# 整数型オブジェクト (integer object)

すべての整数は任意の長さをもつ "long" 整数として実装されます。

エラーが起きると、ほとんどの `PyLong_As*` API は `(return type)-1` を返しますが、これは数値と見分けが付きません。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

type PyLongObject
  次に属します: Limited API (不透明な構造体として).

  この `PyObject` のサブタイプは整数型を表現します。

PyTypeObject PyLong_Type
  次に属します: Stable ABI.

  この `PyTypeObject` のインスタンスは Python 整数型を表現します。これは Python レイヤにおける `int` と同じオブジェクトです。

int PyLong_Check(PyObject *p)

  引数が `PyLongObject` か `PyLongObject` のサブタイプであるときに真を返します。この関数は常に成功します。

int PyLong_CheckExact(PyObject *p)

  引数が `PyLongObject` であるが `PyLongObject` のサブタイプでないときに真を返します。この関数は常に成功します。

PyObject *PyLong_FromLong(long v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  v から新たな `PyLongObject` オブジェクトを生成して返します。失敗のときには `NULL` を返します。

  CPython 実装の詳細: CPython keeps an array of integer objects for all integers between `-5` and `256`. When you create an int in that range you actually just get back a reference to the existing object.

PyObject *PyLong_FromUnsignedLong(unsigned long v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  Cの unsigned long から新たな `PyLongObject` オブジェクトを生成して返します。失敗した際には `NULL` を返します。

PyObject *PyLong_FromSsize_t(Py_ssize_t v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  C の `Py_ssize_t` 型から新たな `PyLongObject` オブジェクトを生成して返します。 失敗のときには `NULL` を返します。

PyObject *PyLong_FromSize_t(size_t v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  C の `size_t` 型から新たな `PyLongObject` オブジェクトを生成して返します。 失敗のときには `NULL` を返します。

PyObject *PyLong_FromLongLong(long long v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  C の long long 型から新たな `PyLongObject` オブジェクトを生成して返します。失敗のときには `NULL` を返します。

PyObject *PyLong_FromInt32(int32_t value)
PyObject *PyLong_FromInt64(int64_t value)
  次に属します: Stable ABI (バージョン 3.14 より).

  Return a new `PyLongObject` object from a signed C int32_t or int64_t, or `NULL` with an exception set on failure.

  Added in version 3.14.

PyObject *PyLong_FromUnsignedLongLong(unsigned long long v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  C の unsigned long long 型から新たな `PyLongObject` オブジェクトを生成して返します。失敗のときには `NULL` を返します。

PyObject *PyLong_FromUInt32(uint32_t value)
PyObject *PyLong_FromUInt64(uint64_t value)
  次に属します: Stable ABI (バージョン 3.14 より).

  Return a new `PyLongObject` object from an unsigned C uint32_t or uint64_t, or `NULL` with an exception set on failure.

  Added in version 3.14.

PyObject *PyLong_FromDouble(double v)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  v の整数部から新たな `PyLongObject` オブジェクトを生成して返します。失敗のときには `NULL` を返します。

PyObject *PyLong_FromString(const char *str, char **pend, int base)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  Return a new `PyLongObject` based on the string value in str, which is interpreted according to the radix in base, or `NULL` on failure. If pend is non-`NULL`, *pend will point to the end of str on success or to the first character that could not be processed on error. If base is `0`, str is interpreted using the 整数リテラル definition; in this case, leading zeros in a non-zero decimal number raises a `ValueError`. If base is not `0`, it must be between `2` and `36`, inclusive. Leading and trailing whitespace and single underscores after a base specifier and between digits are ignored. If there are no digits or str is not NULL-terminated following the digits and trailing whitespace, `ValueError` will be raised.

  参考

  `PyLong_AsNativeBytes()` and `PyLong_FromNativeBytes()` functions can be used to convert a `PyLongObject` to/from an array of bytes in base `256`.

PyObject *PyLong_FromUnicodeObject(PyObject *u, int base)
  戻り値: 新しい参照。

  Convert a sequence of Unicode digits in the string u to a Python integer value.

  Added in version 3.3.

PyObject *PyLong_FromVoidPtr(void *p)
  戻り値: 新しい参照。 次に属します: Stable ABI.

  ポインタ p から Python 整数値を生成します。ポインタの値は `PyLong_AsVoidPtr()` を適用した結果から取得されます。

PyObject *PyLong_FromNativeBytes(const void *buffer, size_t n_bytes, int flags)
  次に属します: Stable ABI (バージョン 3.14 より).

  Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as a two's-complement signed number.

  flags are as for `PyLong_AsNativeBytes()`. Passing `-1` will select the native endian that CPython was compiled with and assume that the most-significant bit is a sign bit. Passing `Py_ASNATIVEBYTES_UNSIGNED_BUFFER` will produce the same result as calling `PyLong_FromUnsignedNativeBytes()`. Other flags are ignored.

  Added in version 3.13.

PyObject *PyLong_FromUnsignedNativeBytes(const void *buffer, size_t n_bytes, int flags)
  次に属します: Stable ABI (バージョン 3.14 より).

  Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as an unsigned number.

  flags are as for `PyLong_AsNativeBytes()`. Passing `-1` will select the native endian that CPython was compiled with and assume that the most-significant bit is not a sign bit. Flags other than endian are ignored.

  Added in version 3.13.

long PyLong_AsLong(PyObject *obj)
  次に属します: Stable ABI.

  Return a C long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  もし obj の値が long の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

  long PyLong_AS_LONG(PyObject *obj)

    A soft deprecated alias. Exactly equivalent to the preferred `PyLong_AsLong`. In particular, it can fail with `OverflowError` or another exception.

    バージョン 3.14 で非推奨: The function is soft deprecated.

int PyLong_AsInt(PyObject *obj)
  次に属します: Stable ABI (バージョン 3.13 より).

  Similar to `PyLong_AsLong()`, but store the result in a C int instead of a C long.

  Added in version 3.13.

long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)
  次に属します: Stable ABI.

  Return a C long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  If the value of obj is greater than `LONG_MAX` or less than `LONG_MIN`, set *overflow to `1` or `-1`, respectively, and return `-1`; otherwise, set *overflow to `0`. If any other exception occurs set *overflow to `0` and return `-1` as usual.

  エラーが起きたときに `-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

long long PyLong_AsLongLong(PyObject *obj)
  次に属します: Stable ABI.

  Return a C long long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  もし obj の値が long long の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

long long PyLong_AsLongLongAndOverflow(PyObject *obj, int *overflow)
  次に属します: Stable ABI.

  Return a C long long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  If the value of obj is greater than `LLONG_MAX` or less than `LLONG_MIN`, set *overflow to `1` or `-1`, respectively, and return `-1`; otherwise, set *overflow to `0`. If any other exception occurs set *overflow to `0` and return `-1` as usual.

  エラーが起きたときに `-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  Added in version 3.2.

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
  次に属します: Stable ABI.

  pylong を表す C の `Py_ssize_t` を返します。 pylong は `PyLongObject` のインスタンスでなければなりません。

  もし pylong の値が `Py_ssize_t` の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

unsigned long PyLong_AsUnsignedLong(PyObject *pylong)
  次に属します: Stable ABI.

  pylong を表す C の unsigned long を返します。 pylong は `PyLongObject` のインスタンスでなければなりません。

  もし pylong の値が unsigned long の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `(unsigned long)-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

size_t PyLong_AsSize_t(PyObject *pylong)
  次に属します: Stable ABI.

  pylong を表す C の `size_t` を返します。 pylong は `PyLongObject` のインスタンスでなければなりません。

  もし pylong の値が `size_t` の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `(size_t)-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

unsigned long long PyLong_AsUnsignedLongLong(PyObject *pylong)
  次に属します: Stable ABI.

  pylong を表す C の unsigned long long を返します。 pylong は `PyLongObject` のインスタンスでなければなりません。

  もし pylong の値が unsigned long long の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `(unsigned long long)-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.1 で変更: 負 pylong を指定した際に `TypeError` ではなく、 `OverflowError` を送出するようになりました。

unsigned long PyLong_AsUnsignedLongMask(PyObject *obj)
  次に属します: Stable ABI.

  Return a C unsigned long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  obj の値が unsigned long の範囲から外れていた場合は、 `ULONG_MAX + 1` を法とした剰余を返します。

  エラーが起きたときに `(unsigned long)-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

unsigned long long PyLong_AsUnsignedLongLongMask(PyObject *obj)
  次に属します: Stable ABI.

  Return a C unsigned long long representation of obj. If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  obj の値が unsigned long long の範囲から外れていた場合は、 `ULLONG_MAX + 1` を法とした剰余を返します。

  エラーが起きたときに `(unsigned long long)-1` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

  バージョン 3.8 で変更: 可能であれば `__index__()` を使うようになりました。

  バージョン 3.10 で変更: This function will no longer use `__int__()`.

int PyLong_AsInt32(PyObject *obj, int32_t *value)
int PyLong_AsInt64(PyObject *obj, int64_t *value)
  次に属します: Stable ABI (バージョン 3.14 より).

