newtypes_tutorial.po

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# tomo, 2021
# Arihiro TAKASE, 2023
# 石井明久, 2024
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msgid ""
msgstr ""
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"Last-Translator: 石井明久, 2024\n"
"Language-Team: Japanese (https://app.transifex.com/python-doc/teams/5390/"
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#: ../../extending/newtypes_tutorial.rst:7
msgid "Defining Extension Types: Tutorial"
msgstr "拡張の型の定義: チュートリアル"

#: ../../extending/newtypes_tutorial.rst:14
msgid ""
"Python allows the writer of a C extension module to define new types that "
"can be manipulated from Python code, much like the built-in :class:`str` "
"and :class:`list` types.  The code for all extension types follows a "
"pattern, but there are some details that you need to understand before you "
"can get started.  This document is a gentle introduction to the topic."
msgstr ""
"Python では、組み込みの :class:`str` 型や :class:`list` 型のような Python "
"コードから操作できる新しい型を C 拡張モジュールの作者が定義できます。\n"
"全ての拡張の型のコードはあるパターンに従うのですが、書き始める前に理解してお"
"くべき細かいことがあります。\n"
"このドキュメントはその話題についてのやさしい入門です。"

#: ../../extending/newtypes_tutorial.rst:24
msgid "The Basics"
msgstr "基本的なこと"

#: ../../extending/newtypes_tutorial.rst:26
msgid ""
"The :term:`CPython` runtime sees all Python objects as variables of type :c:"
"expr:`PyObject*`, which serves as a \"base type\" for all Python objects. "
"The :c:type:`PyObject` structure itself only contains the object's :term:"
"`reference count` and a pointer to the object's \"type object\". This is "
"where the action is; the type object determines which (C) functions get "
"called by the interpreter when, for instance, an attribute gets looked up on "
"an object, a method called, or it is multiplied by another object.  These C "
"functions are called \"type methods\"."
msgstr ""
":term:`CPython` ランタイムは Python の全てのオブジェクトを、 Python の全ての"
"オブジェクトの \"基底型 (base type)\" である :c:expr:`PyObject*` 型の変数と見"
"なします。 :c:type:`PyObject` 構造体自身は :term:`参照カウント <reference "
"count>` と、オブジェクトの \"型オブジェクト\" へのポインタのみを持ちます。こ"
"こには動作が定義されています; 型オブジェクトは、例えば、ある属性があるオブ"
"ジェクトから検索されたり、メソッドが呼ばれたり、他のオブジェクトによって操作"
"されたりしたときに、どの (C) 関数がインタープリターから呼ばれるのかを決定しま"
"す。これらの C 関数は \"型メソッド (type method)\" と呼ばれます。"

#: ../../extending/newtypes_tutorial.rst:35
msgid ""
"So, if you want to define a new extension type, you need to create a new "
"type object."
msgstr ""
"それなので、新しい拡張の型を定義したいときは、新しい型オブジェクトを作成すれ"
"ばよいわけです。"

#: ../../extending/newtypes_tutorial.rst:38
msgid ""
"This sort of thing can only be explained by example, so here's a minimal, "
"but complete, module that defines a new type named :class:`!Custom` inside a "
"C extension module :mod:`!custom`:"
msgstr ""
"この手のことは例を見たほうが早いでしょうから、以下に C 拡張モジュール :mod:`!"
"custom` にある :class:`!Custom` という名前の新しい型を定義する、最小限ながら"
"完全なモジュールをあげておきます:"

#: ../../extending/newtypes_tutorial.rst:43
msgid ""
"What we're showing here is the traditional way of defining *static* "
"extension types.  It should be adequate for most uses.  The C API also "
"allows defining heap-allocated extension types using the :c:func:"
"`PyType_FromSpec` function, which isn't covered in this tutorial."
msgstr ""
"ここで紹介している例は、 *静的な* 拡張の型を定義する伝統的な実装方法です。\n"
"これはほとんどの場面で十分なものなのです。\n"
"C API では、 :c:func:`PyType_FromSpec` 関数を使い、ヒープ上に配置された拡張の"
"型も定義できますが、これについてはこのチュートリアルでは扱いません。"

#: ../../extending/newtypes_tutorial.rst:48
msgid ""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"\n"
"typedef struct {\n"
"    PyObject_HEAD\n"
"    /* Type-specific fields go here. */\n"
"} CustomObject;\n"
"\n"
"static PyTypeObject CustomType = {\n"
"    .ob_base = PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"custom.Custom\",\n"
"    .tp_doc = PyDoc_STR(\"Custom objects\"),\n"
"    .tp_basicsize = sizeof(CustomObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT,\n"
"    .tp_new = PyType_GenericNew,\n"
"};\n"
"\n"
"static PyModuleDef custommodule = {\n"
"    .m_base = PyModuleDef_HEAD_INIT,\n"
"    .m_name = \"custom\",\n"
"    .m_doc = \"Example module that creates an extension type.\",\n"
"    .m_size = -1,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_custom(void)\n"
"{\n"
"    PyObject *m;\n"
"    if (PyType_Ready(&CustomType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&custommodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"Custom\", (PyObject *) &CustomType) < 0) "
"{\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:50
msgid ""
"Now that's quite a bit to take in at once, but hopefully bits will seem "
"familiar from the previous chapter.  This file defines three things:"
msgstr ""
"一度に把握するにはちょっと量が多いですが、前の章よりはとっつきやすくなってい"
"ることと思います。このファイルでは、3つの要素が定義されています:"

#: ../../extending/newtypes_tutorial.rst:53
msgid ""
"What a :class:`!Custom` **object** contains: this is the ``CustomObject`` "
"struct, which is allocated once for each :class:`!Custom` instance."
msgstr ""
":class:`!Custom` **オブジェクト** が何を含んでいるか: これが "
"``CustomObject`` 構造体で、 :class:`!Custom` インスタンスごとに1回だけメモリ"
"確保が行われます。"

#: ../../extending/newtypes_tutorial.rst:55
msgid ""
"How the :class:`!Custom` **type** behaves: this is the ``CustomType`` "
"struct, which defines a set of flags and function pointers that the "
"interpreter inspects when specific operations are requested."
msgstr ""
":class:`!Custom` **型** がどのように振る舞うか: これが ``CustomType`` 構造体"
"で、フラグと関数ポインタの集まりを定義しています。特定の操作が要求されたとき"
"に、この関数ポインタをインタープリターが見に行きます。"

#: ../../extending/newtypes_tutorial.rst:58
msgid ""
"How to initialize the :mod:`!custom` module: this is the ``PyInit_custom`` "
"function and the associated ``custommodule`` struct."
msgstr ""
":mod:`!custom` モジュールをどう初期化するか: これが ``PyInit_custom`` 関数と"
"それに関係する ``custommodule`` 構造体です。"

#: ../../extending/newtypes_tutorial.rst:61
msgid "The first bit is::"
msgstr "まず最初はこれです::"

#: ../../extending/newtypes_tutorial.rst:63
msgid ""
"typedef struct {\n"
"    PyObject_HEAD\n"
"} CustomObject;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:67
msgid ""
"This is what a Custom object will contain.  ``PyObject_HEAD`` is mandatory "
"at the start of each object struct and defines a field called ``ob_base`` of "
"type :c:type:`PyObject`, containing a pointer to a type object and a "
"reference count (these can be accessed using the macros :c:macro:`Py_TYPE` "
"and :c:macro:`Py_REFCNT` respectively).  The reason for the macro is to "
"abstract away the layout and to enable additional fields in :ref:`debug "
"builds <debug-build>`."
msgstr ""
"これが Custom オブジェクトの内容です。 ``PyObject_HEAD`` はそれぞれのオブジェ"
"クト構造体の先頭に必須なもので、 :c:type:`PyObject` 型の ``ob_base`` という名"
"前のフィールドを定義します。 :c:type:`PyObject` 型には (それぞれ :c:macro:"
"`Py_TYPE` マクロおよび :c:macro:`Py_REFCNT` マクロからアクセスできる) 型オブ"
"ジェクトへのポインタと参照カウントが格納されています。このマクロが用意されて"
"いる理由は、構造体のレイアウトを抽象化し、デバッグビルドでフィールドを追加で"
"きるようにするためです。"

#: ../../extending/newtypes_tutorial.rst:76
msgid ""
"There is no semicolon above after the :c:macro:`PyObject_HEAD` macro. Be "
"wary of adding one by accident: some compilers will complain."
msgstr ""
"上の例では :c:macro:`PyObject_HEAD` マクロの後にセミコロンはありません。\n"
"うっかりセミコロンを追加しないように気を付けてください: これを警告するコンパ"
"イラもあります。"

#: ../../extending/newtypes_tutorial.rst:79
msgid ""
"Of course, objects generally store additional data besides the standard "
"``PyObject_HEAD`` boilerplate; for example, here is the definition for "
"standard Python floats::"
msgstr ""
"もちろん、一般的にはオブジェクトは標準的な ``PyObject_HEAD`` ボイラープレート"
"の他にもデータを保持しています; 例えば、これは Python 標準の浮動小数点数の定"
"義です::"

#: ../../extending/newtypes_tutorial.rst:83
msgid ""
"typedef struct {\n"
"    PyObject_HEAD\n"
"    double ob_fval;\n"
"} PyFloatObject;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:88
msgid "The second bit is the definition of the type object. ::"
msgstr "2つ目は型オブジェクトの定義です。 ::"

