partial python wrapper implementation, see src/lib/dns/python/README for details

git-svn-id: svn://bind10.isc.org/svn/bind10/experiments/python-binding@1711 e5f2f494-b856-4b98-b285-d166d9295462

configure.ac

@@ -373,6 +373,7 @@ AC_CONFIG_FILES([Makefile
                  src/lib/config/tests/Makefile
                  src/lib/dns/Makefile
                  src/lib/dns/tests/Makefile
+                 src/lib/dns/python/Makefile
                  src/lib/dns-python/Makefile
                  src/lib/exceptions/Makefile
                  src/lib/auth/Makefile
@@ -409,6 +410,7 @@ AC_OUTPUT([src/bin/cfgmgr/b10-cfgmgr.py
            src/lib/config/tests/data_def_unittests_config.h
            src/lib/python/isc/config/tests/config_test
            src/lib/python/isc/cc/tests/cc_test
+           src/lib/dns/python/tests/libdns_python_test
            src/lib/dns/gen-rdatacode.py
            src/lib/dns/tests/testdata/gen-wiredata.py
           ], [
@@ -427,5 +429,6 @@ AC_OUTPUT([src/bin/cfgmgr/b10-cfgmgr.py
            chmod +x src/bin/msgq/msgq_test
            chmod +x src/lib/dns/gen-rdatacode.py
            chmod +x src/lib/dns/tests/testdata/gen-wiredata.py
+           chmod +x src/lib/dns/python/tests/libdns_python_test
           ])
 AC_OUTPUT

src/lib/dns/Makefile.am

-SUBDIRS = . tests
+SUBDIRS = . tests python
 
 AM_CPPFLAGS = -I$(top_srcdir)/src/lib -I$(top_builddir)/src/lib
 if GCC_WERROR_OK

src/lib/dns/python/Makefile.am

+AM_CPPFLAGS = -I$(top_srcdir)/src/lib -I$(top_builddir)/src/lib
+
+#lib_LTLIBRARIES = libdns_python_name.la libdns_python_rrset.la
+#libdns_python_name_la_SOURCES = name_python.cc
+#libdns_python_name_la_CPPFLAGS = $(AM_CPPFLAGS) $(PYTHON_INCLUDES)
+#libdns_python_name_la_LDFLAGS = $(PYTHON_LDFLAGS)
+
+#lib_LTLIBRARIES = libdns_python_name.la libdns_python_rrset.la
+lib_LTLIBRARIES = libdns_python.la
+libdns_python_la_SOURCES = libdns_python.cc libdns_python_common.cc
+libdns_python_la_CPPFLAGS = $(AM_CPPFLAGS) $(PYTHON_INCLUDES)
+libdns_python_la_LDFLAGS = $(PYTHON_LDFLAGS)
+
+#libdns_python_rrset_la_SOURCES = rrset_python.cc
+#libdns_python_rrset_la_CPPFLAGS = $(AM_CPPFLAGS) $(PYTHON_INCLUDES)
+#libdns_python_rrset_la_LDFLAGS = $(PYTHON_LDFLAGS) libdns_python_name.la
+
+#libdns_python_rrset_la_SOURCES = rrset_python.cc
+#libdns_python_rrset_la_CPPFLAGS = $(AM_CPPFLAGS) $(PYTHON_INCLUDES)
+#libdns_python_rrset_la_LDFLAGS = $(PYTHON_LDFLAGS)
+
+# Python prefers .so, while some OSes (specifically MacOS) use a different
+# suffix for dynamic objects.  -module is necessary to work this around.
+libdns_python_la_LDFLAGS += -module
+libdns_python_la_LIBADD = $(top_builddir)/src/lib/dns/libdns.la
+libdns_python_la_LIBADD += $(top_builddir)/src/lib/exceptions/libexceptions.la
+libdns_python_la_LIBADD += $(PYTHON_LIB)