  Set *value to a signed C int32_t or int64_t representation of obj.

  If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  If the obj value is out of range, raise an `OverflowError`.

  Set *value and return `0` on success. Set an exception and return `-1` on error.

  value must not be `NULL`.

  Added in version 3.14.

int PyLong_AsUInt32(PyObject *obj, uint32_t *value)
int PyLong_AsUInt64(PyObject *obj, uint64_t *value)
  次に属します: Stable ABI (バージョン 3.14 より).

  Set *value to an unsigned C uint32_t or uint64_t representation of obj.

  If obj is not an instance of `PyLongObject`, first call its `__index__()` method (if present) to convert it to a `PyLongObject`.

  - If obj is negative, raise a `ValueError`.

  - If the obj value is out of range, raise an `OverflowError`.

  Set *value and return `0` on success. Set an exception and return `-1` on error.

  value must not be `NULL`.

  Added in version 3.14.

double PyLong_AsDouble(PyObject *pylong)
  次に属します: Stable ABI.

  pylong を表す C の double を返します。 pylong は `PyLongObject` のインスタンスでなければなりません。

  もし pylong の値が double の範囲外であれば、 `OverflowError` を送出します。

  エラーが起きたときに `-1.0` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

void *PyLong_AsVoidPtr(PyObject *pylong)
  次に属します: Stable ABI.

  Python の整数型を指す pylong を、 C の void ポインタに変換します。 pylong を変換できなければ、 `OverflowError` を送出します。この関数は `PyLong_FromVoidPtr()` で値を生成するときに使うような void ポインタ型を生成できるだけです。

  エラーが起きたときに `NULL` を返します。 見分けを付けるためには `PyErr_Occurred()` を使ってください。

Py_ssize_t PyLong_AsNativeBytes(PyObject *pylong, void *buffer, Py_ssize_t n_bytes, int flags)
  次に属します: Stable ABI (バージョン 3.14 より).

  Copy the Python integer value pylong to a native buffer of size n_bytes. The flags can be set to `-1` to behave similarly to a C cast, or to values documented below to control the behavior.

  Returns `-1` with an exception raised on error. This may happen if pylong cannot be interpreted as an integer, or if pylong was negative and the `Py_ASNATIVEBYTES_REJECT_NEGATIVE` flag was set.

  Otherwise, returns the number of bytes required to store the value. If this is equal to or less than n_bytes, the entire value was copied. All n_bytes of the buffer are written: large buffers are padded with zeroes.

  If the returned value is greater than n_bytes, the value was truncated: as many of the lowest bits of the value as could fit are written, and the higher bits are ignored. This matches the typical behavior of a C-style downcast.

  注釈

  Overflow is not considered an error. If the returned value is larger than n_bytes, most significant bits were discarded.

  `0` will never be returned.

  Values are always copied as two's-complement.

  Usage example:

      int32_t value;
      Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, &value, sizeof(value), -1);
      if (bytes < 0) {
          // Failed. A Python exception was set with the reason.
          return NULL;
      }
      else if (bytes <= (Py_ssize_t)sizeof(value)) {
          // Success!
      }
      else {
          // Overflow occurred, but 'value' contains the truncated
          // lowest bits of pylong.
      }

  Passing zero to n_bytes will return the size of a buffer that would be large enough to hold the value. This may be larger than technically necessary, but not unreasonably so. If n_bytes=0, buffer may be `NULL`.

  注釈

  Passing n_bytes=0 to this function is not an accurate way to determine the bit length of the value.

  To get at the entire Python value of an unknown size, the function can be called twice: first to determine the buffer size, then to fill it:

      // Ask how much space we need.
      Py_ssize_t expected = PyLong_AsNativeBytes(pylong, NULL, 0, -1);
      if (expected < 0) {
          // Failed. A Python exception was set with the reason.
          return NULL;
      }
      assert(expected != 0);  // Impossible per the API definition.
      uint8_t *bignum = malloc(expected);
      if (!bignum) {
          PyErr_SetString(PyExc_MemoryError, "bignum malloc failed.");
          return NULL;
      }
      // Safely get the entire value.
      Py_ssize_t bytes = PyLong_AsNativeBytes(pylong, bignum, expected, -1);
      if (bytes < 0) {  // Exception has been set.
          free(bignum);
          return NULL;
      }
      else if (bytes > expected) {  // This should not be possible.
          PyErr_SetString(PyExc_RuntimeError,
              "Unexpected bignum truncation after a size check.");
          free(bignum);
          return NULL;
      }
      // The expected success given the above pre-check.
      // ... use bignum ...
      free(bignum);

  flags is either `-1` (`Py_ASNATIVEBYTES_DEFAULTS`) to select defaults that behave most like a C cast, or a combination of the other flags in the table below. Note that `-1` cannot be combined with other flags.

