when creating the :class:`Textbox` instance.
 
 * The :mod:`decimal` module was updated to version 1.66 of 
   `the General Decimal Specification <http://www2.hursley.ibm.com/decimal/decarith.html>`__.  New features

File Lib/curses/textpad.py

     KEY_LEFT = Ctrl-B, KEY_RIGHT = Ctrl-F, KEY_UP = Ctrl-P, KEY_DOWN = Ctrl-N
     KEY_BACKSPACE = Ctrl-h
     """
-    def __init__(self, win):
+    def __init__(self, win, insert_mode=False):
         self.win = win
+        self.insert_mode = insert_mode
         (self.maxy, self.maxx) = win.getmaxyx()
         self.maxy = self.maxy - 1
         self.maxx = self.maxx - 1
         win.keypad(1)
 
     def _end_of_line(self, y):