src/lib/dns/python/README

+
+This is a partial implementation of the python wrappers for isc::dns.
+
+Currently, when compiled the module is called libdns_python. If we
+decide to use it we will add a default import under lib/python/isc.
+
+To use it from the source tree, you must add src/lib/dns/python/.libs
+to your PYTHONPATH environment variable. Within python you can then use
+> import libdns_python
+> rrc = libdns_python.RRClass("IN")
+
+Notes:
+
+this implementation is far from complete; currently wrappers for the
+following classes are implemented:
+
+full (though we might add some conveniences later, like __str__):
+RRType, RRClass, RRTTL, Name, and MessageRenderer
+
+partial:
+RRset (doesn't have a way to iterate over rdata yet)
+Rdata (only the most basic support, you can create one from a type,
+class and string, and you can convert them to text, but that's about
+it).
+
+We did not implement the buffer classes; everywhere in the API where
+buffers are used, you can pass a bytearray object.
+
+The 'main' module is defined in libdns_python.cc.
+There is a libdns_python_common.[cc|h] for helper functions.
+
+Implementation notes:
+
+Writing wrappers for a lot of classes is mostly a case of repetition.
+There are a lot of things one must do, and that is why nearly everyone
+immediately and continually has the urge to make generators for this.
+
+We have added a little more documentation than is strictly necessary to
+rrclass.h, for reference to new readers.
+
+To keep it maintainable as the original API changes, we use two
+techniques;
+
+1. Full unittests. Or at least as full as possible. All unittests from
+   the C++ code will also appear in the python wrapper tests (currently
+   only done for rrtype and rrset as far as implemented), so if we
+   forget to update a wrapper our tests should fail.
+2. Structure. I have tried to structure the wrapper files as much as
+   possible, see below.
+
+Structure:
+
+Since we are moving a lot of wrappers into one module, the specific
+classes are split over several files, each one having the name of the
+original header file they are wrapping (e.g. the wrapper for name.h
+becomes name_python.cc).
+
+At the top we first declare any exceptions, constants, and enums. These
+are all called po_<C++-name> (the actual python name will be set once
+they are added to the module in the module inialization function).
+
+Each class needs a struct that contains a pointer to an instance of the
+object (and any helper data). We call these structs s_<C++ class name>.
+
+Then we declare (but not define!) all methods we will export to
+python. These are named <C++ class name>_<C++ method name>.
+
+We will also need an _init and _destroy function for all of these.
+
+After the function declarations we define the method array; this
+contains the name of the methods as they appear in python, the wrapping
+function here, and documentation strings.
+
+Next is the type description; this is used for the wrapper code to
+convert native classes from and to python objects, and defines
+type-specific pointers (for instance to the method table mentioned above,
+but also to a __str__ function should one be defined, how the object
+should behave when it is used as a Sequence, etc.). For most classes,
+almost all values here shall be NULL.
+This has the name <lowercase C++ class name>_type.
+
+After that we define the exported functions we defined earlier. In some
+cases these need the type we just defined, and the type needed the
+function names, so for consistency, all functions are defined after,
+but declared before the type.
+
+This is repeated for every class we export.
+
+Finally we define the function to add the class, constants, exceptions,
+and enums to the module. This function is called from the init function
+in libdns_python.cc, has the name
+initModulePart_<c++ class name>, returns a boolean
+(true on success, false on failure), and takes the module as a
+PyObject*.