#: ../../extending/newtypes_tutorial.rst:90
msgid ""
"static PyTypeObject CustomType = {\n"
"    .ob_base = PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"custom.Custom\",\n"
"    .tp_doc = PyDoc_STR(\"Custom objects\"),\n"
"    .tp_basicsize = sizeof(CustomObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT,\n"
"    .tp_new = PyType_GenericNew,\n"
"};"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:101
msgid ""
"We recommend using C99-style designated initializers as above, to avoid "
"listing all the :c:type:`PyTypeObject` fields that you don't care about and "
"also to avoid caring about the fields' declaration order."
msgstr ""
"上にあるように C99 スタイルの指示付き初期化子を使って、 :c:type:"
"`PyTypeObject` の特に関心の無いフィールドまで全て並べたり、フィールドを宣言す"
"る順序に気を使ったりせずに済ませるのをお薦めします。"

#: ../../extending/newtypes_tutorial.rst:105
msgid ""
"The actual definition of :c:type:`PyTypeObject` in :file:`object.h` has many "
"more :ref:`fields <type-structs>` than the definition above.  The remaining "
"fields will be filled with zeros by the C compiler, and it's common practice "
"to not specify them explicitly unless you need them."
msgstr ""
":file:`object.h` にある実際の :c:type:`PyTypeObject` の定義には上の定義にある"
"よりももっと多くの :ref:`フィールド <type-structs>` があります。\n"
"ここに出てきていないフィールドは C コンパイラによってゼロで埋められるので、必"
"要でない限り明示的には値の指定をしないのが一般的な作法になっています。"

#: ../../extending/newtypes_tutorial.rst:110
msgid "We're going to pick it apart, one field at a time::"
msgstr "一度に1つずつフィールドを取り上げていきましょう::"

#: ../../extending/newtypes_tutorial.rst:112
msgid ".ob_base = PyVarObject_HEAD_INIT(NULL, 0)"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:114
msgid ""
"This line is mandatory boilerplate to initialize the ``ob_base`` field "
"mentioned above. ::"
msgstr ""
"この行は、上で触れた ``ob_base`` フィールドの初期化に必須のボイラープレートで"
"す。"

#: ../../extending/newtypes_tutorial.rst:117
msgid ".tp_name = \"custom.Custom\","
msgstr ""

#: ../../extending/newtypes_tutorial.rst:119
msgid ""
"The name of our type.  This will appear in the default textual "
"representation of our objects and in some error messages, for example:"
msgstr ""
"実装している型の名前です。\n"
"これは、オブジェクトのデフォルトの文字列表現やエラーメッセージに現れます。例"
"えば次の通りです:"

#: ../../extending/newtypes_tutorial.rst:122
msgid ""
">>> \"\" + custom.Custom()\n"
"Traceback (most recent call last):\n"
"  File \"<stdin>\", line 1, in <module>\n"
"TypeError: can only concatenate str (not \"custom.Custom\") to str"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:129
msgid ""
"Note that the name is a dotted name that includes both the module name and "
"the name of the type within the module. The module in this case is :mod:`!"
"custom` and the type is :class:`!Custom`, so we set the type name to :class:"
"`!custom.Custom`. Using the real dotted import path is important to make "
"your type compatible with the :mod:`pydoc` and :mod:`pickle` modules. ::"
msgstr ""
"型の名前が、モジュール名とモジュールにおける型の名前の両方をドットでつないだ"
"名前になっていることに注意してください。この場合は、モジュールは :mod:`!"
"custom` で型は :class:`!Custom` なので、型の名前を :class:`!custom.Custom` に"
"設定しました。実際のドット付きのインポートパスを使うのは、 :mod:`pydoc` モ"
"ジュールや :mod:`pickle` モジュールと互換性を持たせるために重要なのです。"

#: ../../extending/newtypes_tutorial.rst:135
msgid ""
".tp_basicsize = sizeof(CustomObject),\n"
".tp_itemsize = 0,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:138
msgid ""
"This is so that Python knows how much memory to allocate when creating new :"
"class:`!Custom` instances.  :c:member:`~PyTypeObject.tp_itemsize` is only "
"used for variable-sized objects and should otherwise be zero."
msgstr ""
"これは、新しい :class:`!Custom` インスタンスを作るときに Python が割り当てる"
"べきメモリがどのくらいなのかを知るためのものです。 :c:member:`~PyTypeObject."
"tp_itemsize` は可変サイズのオブジェクトでのみ使うものなので、サイズが可変でな"
"いオブジェクトでは 0 にすべきです。"

#: ../../extending/newtypes_tutorial.rst:144
msgid ""
"If you want your type to be subclassable from Python, and your type has the "
"same :c:member:`~PyTypeObject.tp_basicsize` as its base type, you may have "
"problems with multiple inheritance.  A Python subclass of your type will "
"have to list your type first in its :attr:`~type.__bases__`, or else it will "
"not be able to call your type's :meth:`~object.__new__` method without "
"getting an error.  You can avoid this problem by ensuring that your type has "
"a larger value for :c:member:`~PyTypeObject.tp_basicsize` than its base type "
"does.  Most of the time, this will be true anyway, because either your base "
"type will be :class:`object`, or else you will be adding data members to "
"your base type, and therefore increasing its size."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:154
msgid "We set the class flags to :c:macro:`Py_TPFLAGS_DEFAULT`. ::"
msgstr ":c:macro:`Py_TPFLAGS_DEFAULT` にクラスフラグを設定します。 ::"

#: ../../extending/newtypes_tutorial.rst:156
msgid ".tp_flags = Py_TPFLAGS_DEFAULT,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:158
msgid ""
"All types should include this constant in their flags.  It enables all of "
"the members defined until at least Python 3.3.  If you need further members, "
"you will need to OR the corresponding flags."
msgstr ""
"すべての型はフラグにこの定数を含めておく必要があります。これは最低でも "
"Python 3.3 までに定義されているすべてのメンバを許可します。それ以上のメンバが"
"必要なら、対応するフラグの OR をとる必要があります。"

#: ../../extending/newtypes_tutorial.rst:162
msgid ""
"We provide a doc string for the type in :c:member:`~PyTypeObject.tp_doc`. ::"
msgstr "この型の docstring は :c:member:`~PyTypeObject.tp_doc` に入れます。 ::"

#: ../../extending/newtypes_tutorial.rst:164
msgid ".tp_doc = PyDoc_STR(\"Custom objects\"),"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:166
msgid ""
"To enable object creation, we have to provide a :c:member:`~PyTypeObject."
"tp_new` handler.  This is the equivalent of the Python method :meth:`~object."
"__new__`, but has to be specified explicitly.  In this case, we can just use "
"the default implementation provided by the API function :c:func:"
"`PyType_GenericNew`. ::"
msgstr ""
"オブジェクトが生成できるように、 :c:member:`~PyTypeObject.tp_new` ハンドラを"
"提供する必要があります。これは Python のメソッド :meth:`~object.__new__` と同"
"等のものですが、明示的に与える必要があります。今の場合では、 API 関数の :c:"
"func:`PyType_GenericNew` として提供されるデフォルトの実装をそのまま使えま"
"す。 ::"

#: ../../extending/newtypes_tutorial.rst:171
msgid ".tp_new = PyType_GenericNew,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:173
msgid ""
"Everything else in the file should be familiar, except for some code in :c:"
"func:`!PyInit_custom`::"
msgstr ""
"ファイルの残りの部分はきっと馴染みやすいものだと思いますが、 :c:func:`!"
"PyInit_custom` の一部のコードはそうではないでしょう::"

#: ../../extending/newtypes_tutorial.rst:176
msgid ""
"if (PyType_Ready(&CustomType) < 0)\n"
"    return;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:179
msgid ""
"This initializes the :class:`!Custom` type, filling in a number of members "
"to the appropriate default values, including :c:member:`~PyObject.ob_type` "
"that we initially set to ``NULL``. ::"
msgstr ""
"これは、 ``NULL`` に初期化された :c:member:`~PyObject.ob_type` も含めて、いく"
"つかのメンバーを適切なデフォルト値で埋めて、 :class:`!Custom` 型を初期化しま"
"す。 ::"

#: ../../extending/newtypes_tutorial.rst:183
msgid ""
"if (PyModule_AddObjectRef(m, \"Custom\", (PyObject *) &CustomType) < 0) {\n"
"    Py_DECREF(m);\n"
"    return NULL;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:188
msgid ""
"This adds the type to the module dictionary.  This allows us to create :"
"class:`!Custom` instances by calling the :class:`!Custom` class:"
msgstr ""
"これは型をモジュールの辞書に追加します。こうすることで :class:`!Custom` クラ"
"スの呼び出しで :class:`!Custom` インスタンスが作成できるようになります:"

#: ../../extending/newtypes_tutorial.rst:191
msgid ""
">>> import custom\n"
">>> mycustom = custom.Custom()"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:196
msgid ""
"That's it!  All that remains is to build it; put the above code in a file "
"called :file:`custom.c`,"
msgstr ""
"以上です!残りの作業はビルドだけです; :file:`custom.c` という名前のファイルに"
"ここまでのコードを書き込み、"