src/lib/dns/python/libdns_python.cc

+
+// Ok we want a lot of different parts of the DNS API in the python
+// module, but not one big 10000-line file.
+// So we split it up in several 'mini-modules'
+// These would be the same as a single module, except for
+// the init function, which has to be modified to a unique
+// name initModulePart_<name>, and return true/false instead of
+// NULL/*mod
+//
+// And of course care has to be taken that all identifiers be unique
+
+// 
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+
+#include "config.h"
+
+#include <exceptions/exceptions.h>
+
+#include <dns/buffer.h>
+#include <dns/exceptions.h>
+#include <dns/name.h>
+#include <dns/messagerenderer.h>
+
+#include "libdns_python_common.h"
+
+//#include "buffer_python.cc"
+// order is important here! (TODO: document dependencies)
+#include "name_python.cc"
+#include "messagerenderer_python.cc"
+#include "rrclass_python.cc"
+#include "rrtype_python.cc"
+#include "rrttl_python.cc"
+#include "rdata_python.cc"
+#include "rrset_python.cc"
+
+//
+// Definition of the module
+//
+static PyModuleDef libdns_python = {
+    { PyObject_HEAD_INIT(NULL) NULL, 0, NULL},
+    "libdns_python",
+    "Python bindings for isc.dns",
+    -1,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+PyMODINIT_FUNC
+PyInit_libdns_python(void)
+{
+    PyObject *mod = PyModule_Create(&libdns_python);
+    if (mod == NULL) {
+        return NULL;
+    }
+
+    // for each part included above, we call its specific initializer
+
+    if (!initModulePart_Name(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_MessageRenderer(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_RRClass(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_RRType(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_RRTTL(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_Rdata(mod)) {
+        return NULL;
+    }
+
+    if (!initModulePart_RRset(mod)) {
+        return NULL;
+    }
+
+    return mod;
+}
+

src/lib/dns/python/libdns_python_common.cc

+// Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// $Id$
+
+#include <Python.h>
+
+int
+readDataFromSequence(uint8_t *data, size_t len, PyObject* sequence)
+{
+    PyObject* el = NULL;
+    for (size_t i = 0; i < len; i++) {
+        el = PySequence_GetItem(sequence, 0);
+        if (!el) {
+            PyErr_SetString(PyExc_TypeError,
+                "sequence too short");
+            return -1;
+        }
+        if (PyLong_Check(el)) {
+            long l = PyLong_AsLong(el);
+            if (l < 0 || l > 255) {
+                PyErr_SetString(PyExc_TypeError,
+                    "number in fromWire sequence not between 0 and 255");
+                return -1;
+            }
+            data[i] = (uint8_t) PyLong_AsLong(el);
+            PySequence_DelItem(sequence, 0);
+        } else {
+            PyErr_SetString(PyExc_TypeError,
+                "not a number in fromWire sequence");
+            return -1;
+        }
+    }
+    return 0;
+}
+
+

src/lib/dns/python/libdns_python_common.h

+// Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// $Id$
+
+
+//
+// Shared functions for python/c API
+//
+
+// This function reads 'bytes' from a sequence
+// This sequence can be anything that implements the Sequence interface,
+// but must consist of Numbers between 0 and 255 for every value.
+//
+// The data is stored in *data.
+// Data must be allocated and have at least len bytes available.
+//
+// The current implementation removes read items from the
+// head of the sequence (even if it fails it removes everything that
+// it successfully read)
+int readDataFromSequence(uint8_t *data, size_t len, PyObject* sequence);