#: ../../extending/newtypes_tutorial.rst:199
msgid ""
"[build-system]\n"
"requires = [\"setuptools\"]\n"
"build-backend = \"setuptools.build_meta\"\n"
"\n"
"[project]\n"
"name = \"custom\"\n"
"version = \"1\"\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:201
msgid "in a file called :file:`pyproject.toml`, and"
msgstr ":file:`pyproject.toml` というファイルにこれを書き込み、"

#: ../../extending/newtypes_tutorial.rst:203
msgid ""
"from setuptools import Extension, setup\n"
"setup(ext_modules=[Extension(\"custom\", [\"custom.c\"])])"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:208
msgid "in a file called :file:`setup.py`; then typing"
msgstr ""
"そして :file:`setup.py` というファイルにこのように書き込み、そして、以下のよ"
"うに"

#: ../../extending/newtypes_tutorial.rst:210
#: ../../extending/newtypes_tutorial.rst:525
msgid "$ python -m pip install ."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:214
msgid ""
"in a shell should produce a file :file:`custom.so` in a subdirectory and "
"install it; now fire up Python --- you should be able to ``import custom`` "
"and play around with ``Custom`` objects."
msgstr ""
"シェルに入力します。これにより、サブディレクトリに :file:`custom.so` が生成さ"
"れ、インストールされます。これで、 Python を立ち上げて、 ``import custom`` す"
"ると ``Custom`` オブジェクトで遊べるようになっているはずです。"

#: ../../extending/newtypes_tutorial.rst:218
msgid "That wasn't so hard, was it?"
msgstr "そんなにむずかしくありません、よね?"

#: ../../extending/newtypes_tutorial.rst:220
msgid ""
"Of course, the current Custom type is pretty uninteresting. It has no data "
"and doesn't do anything. It can't even be subclassed."
msgstr ""
"もちろん、現在の Custom 型は面白みに欠けています。何もデータを持っていない"
"し、何もできません。継承してサブクラスを作ることさえできないのです。"

#: ../../extending/newtypes_tutorial.rst:225
msgid "Adding data and methods to the Basic example"
msgstr "基本のサンプルにデータとメソッドを追加する"

#: ../../extending/newtypes_tutorial.rst:227
msgid ""
"Let's extend the basic example to add some data and methods.  Let's also "
"make the type usable as a base class. We'll create a new module, :mod:`!"
"custom2` that adds these capabilities:"
msgstr ""
"この基本のサンプルにデータとメソッドを追加してみましょう。ついでに、この型を"
"基底クラスとしても利用できるようにします。ここでは新しいモジュール :mod:`!"
"custom2` をつくり、これらの機能を追加します:"

#: ../../extending/newtypes_tutorial.rst:231
msgid ""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"#include <stddef.h> /* for offsetof() */\n"
"\n"
"typedef struct {\n"
"    PyObject_HEAD\n"
"    PyObject *first; /* first name */\n"
"    PyObject *last;  /* last name */\n"
"    int number;\n"
"} CustomObject;\n"
"\n"
"static void\n"
"Custom_dealloc(CustomObject *self)\n"
"{\n"
"    Py_XDECREF(self->first);\n"
"    Py_XDECREF(self->last);\n"
"    Py_TYPE(self)->tp_free((PyObject *) self);\n"
"}\n"
"\n"
"static PyObject *\n"
"Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)\n"
"{\n"
"    CustomObject *self;\n"
"    self = (CustomObject *) type->tp_alloc(type, 0);\n"
"    if (self != NULL) {\n"
"        self->first = PyUnicode_FromString(\"\");\n"
"        if (self->first == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->last = PyUnicode_FromString(\"\");\n"
"        if (self->last == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->number = 0;\n"
"    }\n"
"    return (PyObject *) self;\n"
"}\n"
"\n"
"static int\n"
"Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    static char *kwlist[] = {\"first\", \"last\", \"number\", NULL};\n"
"    PyObject *first = NULL, *last = NULL;\n"
"\n"
"    if (!PyArg_ParseTupleAndKeywords(args, kwds, \"|OOi\", kwlist,\n"
"                                     &first, &last,\n"
"                                     &self->number))\n"
"        return -1;\n"
"\n"
"    if (first) {\n"
"        Py_XSETREF(self->first, Py_NewRef(first));\n"
"    }\n"
"    if (last) {\n"
"        Py_XSETREF(self->last, Py_NewRef(last));\n"
"    }\n"
"    return 0;\n"
"}\n"
"\n"
"static PyMemberDef Custom_members[] = {\n"
"    {\"first\", Py_T_OBJECT_EX, offsetof(CustomObject, first), 0,\n"
"     \"first name\"},\n"
"    {\"last\", Py_T_OBJECT_EX, offsetof(CustomObject, last), 0,\n"
"     \"last name\"},\n"
"    {\"number\", Py_T_INT, offsetof(CustomObject, number), 0,\n"
"     \"custom number\"},\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyObject *\n"
"Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))\n"
"{\n"
"    if (self->first == NULL) {\n"
"        PyErr_SetString(PyExc_AttributeError, \"first\");\n"
"        return NULL;\n"
"    }\n"
"    if (self->last == NULL) {\n"
"        PyErr_SetString(PyExc_AttributeError, \"last\");\n"
"        return NULL;\n"
"    }\n"
"    return PyUnicode_FromFormat(\"%S %S\", self->first, self->last);\n"
"}\n"
"\n"
"static PyMethodDef Custom_methods[] = {\n"
"    {\"name\", (PyCFunction) Custom_name, METH_NOARGS,\n"
"     \"Return the name, combining the first and last name\"\n"
"    },\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyTypeObject CustomType = {\n"
"    .ob_base = PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"custom2.Custom\",\n"
"    .tp_doc = PyDoc_STR(\"Custom objects\"),\n"
"    .tp_basicsize = sizeof(CustomObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,\n"
"    .tp_new = Custom_new,\n"
"    .tp_init = (initproc) Custom_init,\n"
"    .tp_dealloc = (destructor) Custom_dealloc,\n"
"    .tp_members = Custom_members,\n"
"    .tp_methods = Custom_methods,\n"
"};\n"
"\n"
"static PyModuleDef custommodule = {\n"
"    .m_base =PyModuleDef_HEAD_INIT,\n"
"    .m_name = \"custom2\",\n"
"    .m_doc = \"Example module that creates an extension type.\",\n"
"    .m_size = -1,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_custom2(void)\n"
"{\n"
"    PyObject *m;\n"
"    if (PyType_Ready(&CustomType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&custommodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"Custom\", (PyObject *) &CustomType) < 0) "
"{\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:234
msgid "This version of the module has a number of changes."
msgstr "モジュールのこのバージョンでは、いくつもの変更をおこないます。"

#: ../../extending/newtypes_tutorial.rst:236
msgid ""
"The  :class:`!Custom` type now has three data attributes in its C struct, "
"*first*, *last*, and *number*.  The *first* and *last* variables are Python "
"strings containing first and last names.  The *number* attribute is a C "
"integer."
msgstr ""
":class:`!Custom` 型は そのC構造体に 3つのデータ属性 *first* 、 *last* 、およ"
"び *number* をもつようになりました。 *first* と *last* 属性はファーストネーム"
"とラストネームを格納した Python 文字列で、 *number* 属性は C言語での整数の値"
"です。"

#: ../../extending/newtypes_tutorial.rst:240
msgid "The object structure is updated accordingly::"
msgstr "これにしたがうと、オブジェクトの構造体は次のようになります::"

#: ../../extending/newtypes_tutorial.rst:242
msgid ""
"typedef struct {\n"
"    PyObject_HEAD\n"
"    PyObject *first; /* first name */\n"
"    PyObject *last;  /* last name */\n"
"    int number;\n"
"} CustomObject;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:249
msgid ""
"Because we now have data to manage, we have to be more careful about object "
"allocation and deallocation.  At a minimum, we need a deallocation method::"
msgstr ""
"いまや管理すべきデータができたので、オブジェクトの割り当てと解放に際してはよ"
"り慎重になる必要があります。最低限、オブジェクトの解放メソッドが必要です::"

#: ../../extending/newtypes_tutorial.rst:252
msgid ""
"static void\n"
"Custom_dealloc(CustomObject *self)\n"
"{\n"
"    Py_XDECREF(self->first);\n"
"    Py_XDECREF(self->last);\n"
"    Py_TYPE(self)->tp_free((PyObject *) self);\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:260
msgid "which is assigned to the :c:member:`~PyTypeObject.tp_dealloc` member::"
msgstr ""
"この関数は :c:member:`~PyTypeObject.tp_dealloc` メンバに代入されます。 ::"

#: ../../extending/newtypes_tutorial.rst:262
msgid ".tp_dealloc = (destructor) Custom_dealloc,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:264
msgid ""
"This method first clears the reference counts of the two Python attributes. :"
"c:func:`Py_XDECREF` correctly handles the case where its argument is "
"``NULL`` (which might happen here if ``tp_new`` failed midway).  It then "
"calls the :c:member:`~PyTypeObject.tp_free` member of the object's type "
"(computed by ``Py_TYPE(self)``) to free the object's memory.  Note that the "
"object's type might not be :class:`!CustomType`, because the object may be "
"an instance of a subclass."
msgstr ""
"このメソッドは、まず二つのPython 属性の参照カウントをクリアします。 :c:func:"
"`Py_XDECREF` は引数が ``NULL`` のケースを正しく扱えます (これは、``tp_new`` "
"が途中で失敗した場合に起こりえます) 。このメソッドは、つぎにオブジェクトの型 "
"(``Py_TYPE(self)`` で算出します) のメンバ :c:member:`~PyTypeObject.tp_free` "
"を呼び出し、オブジェクトのメモリを開放します。オブジェクトの型が :class:`!"
"CustomType` であるとは限らない点に注意してください。なぜなら、オブジェクトは"
"サブクラスのインスタンスかもしれないからです。"

#: ../../extending/newtypes_tutorial.rst:273
msgid ""
"The explicit cast to ``destructor`` above is needed because we defined "
"``Custom_dealloc`` to take a ``CustomObject *`` argument, but the "
"``tp_dealloc`` function pointer expects to receive a ``PyObject *`` "
"argument.  Otherwise, the compiler will emit a warning.  This is object-"
"oriented polymorphism, in C!"
msgstr ""
"上の ``destructor`` への明示的な型変換は必要です。なぜなら、 "
"``Custom_dealloc`` が ``CustomObject *`` 引数をとると定義しましたが、 "
"``tp_dealloc`` 関数のポインタは ``PyObject *`` 引数を受け取ることになっている"
"からです。もし明示的に型変換をしなければ、コンパイラが警告を発するでしょう。"
"これは、 C におけるオブジェクト指向のポリモーフィズムです！"

#: ../../extending/newtypes_tutorial.rst:279
msgid ""
"We want to make sure that the first and last names are initialized to empty "
"strings, so we provide a ``tp_new`` implementation::"
msgstr ""
"ファーストネームとラストネームを空文字列に初期化しておきたいので、``tp_new`` "
"の実装を追加することにしましょう::"

#: ../../extending/newtypes_tutorial.rst:282
msgid ""
"static PyObject *\n"
"Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)\n"
"{\n"
"    CustomObject *self;\n"
"    self = (CustomObject *) type->tp_alloc(type, 0);\n"
"    if (self != NULL) {\n"
"        self->first = PyUnicode_FromString(\"\");\n"
"        if (self->first == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->last = PyUnicode_FromString(\"\");\n"
"        if (self->last == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->number = 0;\n"
"    }\n"
"    return (PyObject *) self;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:303
msgid "and install it in the :c:member:`~PyTypeObject.tp_new` member::"
msgstr ""
"そしてこれを :c:member:`~PyTypeObject.tp_new` メンバとしてインストールしま"
"す::"

#: ../../extending/newtypes_tutorial.rst:305
msgid ".tp_new = Custom_new,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:307
msgid ""
"The ``tp_new`` handler is responsible for creating (as opposed to "
"initializing) objects of the type.  It is exposed in Python as the :meth:"
"`~object.__new__` method. It is not required to define a ``tp_new`` member, "
"and indeed many extension types will simply reuse :c:func:"
"`PyType_GenericNew` as done in the first version of the :class:`!Custom` "
"type above.  In this case, we use the ``tp_new`` handler to initialize the "
"``first`` and ``last`` attributes to non-``NULL`` default values."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:315
msgid ""
"``tp_new`` is passed the type being instantiated (not necessarily "
"``CustomType``, if a subclass is instantiated) and any arguments passed when "
"the type was called, and is expected to return the instance created.  "
"``tp_new`` handlers always accept positional and keyword arguments, but they "
"often ignore the arguments, leaving the argument handling to initializer (a."
"k.a. ``tp_init`` in C or ``__init__`` in Python) methods."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:323
msgid ""
"``tp_new`` shouldn't call ``tp_init`` explicitly, as the interpreter will do "
"it itself."
msgstr ""
"``tp_new`` は明示的に ``tp_init`` を呼び出してはいけません、これはインタープ"
"リタが自分で行うためです。"

#: ../../extending/newtypes_tutorial.rst:326
msgid ""
"The ``tp_new`` implementation calls the :c:member:`~PyTypeObject.tp_alloc` "
"slot to allocate memory::"
msgstr ""
"この ``tp_new`` の実装は、:c:member:`~PyTypeObject.tp_alloc` スロットを呼び出"
"してメモリを割り当てます::"

#: ../../extending/newtypes_tutorial.rst:329
msgid "self = (CustomObject *) type->tp_alloc(type, 0);"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:331
msgid ""
"Since memory allocation may fail, we must check the :c:member:`~PyTypeObject."
"tp_alloc` result against ``NULL`` before proceeding."
msgstr ""
"メモリ割り当ては失敗するかもしれないので、先に進む前に :c:member:"
"`~PyTypeObject.tp_alloc` の結果が ``NULL`` でないかチェックしなければなりませ"
"ん。"

#: ../../extending/newtypes_tutorial.rst:335
msgid ""
"We didn't fill the :c:member:`~PyTypeObject.tp_alloc` slot ourselves. "
"Rather :c:func:`PyType_Ready` fills it for us by inheriting it from our base "
"class, which is :class:`object` by default.  Most types use the default "
"allocation strategy."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:341
msgid ""
"If you are creating a co-operative :c:member:`~PyTypeObject.tp_new` (one "
"that calls a base type's :c:member:`~PyTypeObject.tp_new` or :meth:`~object."
"__new__`), you must *not* try to determine what method to call using method "
"resolution order at runtime.  Always statically determine what type you are "
"going to call, and call its :c:member:`~PyTypeObject.tp_new` directly, or "
"via ``type->tp_base->tp_new``.  If you do not do this, Python subclasses of "
"your type that also inherit from other Python-defined classes may not work "
"correctly. (Specifically, you may not be able to create instances of such "
"subclasses without getting a :exc:`TypeError`.)"
msgstr ""
"もし協力的な :c:member:`~PyTypeObject.tp_new` (基底タイプの :c:member:"
"`~PyTypeObject.tp_new` または :meth:`~object.__new__` を呼んでいるもの) を作"
"りたいのならば、実行時のメソッド解決順序をつかってどのメソッドを呼びだすかを"
"決定しようとしては *いけません* 。常に呼び出す型を静的に決めておき、直接そ"
"の :c:member:`~PyTypeObject.tp_new` を呼び出すか、あるいは ``type->tp_base-"
">tp_new`` を経由してください。こうしないと、あなたが作成したタイプの Python "
"サブクラスが他の Python で定義されたクラスも継承している場合にうまく動かない"
"場合があります。 (とりわけ、そのようなサブクラスのインスタンスを :exc:"
"`TypeError` を出さずに作ることが不可能になります。)"

#: ../../extending/newtypes_tutorial.rst:351
msgid ""
"We also define an initialization function which accepts arguments to provide "
"initial values for our instance::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:354
msgid ""
"static int\n"
"Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    static char *kwlist[] = {\"first\", \"last\", \"number\", NULL};\n"
"    PyObject *first = NULL, *last = NULL, *tmp;\n"
"\n"
"    if (!PyArg_ParseTupleAndKeywords(args, kwds, \"|OOi\", kwlist,\n"
"                                     &first, &last,\n"
"                                     &self->number))\n"
"        return -1;\n"
"\n"
"    if (first) {\n"
"        tmp = self->first;\n"
"        Py_INCREF(first);\n"
"        self->first = first;\n"
"        Py_XDECREF(tmp);\n"
"    }\n"
"    if (last) {\n"
"        tmp = self->last;\n"
"        Py_INCREF(last);\n"
"        self->last = last;\n"
"        Py_XDECREF(tmp);\n"
"    }\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:380
msgid "by filling the :c:member:`~PyTypeObject.tp_init` slot. ::"
msgstr "これは :c:member:`~PyTypeObject.tp_init` メンバに代入されます。 ::"

#: ../../extending/newtypes_tutorial.rst:382
msgid ".tp_init = (initproc) Custom_init,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:384
msgid ""
"The :c:member:`~PyTypeObject.tp_init` slot is exposed in Python as the :meth:"
"`~object.__init__` method.  It is used to initialize an object after it's "
"created.  Initializers always accept positional and keyword arguments, and "
"they should return either ``0`` on success or ``-1`` on error."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:389
msgid ""
"Unlike the ``tp_new`` handler, there is no guarantee that ``tp_init`` is "
"called at all (for example, the :mod:`pickle` module by default doesn't "
"call :meth:`~object.__init__` on unpickled instances).  It can also be "
"called multiple times.  Anyone can call the :meth:`!__init__` method on our "
"objects.  For this reason, we have to be extra careful when assigning the "
"new attribute values.  We might be tempted, for example to assign the "
"``first`` member like this::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:397
msgid ""
"if (first) {\n"
"    Py_XDECREF(self->first);\n"
"    Py_INCREF(first);\n"
"    self->first = first;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:403
msgid ""
"But this would be risky.  Our type doesn't restrict the type of the "
"``first`` member, so it could be any kind of object.  It could have a "
"destructor that causes code to be executed that tries to access the "
"``first`` member; or that destructor could release the :term:`Global "
"interpreter Lock <GIL>` and let arbitrary code run in other threads that "
"accesses and modifies our object."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:410
msgid ""
"To be paranoid and protect ourselves against this possibility, we almost "
"always reassign members before decrementing their reference counts.  When "
"don't we have to do this?"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:414
msgid "when we absolutely know that the reference count is greater than 1;"
msgstr "その参照カウントが 1 より大きいと確信できる場合"