src/lib/dns/python/messagerenderer_python.cc

+// Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// $Id$
+
+#include <dns/messagerenderer.h>
+
+// For each class, we need a struct, a helper functions (init, destroy,
+// and static wrappers around the methods we export), a list of methods,
+// and a type description
+using namespace isc::dns;
+
+// MessageRenderer
+
+// since we don't use *Buffer in the python version (but work with
+// the already existing bytearray type where we use these custom buffers
+// in c++, we need to keep track of one here.
+typedef struct {
+    PyObject_HEAD
+    OutputBuffer* outputbuffer;
+    MessageRenderer* messagerenderer;
+} s_MessageRenderer;
+
+static int MessageRenderer_init(s_MessageRenderer* self);
+static void MessageRenderer_destroy(s_MessageRenderer* self);
+
+static PyObject* MessageRenderer_getData(s_MessageRenderer* self);
+static PyObject* MessageRenderer_getLength(s_MessageRenderer* self);
+static PyObject* MessageRenderer_isTruncated(s_MessageRenderer* self);
+static PyObject* MessageRenderer_getLengthLimit(s_MessageRenderer* self);
+
+static PyMethodDef MessageRenderer_methods[] = {
+    { "get_data", (PyCFunction)MessageRenderer_getData, METH_NOARGS, "Return the data" },
+    { "get_length", (PyCFunction)MessageRenderer_getLength, METH_NOARGS, "Return the length of the data" },
+    { "is_truncated", (PyCFunction)MessageRenderer_isTruncated, METH_NOARGS, "Returns True if the data is truncated" },
+    { "get_length_limit", (PyCFunction)MessageRenderer_getLengthLimit, METH_NOARGS, "Return the length limit of the data" },
+    { NULL, NULL, 0, NULL }
+};
+
+static PyTypeObject messagerenderer_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "libdns_python.MessageRenderer",
+    sizeof(s_MessageRenderer),                       /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    (destructor)MessageRenderer_destroy,   /* tp_dealloc */
+    NULL,                               /* tp_print */
+    NULL,                               /* tp_getattr */
+    NULL,                               /* tp_setattr */
+    NULL,                               /* tp_reserved */
+    NULL,                               /* tp_repr */
+    NULL,                               /* tp_as_number */
+    NULL,                               /* tp_as_sequence */
+    NULL,                               /* tp_as_mapping */
+    NULL,                               /* tp_hash  */
+    NULL,                               /* tp_call */
+    NULL,                               /* tp_str */
+    NULL,                               /* tp_getattro */
+    NULL,                               /* tp_setattro */
+    NULL,                               /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT,                 /* tp_flags */
+    "C++ MessageRenderer Object",  /* tp_doc */
+    NULL,                               /* tp_traverse */
+    NULL,                               /* tp_clear */
+    NULL,                               /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    NULL,                               /* tp_iter */
+    NULL,                               /* tp_iternext */
+    MessageRenderer_methods,                       /* tp_methods */
+    NULL,                               /* tp_members */
+    NULL,                               /* tp_getset */
+    NULL,                               /* tp_base */
+    NULL,                               /* tp_dict */
+    NULL,                               /* tp_descr_get */
+    NULL,                               /* tp_descr_set */
+    0,                                  /* tp_dictoffset */
+    (initproc)MessageRenderer_init,                /* tp_init */
+    NULL,                               /* tp_alloc */
+    PyType_GenericNew,                  /* tp_new */
+    NULL,                               /* tp_free */
+    NULL,                               /* tp_is_gc */
+    NULL,                               /* tp_bases */
+    NULL,                               /* tp_mro */
+    NULL,                               /* tp_cache */
+    NULL,                               /* tp_subclasses */
+    NULL,                               /* tp_weaklist */
+    // Note: not sure if the following are correct.  Added them just to
+    // make the compiler happy.
+    NULL,                               /* tp_del */
+    0                                   /* tp_version_tag */
+};
+
+static int
+MessageRenderer_init(s_MessageRenderer* self)
+{
+    self->outputbuffer = new OutputBuffer(4096);
+    self->messagerenderer = new MessageRenderer(*self->outputbuffer);
+    return 0;
+}
+
+static void
+MessageRenderer_destroy(s_MessageRenderer* self)
+{
+    delete self->messagerenderer;
+    delete self->outputbuffer;
+    self->messagerenderer = NULL;
+    Py_TYPE(self)->tp_free(self);
+}
+
+static PyObject*
+MessageRenderer_getData(s_MessageRenderer* self)
+{
+    return Py_BuildValue("y#", self->messagerenderer->getData(), self->messagerenderer->getLength());
+}
+
+static PyObject*
+MessageRenderer_getLength(s_MessageRenderer* self)
+{
+    return Py_BuildValue("I", self->messagerenderer->getLength());
+}
+
+static PyObject*
+MessageRenderer_isTruncated(s_MessageRenderer* self)
+{
+    if (self->messagerenderer->isTruncated())
+        Py_RETURN_TRUE;
+    else
+        Py_RETURN_FALSE;
+}
+
+static PyObject*
+MessageRenderer_getLengthLimit(s_MessageRenderer* self)
+{
+    return Py_BuildValue("I", self->messagerenderer->getLengthLimit());
+}
+
+// end of MessageRenderer
+
+
+// Module Initialization, all statics are initialized here
+bool
+initModulePart_MessageRenderer(PyObject* mod)
+{
+    // Add the exceptions to the module
+
+    // Add the enums to the module
+
+    // Add the constants to the module
+
+    // Add the classes to the module
+    // We initialize the static description object with PyType_Ready(),
+    // then add it to the module
+
+    // NameComparisonResult
+    if (PyType_Ready(&messagerenderer_type) < 0) {
+        return false;
+    }
+    Py_INCREF(&messagerenderer_type);
+    PyModule_AddObject(mod, "MessageRenderer",
+                       (PyObject*) &messagerenderer_type);
+    
+    return true;
+}
+
+