#: ../../extending/newtypes_tutorial.rst:416
msgid ""
"when we know that deallocation of the object [#]_ will neither release the :"
"term:`GIL` nor cause any calls back into our type's code;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:419
msgid ""
"when decrementing a reference count in a :c:member:`~PyTypeObject."
"tp_dealloc` handler on a type which doesn't support cyclic garbage "
"collection [#]_."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:422
msgid ""
"We want to expose our instance variables as attributes. There are a number "
"of ways to do that. The simplest way is to define member definitions::"
msgstr ""
"ここではインスタンス変数を属性として見えるようにしたいのですが、これにはいく"
"つもの方法があります。もっとも簡単な方法は、メンバの定義を与えることです::"

#: ../../extending/newtypes_tutorial.rst:425
msgid ""
"static PyMemberDef Custom_members[] = {\n"
"    {\"first\", Py_T_OBJECT_EX, offsetof(CustomObject, first), 0,\n"
"     \"first name\"},\n"
"    {\"last\", Py_T_OBJECT_EX, offsetof(CustomObject, last), 0,\n"
"     \"last name\"},\n"
"    {\"number\", Py_T_INT, offsetof(CustomObject, number), 0,\n"
"     \"custom number\"},\n"
"    {NULL}  /* Sentinel */\n"
"};"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:435
msgid ""
"and put the definitions in the :c:member:`~PyTypeObject.tp_members` slot::"
msgstr ""
"そして、この定義を :c:member:`~PyTypeObject.tp_members` スロットに入れましょ"
"う::"

#: ../../extending/newtypes_tutorial.rst:437
msgid ".tp_members = Custom_members,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:439
msgid ""
"Each member definition has a member name, type, offset, access flags and "
"documentation string.  See the :ref:`Generic-Attribute-Management` section "
"below for details."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:443
msgid ""
"A disadvantage of this approach is that it doesn't provide a way to restrict "
"the types of objects that can be assigned to the Python attributes.  We "
"expect the first and last names to be strings, but any Python objects can be "
"assigned. Further, the attributes can be deleted, setting the C pointers to "
"``NULL``.  Even though we can make sure the members are initialized to non-"
"``NULL`` values, the members can be set to ``NULL`` if the attributes are "
"deleted."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:450
msgid ""
"We define a single method, :meth:`!Custom.name`, that outputs the objects "
"name as the concatenation of the first and last names. ::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:453
msgid ""
"static PyObject *\n"
"Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))\n"
"{\n"
"    if (self->first == NULL) {\n"
"        PyErr_SetString(PyExc_AttributeError, \"first\");\n"
"        return NULL;\n"
"    }\n"
"    if (self->last == NULL) {\n"
"        PyErr_SetString(PyExc_AttributeError, \"last\");\n"
"        return NULL;\n"
"    }\n"
"    return PyUnicode_FromFormat(\"%S %S\", self->first, self->last);\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:467
msgid ""
"The method is implemented as a C function that takes a :class:`!Custom` (or :"
"class:`!Custom` subclass) instance as the first argument.  Methods always "
"take an instance as the first argument. Methods often take positional and "
"keyword arguments as well, but in this case we don't take any and don't need "
"to accept a positional argument tuple or keyword argument dictionary. This "
"method is equivalent to the Python method:"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:474
msgid ""
"def name(self):\n"
"    return \"%s %s\" % (self.first, self.last)"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:479
msgid ""
"Note that we have to check for the possibility that our :attr:`!first` and :"
"attr:`!last` members are ``NULL``.  This is because they can be deleted, in "
"which case they are set to ``NULL``.  It would be better to prevent deletion "
"of these attributes and to restrict the attribute values to be strings.  "
"We'll see how to do that in the next section."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:485
msgid ""
"Now that we've defined the method, we need to create an array of method "
"definitions::"
msgstr ""
"さて、メソッドを定義したので、ここでメソッド定義用の配列を作成する必要があり"
"ます::"

#: ../../extending/newtypes_tutorial.rst:488
msgid ""
"static PyMethodDef Custom_methods[] = {\n"
"    {\"name\", (PyCFunction) Custom_name, METH_NOARGS,\n"
"     \"Return the name, combining the first and last name\"\n"
"    },\n"
"    {NULL}  /* Sentinel */\n"
"};"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:495
msgid ""
"(note that we used the :c:macro:`METH_NOARGS` flag to indicate that the "
"method is expecting no arguments other than *self*)"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:498
msgid "and assign it to the :c:member:`~PyTypeObject.tp_methods` slot::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:500
msgid ".tp_methods = Custom_methods,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:502
msgid ""
"Finally, we'll make our type usable as a base class for subclassing.  We've "
"written our methods carefully so far so that they don't make any assumptions "
"about the type of the object being created or used, so all we need to do is "
"to add the :c:macro:`Py_TPFLAGS_BASETYPE` to our class flag definition::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:507
msgid ".tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:509
msgid ""
"We rename :c:func:`!PyInit_custom` to :c:func:`!PyInit_custom2`, update the "
"module name in the :c:type:`PyModuleDef` struct, and update the full class "
"name in the :c:type:`PyTypeObject` struct."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:513
msgid "Finally, we update our :file:`setup.py` file to include the new module,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:515
msgid ""
"from setuptools import Extension, setup\n"
"setup(ext_modules=[\n"
"    Extension(\"custom\", [\"custom.c\"]),\n"
"    Extension(\"custom2\", [\"custom2.c\"]),\n"
"])"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:523
msgid "and then we re-install so that we can ``import custom2``:"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:530
msgid "Providing finer control over data attributes"
msgstr "データ属性をこまかく制御する"

#: ../../extending/newtypes_tutorial.rst:532
msgid ""
"In this section, we'll provide finer control over how the :attr:`!first` "
"and :attr:`!last` attributes are set in the :class:`!Custom` example. In the "
"previous version of our module, the instance variables :attr:`!first` and :"
"attr:`!last` could be set to non-string values or even deleted. We want to "
"make sure that these attributes always contain strings."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:538
msgid ""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"#include <stddef.h> /* for offsetof() */\n"
"\n"
"typedef struct {\n"
"    PyObject_HEAD\n"
"    PyObject *first; /* first name */\n"
"    PyObject *last;  /* last name */\n"
"    int number;\n"
"} CustomObject;\n"
"\n"
"static void\n"
"Custom_dealloc(CustomObject *self)\n"
"{\n"
"    Py_XDECREF(self->first);\n"
"    Py_XDECREF(self->last);\n"
"    Py_TYPE(self)->tp_free((PyObject *) self);\n"
"}\n"
"\n"
"static PyObject *\n"
"Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)\n"
"{\n"
"    CustomObject *self;\n"
"    self = (CustomObject *) type->tp_alloc(type, 0);\n"
"    if (self != NULL) {\n"
"        self->first = PyUnicode_FromString(\"\");\n"
"        if (self->first == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->last = PyUnicode_FromString(\"\");\n"
"        if (self->last == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->number = 0;\n"
"    }\n"
"    return (PyObject *) self;\n"
"}\n"
"\n"
"static int\n"
"Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    static char *kwlist[] = {\"first\", \"last\", \"number\", NULL};\n"
"    PyObject *first = NULL, *last = NULL;\n"
"\n"
"    if (!PyArg_ParseTupleAndKeywords(args, kwds, \"|UUi\", kwlist,\n"
"                                     &first, &last,\n"
"                                     &self->number))\n"
"        return -1;\n"
"\n"
"    if (first) {\n"
"        Py_SETREF(self->first, Py_NewRef(first));\n"
"    }\n"
"    if (last) {\n"
"        Py_SETREF(self->last, Py_NewRef(last));\n"
"    }\n"
"    return 0;\n"
"}\n"
"\n"
"static PyMemberDef Custom_members[] = {\n"
"    {\"number\", Py_T_INT, offsetof(CustomObject, number), 0,\n"
"     \"custom number\"},\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyObject *\n"
"Custom_getfirst(CustomObject *self, void *closure)\n"
"{\n"
"    return Py_NewRef(self->first);\n"
"}\n"
"\n"
"static int\n"
"Custom_setfirst(CustomObject *self, PyObject *value, void *closure)\n"
"{\n"
"    if (value == NULL) {\n"
"        PyErr_SetString(PyExc_TypeError, \"Cannot delete the first "
"attribute\");\n"
"        return -1;\n"
"    }\n"
"    if (!PyUnicode_Check(value)) {\n"
"        PyErr_SetString(PyExc_TypeError,\n"
"                        \"The first attribute value must be a string\");\n"
"        return -1;\n"
"    }\n"
"    Py_SETREF(self->first, Py_NewRef(value));\n"
"    return 0;\n"
"}\n"
"\n"
"static PyObject *\n"
"Custom_getlast(CustomObject *self, void *closure)\n"
"{\n"
"    return Py_NewRef(self->last);\n"
"}\n"
"\n"
"static int\n"
"Custom_setlast(CustomObject *self, PyObject *value, void *closure)\n"
"{\n"
"    if (value == NULL) {\n"
"        PyErr_SetString(PyExc_TypeError, \"Cannot delete the last "
"attribute\");\n"
"        return -1;\n"
"    }\n"
"    if (!PyUnicode_Check(value)) {\n"
"        PyErr_SetString(PyExc_TypeError,\n"
"                        \"The last attribute value must be a string\");\n"
"        return -1;\n"
"    }\n"
"    Py_SETREF(self->last, Py_NewRef(value));\n"
"    return 0;\n"
"}\n"
"\n"
"static PyGetSetDef Custom_getsetters[] = {\n"
"    {\"first\", (getter) Custom_getfirst, (setter) Custom_setfirst,\n"
"     \"first name\", NULL},\n"
"    {\"last\", (getter) Custom_getlast, (setter) Custom_setlast,\n"
"     \"last name\", NULL},\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyObject *\n"
"Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))\n"
"{\n"
"    return PyUnicode_FromFormat(\"%S %S\", self->first, self->last);\n"
"}\n"
"\n"
"static PyMethodDef Custom_methods[] = {\n"
"    {\"name\", (PyCFunction) Custom_name, METH_NOARGS,\n"
"     \"Return the name, combining the first and last name\"\n"
"    },\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyTypeObject CustomType = {\n"
"    .ob_base = PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"custom3.Custom\",\n"
"    .tp_doc = PyDoc_STR(\"Custom objects\"),\n"
"    .tp_basicsize = sizeof(CustomObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,\n"
"    .tp_new = Custom_new,\n"
"    .tp_init = (initproc) Custom_init,\n"
"    .tp_dealloc = (destructor) Custom_dealloc,\n"
"    .tp_members = Custom_members,\n"
"    .tp_methods = Custom_methods,\n"
"    .tp_getset = Custom_getsetters,\n"
"};\n"
"\n"
"static PyModuleDef custommodule = {\n"
"    .m_base = PyModuleDef_HEAD_INIT,\n"
"    .m_name = \"custom3\",\n"
"    .m_doc = \"Example module that creates an extension type.\",\n"
"    .m_size = -1,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_custom3(void)\n"
"{\n"
"    PyObject *m;\n"
"    if (PyType_Ready(&CustomType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&custommodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"Custom\", (PyObject *) &CustomType) < 0) "
"{\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:541
msgid ""
"To provide greater control, over the :attr:`!first` and :attr:`!last` "
"attributes, we'll use custom getter and setter functions.  Here are the "
"functions for getting and setting the :attr:`!first` attribute::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:545
msgid ""
"static PyObject *\n"
"Custom_getfirst(CustomObject *self, void *closure)\n"
"{\n"
"    Py_INCREF(self->first);\n"
"    return self->first;\n"
"}\n"
"\n"
"static int\n"
"Custom_setfirst(CustomObject *self, PyObject *value, void *closure)\n"
"{\n"
"    PyObject *tmp;\n"
"    if (value == NULL) {\n"
"        PyErr_SetString(PyExc_TypeError, \"Cannot delete the first "
"attribute\");\n"
"        return -1;\n"
"    }\n"
"    if (!PyUnicode_Check(value)) {\n"
"        PyErr_SetString(PyExc_TypeError,\n"
"                        \"The first attribute value must be a string\");\n"
"        return -1;\n"
"    }\n"
"    tmp = self->first;\n"
"    Py_INCREF(value);\n"
"    self->first = value;\n"
"    Py_DECREF(tmp);\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:572
msgid ""
"The getter function is passed a :class:`!Custom` object and a \"closure\", "
"which is a void pointer.  In this case, the closure is ignored.  (The "
"closure supports an advanced usage in which definition data is passed to the "
"getter and setter. This could, for example, be used to allow a single set of "
"getter and setter functions that decide the attribute to get or set based on "
"data in the closure.)"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:578
msgid ""
"The setter function is passed the :class:`!Custom` object, the new value, "
"and the closure.  The new value may be ``NULL``, in which case the attribute "
"is being deleted.  In our setter, we raise an error if the attribute is "
"deleted or if its new value is not a string."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:583
msgid "We create an array of :c:type:`PyGetSetDef` structures::"
msgstr "ここでは :c:type:`PyGetSetDef` 構造体の配列をつくります::"

#: ../../extending/newtypes_tutorial.rst:585
msgid ""
"static PyGetSetDef Custom_getsetters[] = {\n"
"    {\"first\", (getter) Custom_getfirst, (setter) Custom_setfirst,\n"
"     \"first name\", NULL},\n"
"    {\"last\", (getter) Custom_getlast, (setter) Custom_setlast,\n"
"     \"last name\", NULL},\n"
"    {NULL}  /* Sentinel */\n"
"};"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:593
msgid "and register it in the :c:member:`~PyTypeObject.tp_getset` slot::"
msgstr ""
"そしてこれを :c:member:`~PyTypeObject.tp_getset` スロットに登録します::"

#: ../../extending/newtypes_tutorial.rst:595
msgid ".tp_getset = Custom_getsetters,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:597
msgid ""
"The last item in a :c:type:`PyGetSetDef` structure is the \"closure\" "
"mentioned above.  In this case, we aren't using a closure, so we just pass "
"``NULL``."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:600
msgid "We also remove the member definitions for these attributes::"
msgstr "また、メンバ定義からはこれらの属性を除いておきましょう::"

#: ../../extending/newtypes_tutorial.rst:602
msgid ""
"static PyMemberDef Custom_members[] = {\n"
"    {\"number\", Py_T_INT, offsetof(CustomObject, number), 0,\n"
"     \"custom number\"},\n"
"    {NULL}  /* Sentinel */\n"
"};"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:608
msgid ""
"We also need to update the :c:member:`~PyTypeObject.tp_init` handler to only "
"allow strings [#]_ to be passed::"
msgstr ""
"また、ここでは :c:member:`~PyTypeObject.tp_init` ハンドラも渡されるものとして"
"文字列のみを許可するように修正する必要があります [#]_::"

#: ../../extending/newtypes_tutorial.rst:611
msgid ""
"static int\n"
"Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    static char *kwlist[] = {\"first\", \"last\", \"number\", NULL};\n"
"    PyObject *first = NULL, *last = NULL, *tmp;\n"
"\n"
"    if (!PyArg_ParseTupleAndKeywords(args, kwds, \"|UUi\", kwlist,\n"
"                                     &first, &last,\n"
"                                     &self->number))\n"
"        return -1;\n"
"\n"
"    if (first) {\n"
"        tmp = self->first;\n"
"        Py_INCREF(first);\n"
"        self->first = first;\n"
"        Py_DECREF(tmp);\n"
"    }\n"
"    if (last) {\n"
"        tmp = self->last;\n"
"        Py_INCREF(last);\n"
"        self->last = last;\n"
"        Py_DECREF(tmp);\n"
"    }\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:637
msgid ""
"With these changes, we can assure that the ``first`` and ``last`` members "
"are never ``NULL`` so we can remove checks for ``NULL`` values in almost all "
"cases. This means that most of the :c:func:`Py_XDECREF` calls can be "
"converted to :c:func:`Py_DECREF` calls.  The only place we can't change "
"these calls is in the ``tp_dealloc`` implementation, where there is the "
"possibility that the initialization of these members failed in ``tp_new``."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:644
msgid ""
"We also rename the module initialization function and module name in the "
"initialization function, as we did before, and we add an extra definition to "
"the :file:`setup.py` file."
msgstr ""
"さて、先ほどもしたように、このモジュール初期化関数と初期化関数内にあるモ"
"ジュール名を変更しましょう。そして :file:`setup.py` ファイルに追加の定義をく"
"わえます。"

#: ../../extending/newtypes_tutorial.rst:650
msgid "Supporting cyclic garbage collection"
msgstr "循環ガベージコレクションをサポートする"

#: ../../extending/newtypes_tutorial.rst:652
msgid ""
"Python has a :term:`cyclic garbage collector (GC) <garbage collection>` that "
"can identify unneeded objects even when their reference counts are not zero. "
"This can happen when objects are involved in cycles.  For example, consider:"
msgstr ""
"Python は :term:`循環ガベージコレクタ (GC) 機能 <garbage collection>` をもっ"
"ており、これは不要なオブジェクトを、たとえ参照カウントがゼロでなくても発見す"
"ることができます。そのような状況はオブジェクトの参照が循環しているときに起こ"
"りえます。たとえば以下の例を考えてください:"

#: ../../extending/newtypes_tutorial.rst:656
msgid ""
">>> l = []\n"
">>> l.append(l)\n"
">>> del l"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:662
msgid ""
"In this example, we create a list that contains itself. When we delete it, "
"it still has a reference from itself. Its reference count doesn't drop to "
"zero. Fortunately, Python's cyclic garbage collector will eventually figure "
"out that the list is garbage and free it."
msgstr ""
"この例では、自分自身をふくむリストを作りました。たとえこのリストを 削除して"
"も、それは自分自身への参照をまだ持ちつづけますから、参照カウントはゼロにはな"
"りません。嬉しいことに Python には循環ガベージコレクタは最終的にはこのリスト"
"が不要であることを検出し、解放できます。"