src/lib/dns/python/rdata_python.cc

+// Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// $Id$
+
+#include <dns/rdata.h>
+using namespace isc::dns;
+using namespace isc::dns::rdata;
+
+//
+// Declaration of the custom exceptions
+// Initialization and addition of these go in the initModulePart
+// function at the end of this file
+//
+static PyObject* po_InvalidRdataLength;
+static PyObject* po_InvalidRdataText;
+static PyObject* po_CharStringTooLong;
+
+//
+// Definition of the classes
+//
+
+// For each class, we need a struct, a helper functions (init, destroy,
+// and static wrappers around the methods we export), a list of methods,
+// and a type description
+
+//
+// Rdata
+//
+
+// The s_* Class simply coverst one instantiation of the object
+typedef struct {
+    PyObject_HEAD
+    RdataPtr rdata;
+} s_Rdata;
+
+//
+// We declare the functions here, the definitions are below
+// the type definition of the object, since both can use the other
+//
+
+// General creation and destruction
+static int Rdata_init(s_Rdata* self, PyObject* args);
+static void Rdata_destroy(s_Rdata* self);
+
+// These are the functions we export
+static PyObject* Rdata_toText(s_Rdata* self);
+// This is a second version of toText, we need one where the argument
+// is a PyObject*, for the str() function in python.
+static PyObject* Rdata_str(PyObject* self);
+static PyObject* Rdata_toWire(s_Rdata* self, PyObject* args);
+
+// This list contains the actual set of functions we have in
+// python. Each entry has
+// 1. Python method name
+// 2. Our static function here
+// 3. Argument type
+// 4. Documentation
+static PyMethodDef Rdata_methods[] = {
+    { "to_text", (PyCFunction)Rdata_toText, METH_NOARGS, "Return the string representation" },
+    { "to_wire", (PyCFunction)Rdata_toWire, METH_VARARGS, "wire format" },
+    { NULL, NULL, 0, NULL }
+};
+
+// This defines the complete type for reflection in python and
+// parsing of PyObject* to s_Rdata
+// Most of the functions are not actually implemented and NULL here.
+static PyTypeObject rdata_type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "libdns_python.Rdata",
+    sizeof(s_Rdata),                  /* tp_basicsize */
+    0,                                  /* tp_itemsize */
+    (destructor)Rdata_destroy,        /* tp_dealloc */
+    NULL,                               /* tp_print */
+    NULL,                               /* tp_getattr */
+    NULL,                               /* tp_setattr */
+    NULL,                               /* tp_reserved */
+    NULL,                               /* tp_repr */
+    NULL,                               /* tp_as_number */
+    NULL,                               /* tp_as_sequence */
+    NULL,                               /* tp_as_mapping */
+    NULL,                               /* tp_hash  */
+    NULL,                               /* tp_call */
+    Rdata_str,                               /* tp_str */
+    NULL,                               /* tp_getattro */
+    NULL,                               /* tp_setattro */
+    NULL,                               /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT,                 /* tp_flags */
+    "C++ Rdata Object",                 /* tp_doc */
+    NULL,                               /* tp_traverse */
+    NULL,                               /* tp_clear */
+    NULL,                               /* tp_richcompare */
+    0,                                  /* tp_weaklistoffset */
+    NULL,                               /* tp_iter */
+    NULL,                               /* tp_iternext */
+    Rdata_methods,                    /* tp_methods */
+    NULL,                               /* tp_members */
+    NULL,                               /* tp_getset */
+    NULL,                               /* tp_base */
+    NULL,                               /* tp_dict */