#: ../../extending/newtypes_tutorial.rst:667
msgid ""
"In the second version of the :class:`!Custom` example, we allowed any kind "
"of object to be stored in the :attr:`!first` or :attr:`!last` attributes "
"[#]_. Besides, in the second and third versions, we allowed subclassing :"
"class:`!Custom`, and subclasses may add arbitrary attributes.  For any of "
"those two reasons, :class:`!Custom` objects can participate in cycles:"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:673
msgid ""
">>> import custom3\n"
">>> class Derived(custom3.Custom): pass\n"
"...\n"
">>> n = Derived()\n"
">>> n.some_attribute = n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:681
msgid ""
"To allow a :class:`!Custom` instance participating in a reference cycle to "
"be properly detected and collected by the cyclic GC, our :class:`!Custom` "
"type needs to fill two additional slots and to enable a flag that enables "
"these slots:"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:685
msgid ""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"#include <stddef.h> /* for offsetof() */\n"
"\n"
"typedef struct {\n"
"    PyObject_HEAD\n"
"    PyObject *first; /* first name */\n"
"    PyObject *last;  /* last name */\n"
"    int number;\n"
"} CustomObject;\n"
"\n"
"static int\n"
"Custom_traverse(CustomObject *self, visitproc visit, void *arg)\n"
"{\n"
"    Py_VISIT(self->first);\n"
"    Py_VISIT(self->last);\n"
"    return 0;\n"
"}\n"
"\n"
"static int\n"
"Custom_clear(CustomObject *self)\n"
"{\n"
"    Py_CLEAR(self->first);\n"
"    Py_CLEAR(self->last);\n"
"    return 0;\n"
"}\n"
"\n"
"static void\n"
"Custom_dealloc(CustomObject *self)\n"
"{\n"
"    PyObject_GC_UnTrack(self);\n"
"    Custom_clear(self);\n"
"    Py_TYPE(self)->tp_free((PyObject *) self);\n"
"}\n"
"\n"
"static PyObject *\n"
"Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)\n"
"{\n"
"    CustomObject *self;\n"
"    self = (CustomObject *) type->tp_alloc(type, 0);\n"
"    if (self != NULL) {\n"
"        self->first = PyUnicode_FromString(\"\");\n"
"        if (self->first == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->last = PyUnicode_FromString(\"\");\n"
"        if (self->last == NULL) {\n"
"            Py_DECREF(self);\n"
"            return NULL;\n"
"        }\n"
"        self->number = 0;\n"
"    }\n"
"    return (PyObject *) self;\n"
"}\n"
"\n"
"static int\n"
"Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    static char *kwlist[] = {\"first\", \"last\", \"number\", NULL};\n"
"    PyObject *first = NULL, *last = NULL;\n"
"\n"
"    if (!PyArg_ParseTupleAndKeywords(args, kwds, \"|UUi\", kwlist,\n"
"                                     &first, &last,\n"
"                                     &self->number))\n"
"        return -1;\n"
"\n"
"    if (first) {\n"
"        Py_SETREF(self->first, Py_NewRef(first));\n"
"    }\n"
"    if (last) {\n"
"        Py_SETREF(self->last, Py_NewRef(last));\n"
"    }\n"
"    return 0;\n"
"}\n"
"\n"
"static PyMemberDef Custom_members[] = {\n"
"    {\"number\", Py_T_INT, offsetof(CustomObject, number), 0,\n"
"     \"custom number\"},\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyObject *\n"
"Custom_getfirst(CustomObject *self, void *closure)\n"
"{\n"
"    return Py_NewRef(self->first);\n"
"}\n"
"\n"
"static int\n"
"Custom_setfirst(CustomObject *self, PyObject *value, void *closure)\n"
"{\n"
"    if (value == NULL) {\n"
"        PyErr_SetString(PyExc_TypeError, \"Cannot delete the first "
"attribute\");\n"
"        return -1;\n"
"    }\n"
"    if (!PyUnicode_Check(value)) {\n"
"        PyErr_SetString(PyExc_TypeError,\n"
"                        \"The first attribute value must be a string\");\n"
"        return -1;\n"
"    }\n"
"    Py_XSETREF(self->first, Py_NewRef(value));\n"
"    return 0;\n"
"}\n"
"\n"
"static PyObject *\n"
"Custom_getlast(CustomObject *self, void *closure)\n"
"{\n"
"    return Py_NewRef(self->last);\n"
"}\n"
"\n"
"static int\n"
"Custom_setlast(CustomObject *self, PyObject *value, void *closure)\n"
"{\n"
"    if (value == NULL) {\n"
"        PyErr_SetString(PyExc_TypeError, \"Cannot delete the last "
"attribute\");\n"
"        return -1;\n"
"    }\n"
"    if (!PyUnicode_Check(value)) {\n"
"        PyErr_SetString(PyExc_TypeError,\n"
"                        \"The last attribute value must be a string\");\n"
"        return -1;\n"
"    }\n"
"    Py_XSETREF(self->last, Py_NewRef(value));\n"
"    return 0;\n"
"}\n"
"\n"
"static PyGetSetDef Custom_getsetters[] = {\n"
"    {\"first\", (getter) Custom_getfirst, (setter) Custom_setfirst,\n"
"     \"first name\", NULL},\n"
"    {\"last\", (getter) Custom_getlast, (setter) Custom_setlast,\n"
"     \"last name\", NULL},\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyObject *\n"
"Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))\n"
"{\n"
"    return PyUnicode_FromFormat(\"%S %S\", self->first, self->last);\n"
"}\n"
"\n"
"static PyMethodDef Custom_methods[] = {\n"
"    {\"name\", (PyCFunction) Custom_name, METH_NOARGS,\n"
"     \"Return the name, combining the first and last name\"\n"
"    },\n"
"    {NULL}  /* Sentinel */\n"
"};\n"
"\n"
"static PyTypeObject CustomType = {\n"
"    .ob_base = PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"custom4.Custom\",\n"
"    .tp_doc = PyDoc_STR(\"Custom objects\"),\n"
"    .tp_basicsize = sizeof(CustomObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | "
"Py_TPFLAGS_HAVE_GC,\n"
"    .tp_new = Custom_new,\n"
"    .tp_init = (initproc) Custom_init,\n"
"    .tp_dealloc = (destructor) Custom_dealloc,\n"
"    .tp_traverse = (traverseproc) Custom_traverse,\n"
"    .tp_clear = (inquiry) Custom_clear,\n"
"    .tp_members = Custom_members,\n"
"    .tp_methods = Custom_methods,\n"
"    .tp_getset = Custom_getsetters,\n"
"};\n"
"\n"
"static PyModuleDef custommodule = {\n"
"    .m_base = PyModuleDef_HEAD_INIT,\n"
"    .m_name = \"custom4\",\n"
"    .m_doc = \"Example module that creates an extension type.\",\n"
"    .m_size = -1,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_custom4(void)\n"
"{\n"
"    PyObject *m;\n"
"    if (PyType_Ready(&CustomType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&custommodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"Custom\", (PyObject *) &CustomType) < 0) "
"{\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:688
msgid ""
"First, the traversal method lets the cyclic GC know about subobjects that "
"could participate in cycles::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:691
msgid ""
"static int\n"
"Custom_traverse(CustomObject *self, visitproc visit, void *arg)\n"
"{\n"
"    int vret;\n"
"    if (self->first) {\n"
"        vret = visit(self->first, arg);\n"
"        if (vret != 0)\n"
"            return vret;\n"
"    }\n"
"    if (self->last) {\n"
"        vret = visit(self->last, arg);\n"
"        if (vret != 0)\n"
"            return vret;\n"
"    }\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:708
msgid ""
"For each subobject that can participate in cycles, we need to call the :c:"
"func:`!visit` function, which is passed to the traversal method. The :c:func:"
"`!visit` function takes as arguments the subobject and the extra argument "
"*arg* passed to the traversal method.  It returns an integer value that must "
"be returned if it is non-zero."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:714
msgid ""
"Python provides a :c:func:`Py_VISIT` macro that automates calling visit "
"functions.  With :c:func:`Py_VISIT`, we can minimize the amount of "
"boilerplate in ``Custom_traverse``::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:718
msgid ""
"static int\n"
"Custom_traverse(CustomObject *self, visitproc visit, void *arg)\n"
"{\n"
"    Py_VISIT(self->first);\n"
"    Py_VISIT(self->last);\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:727
msgid ""
"The :c:member:`~PyTypeObject.tp_traverse` implementation must name its "
"arguments exactly *visit* and *arg* in order to use :c:func:`Py_VISIT`."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:730
msgid ""
"Second, we need to provide a method for clearing any subobjects that can "
"participate in cycles::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:733
msgid ""
"static int\n"
"Custom_clear(CustomObject *self)\n"
"{\n"
"    Py_CLEAR(self->first);\n"
"    Py_CLEAR(self->last);\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:741
msgid ""
"Notice the use of the :c:func:`Py_CLEAR` macro.  It is the recommended and "
"safe way to clear data attributes of arbitrary types while decrementing "
"their reference counts.  If you were to call :c:func:`Py_XDECREF` instead on "
"the attribute before setting it to ``NULL``, there is a possibility that the "
"attribute's destructor would call back into code that reads the attribute "
"again (*especially* if there is a reference cycle)."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:749
msgid "You could emulate :c:func:`Py_CLEAR` by writing::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:751
msgid ""
"PyObject *tmp;\n"
"tmp = self->first;\n"
"self->first = NULL;\n"
"Py_XDECREF(tmp);"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:756
msgid ""
"Nevertheless, it is much easier and less error-prone to always use :c:func:"
"`Py_CLEAR` when deleting an attribute.  Don't try to micro-optimize at the "
"expense of robustness!"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:760
msgid ""
"The deallocator ``Custom_dealloc`` may call arbitrary code when clearing "
"attributes.  It means the circular GC can be triggered inside the function. "
"Since the GC assumes reference count is not zero, we need to untrack the "
"object from the GC by calling :c:func:`PyObject_GC_UnTrack` before clearing "
"members. Here is our reimplemented deallocator using :c:func:"
"`PyObject_GC_UnTrack` and ``Custom_clear``::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:767
msgid ""
"static void\n"
"Custom_dealloc(CustomObject *self)\n"
"{\n"
"    PyObject_GC_UnTrack(self);\n"
"    Custom_clear(self);\n"
"    Py_TYPE(self)->tp_free((PyObject *) self);\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:775
msgid ""
"Finally, we add the :c:macro:`Py_TPFLAGS_HAVE_GC` flag to the class flags::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:777
msgid ""
".tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:779
msgid ""
"That's pretty much it.  If we had written custom :c:member:`~PyTypeObject."
"tp_alloc` or :c:member:`~PyTypeObject.tp_free` handlers, we'd need to modify "
"them for cyclic garbage collection.  Most extensions will use the versions "
"automatically provided."
msgstr ""
"これで完了です。 :c:member:`~PyTypeObject.tp_alloc` スロットまたは :c:member:"
"`~PyTypeObject.tp_free` ハンドラが書かれていれば、それらを循環ガベージコレク"
"ションに使えるよう修正すればよいのです。ほとんどの拡張機能は自動的に提供され"
"るバージョンを使うでしょう。"

#: ../../extending/newtypes_tutorial.rst:785
msgid "Subclassing other types"
msgstr "他の型のサブクラスを作る"

#: ../../extending/newtypes_tutorial.rst:787
msgid ""
"It is possible to create new extension types that are derived from existing "
"types. It is easiest to inherit from the built in types, since an extension "
"can easily use the :c:type:`PyTypeObject` it needs. It can be difficult to "
"share these :c:type:`PyTypeObject` structures between extension modules."
msgstr ""
"既存の型を継承した新しい拡張型を作成することができます。組み込み型から継承す"
"るのは特に簡単です。必要な :c:type:`PyTypeObject` を簡単に利用できるからで"
"す。それに比べて、 :c:type:`PyTypeObject` 構造体を拡張モジュール間で共有する"
"のは難しいです。"

#: ../../extending/newtypes_tutorial.rst:792
msgid ""
"In this example we will create a :class:`!SubList` type that inherits from "
"the built-in :class:`list` type. The new type will be completely compatible "
"with regular lists, but will have an additional :meth:`!increment` method "
"that increases an internal counter:"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:797
msgid ""
">>> import sublist\n"
">>> s = sublist.SubList(range(3))\n"
">>> s.extend(s)\n"
">>> print(len(s))\n"
"6\n"
">>> print(s.increment())\n"
"1\n"
">>> print(s.increment())\n"
"2"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:809
msgid ""
"#define PY_SSIZE_T_CLEAN\n"
"#include <Python.h>\n"
"\n"
"typedef struct {\n"
"    PyListObject list;\n"
"    int state;\n"
"} SubListObject;\n"
"\n"
"static PyObject *\n"
"SubList_increment(SubListObject *self, PyObject *unused)\n"
"{\n"
"    self->state++;\n"
"    return PyLong_FromLong(self->state);\n"
"}\n"
"\n"
"static PyMethodDef SubList_methods[] = {\n"
"    {\"increment\", (PyCFunction) SubList_increment, METH_NOARGS,\n"
"     PyDoc_STR(\"increment state counter\")},\n"
"    {NULL},\n"
"};\n"
"\n"
"static int\n"
"SubList_init(SubListObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    if (PyList_Type.tp_init((PyObject *) self, args, kwds) < 0)\n"
"        return -1;\n"
"    self->state = 0;\n"
"    return 0;\n"
"}\n"
"\n"
"static PyTypeObject SubListType = {\n"
"    PyVarObject_HEAD_INIT(NULL, 0)\n"
"    .tp_name = \"sublist.SubList\",\n"
"    .tp_doc = PyDoc_STR(\"SubList objects\"),\n"
"    .tp_basicsize = sizeof(SubListObject),\n"
"    .tp_itemsize = 0,\n"
"    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,\n"
"    .tp_init = (initproc) SubList_init,\n"
"    .tp_methods = SubList_methods,\n"
"};\n"
"\n"
"static PyModuleDef sublistmodule = {\n"
"    PyModuleDef_HEAD_INIT,\n"
"    .m_name = \"sublist\",\n"
"    .m_doc = \"Example module that creates an extension type.\",\n"
"    .m_size = -1,\n"
"};\n"
"\n"
"PyMODINIT_FUNC\n"
"PyInit_sublist(void)\n"
"{\n"
"    PyObject *m;\n"
"    SubListType.tp_base = &PyList_Type;\n"
"    if (PyType_Ready(&SubListType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&sublistmodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"SubList\", (PyObject *) &SubListType) < "
"0) {\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}\n"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:812
msgid ""
"As you can see, the source code closely resembles the :class:`!Custom` "
"examples in previous sections. We will break down the main differences "
"between them. ::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:815
msgid ""
"typedef struct {\n"
"    PyListObject list;\n"
"    int state;\n"
"} SubListObject;"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:820
msgid ""
"The primary difference for derived type objects is that the base type's "
"object structure must be the first value.  The base type will already "
"include the :c:func:`PyObject_HEAD` at the beginning of its structure."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:824
msgid ""
"When a Python object is a :class:`!SubList` instance, its ``PyObject *`` "
"pointer can be safely cast to both ``PyListObject *`` and ``SubListObject "
"*``::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:827
msgid ""
"static int\n"
"SubList_init(SubListObject *self, PyObject *args, PyObject *kwds)\n"
"{\n"
"    if (PyList_Type.tp_init((PyObject *) self, args, kwds) < 0)\n"
"        return -1;\n"
"    self->state = 0;\n"
"    return 0;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:836
msgid ""
"We see above how to call through to the :meth:`~object.__init__` method of "
"the base type."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:839
msgid ""
"This pattern is important when writing a type with custom :c:member:"
"`~PyTypeObject.tp_new` and :c:member:`~PyTypeObject.tp_dealloc` members.  "
"The :c:member:`~PyTypeObject.tp_new` handler should not actually create the "
"memory for the object with its :c:member:`~PyTypeObject.tp_alloc`, but let "
"the base class handle it by calling its own :c:member:`~PyTypeObject.tp_new`."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:845
msgid ""
"The :c:type:`PyTypeObject` struct supports a :c:member:`~PyTypeObject."
"tp_base` specifying the type's concrete base class.  Due to cross-platform "
"compiler issues, you can't fill that field directly with a reference to :c:"
"type:`PyList_Type`; it should be done later in the module initialization "
"function::"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:851
msgid ""
"PyMODINIT_FUNC\n"
"PyInit_sublist(void)\n"
"{\n"
"    PyObject* m;\n"
"    SubListType.tp_base = &PyList_Type;\n"
"    if (PyType_Ready(&SubListType) < 0)\n"
"        return NULL;\n"
"\n"
"    m = PyModule_Create(&sublistmodule);\n"
"    if (m == NULL)\n"
"        return NULL;\n"
"\n"
"    if (PyModule_AddObjectRef(m, \"SubList\", (PyObject *) &SubListType) < "
"0) {\n"
"        Py_DECREF(m);\n"
"        return NULL;\n"
"    }\n"
"\n"
"    return m;\n"
"}"
msgstr ""

#: ../../extending/newtypes_tutorial.rst:871
msgid ""
"Before calling :c:func:`PyType_Ready`, the type structure must have the :c:"
"member:`~PyTypeObject.tp_base` slot filled in.  When we are deriving an "
"existing type, it is not necessary to fill out the :c:member:`~PyTypeObject."
"tp_alloc` slot with :c:func:`PyType_GenericNew` -- the allocation function "
"from the base type will be inherited."
msgstr ""
":c:func:`PyType_Read` を呼ぶ前に、型の構造体の :c:member:`~PyTypeObject."
"tp_base` スロットは埋められていなければなりません。既存の型を継承する際に"
"は、 :c:member:`~PyTypeObject.tp_alloc` スロットを :c:func:"
"`PyType_GenericNew` で埋める必要はありません。 -- 基底型のアロケーション関数"
"が継承されます。"

#: ../../extending/newtypes_tutorial.rst:877
msgid ""
"After that, calling :c:func:`PyType_Ready` and adding the type object to the "
"module is the same as with the basic :class:`!Custom` examples."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:882
msgid "Footnotes"
msgstr "脚注"

#: ../../extending/newtypes_tutorial.rst:883
msgid ""
"This is true when we know that the object is a basic type, like a string or "
"a float."
msgstr ""
"これはそのオブジェクトが文字列や実数などの基本タイプであるような時に成り立ち"
"ます。"

#: ../../extending/newtypes_tutorial.rst:886
msgid ""
"We relied on this in the :c:member:`~PyTypeObject.tp_dealloc` handler in "
"this example, because our type doesn't support garbage collection."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:889
msgid ""
"We now know that the first and last members are strings, so perhaps we could "
"be less careful about decrementing their reference counts, however, we "
"accept instances of string subclasses.  Even though deallocating normal "
"strings won't call back into our objects, we can't guarantee that "
"deallocating an instance of a string subclass won't call back into our "
"objects."
msgstr ""

#: ../../extending/newtypes_tutorial.rst:895
msgid ""
"Also, even with our attributes restricted to strings instances, the user "
"could pass arbitrary :class:`str` subclasses and therefore still create "
"reference cycles."
msgstr ""