  Currently, `-1` corresponds to `Py_ASNATIVEBYTES_NATIVE_ENDIAN | Py_ASNATIVEBYTES_UNSIGNED_BUFFER`.

  Flag | 値
  --- | ---
  Py_ASNATIVEBYTES_DEFAULTS | `-1`
  Py_ASNATIVEBYTES_BIG_ENDIAN | `0`
  Py_ASNATIVEBYTES_LITTLE_ENDIAN | `1`
  Py_ASNATIVEBYTES_NATIVE_ENDIAN | `3`
  Py_ASNATIVEBYTES_UNSIGNED_BUFFER | `4`
  Py_ASNATIVEBYTES_REJECT_NEGATIVE | `8`
  Py_ASNATIVEBYTES_ALLOW_INDEX | `16`

  Specifying `Py_ASNATIVEBYTES_NATIVE_ENDIAN` will override any other endian flags. Passing `2` is reserved.

  By default, sufficient buffer will be requested to include a sign bit. For example, when converting 128 with n_bytes=1, the function will return 2 (or more) in order to store a zero sign bit.

  If `Py_ASNATIVEBYTES_UNSIGNED_BUFFER` is specified, a zero sign bit will be omitted from size calculations. This allows, for example, 128 to fit in a single-byte buffer. If the destination buffer is later treated as signed, a positive input value may become negative. Note that the flag does not affect handling of negative values: for those, space for a sign bit is always requested.

  Specifying `Py_ASNATIVEBYTES_REJECT_NEGATIVE` causes an exception to be set if pylong is negative. Without this flag, negative values will be copied provided there is enough space for at least one sign bit, regardless of whether `Py_ASNATIVEBYTES_UNSIGNED_BUFFER` was specified.

  If `Py_ASNATIVEBYTES_ALLOW_INDEX` is specified and a non-integer value is passed, its `__index__()` method will be called first. This may result in Python code executing and other threads being allowed to run, which could cause changes to other objects or values in use. When flags is `-1`, this option is not set, and non-integer values will raise `TypeError`.

  注釈

  With the default flags (`-1`, or UNSIGNED_BUFFER without REJECT_NEGATIVE), multiple Python integers can map to a single value without overflow. For example, both `255` and `-1` fit a single-byte buffer and set all its bits. This matches typical C cast behavior.

  Added in version 3.13.

int PyLong_GetSign(PyObject *obj, int *sign)

  Get the sign of the integer object obj.

  On success, set *sign to the integer sign (0, -1 or +1 for zero, negative or positive integer, respectively) and return 0.

  On failure, return -1 with an exception set. This function always succeeds if obj is a `PyLongObject` or its subtype.

  Added in version 3.14.

int PyLong_IsPositive(PyObject *obj)

  Check if the integer object obj is positive (`obj > 0`).

  If obj is an instance of `PyLongObject` or its subtype, return `1` when it's positive and `0` otherwise. Else set an exception and return `-1`.

  Added in version 3.14.

int PyLong_IsNegative(PyObject *obj)

  Check if the integer object obj is negative (`obj < 0`).

  If obj is an instance of `PyLongObject` or its subtype, return `1` when it's negative and `0` otherwise. Else set an exception and return `-1`.

  Added in version 3.14.

int PyLong_IsZero(PyObject *obj)

  Check if the integer object obj is zero.

  If obj is an instance of `PyLongObject` or its subtype, return `1` when it's zero and `0` otherwise. Else set an exception and return `-1`.

  Added in version 3.14.

PyObject *PyLong_GetInfo(void)
  次に属します: Stable ABI.

  On success, return a read only named tuple, that holds information about Python's internal representation of integers. See `sys.int_info` for description of individual fields.

  On failure, return `NULL` with an exception set.

  Added in version 3.1.

int PyUnstable_Long_IsCompact(const PyLongObject *op)
  これは Unstable APIです。マイナーリリースで予告なく変更されることがあります。

  Return 1 if op is compact, 0 otherwise.

  This function makes it possible for performance-critical code to implement a “fast path” for small integers. For compact values use `PyUnstable_Long_CompactValue()`; for others fall back to a `PyLong_As*` function or `PyLong_AsNativeBytes()`.

  The speedup is expected to be negligible for most users.

  Exactly what values are considered compact is an implementation detail and is subject to change.

  Added in version 3.12.

Py_ssize_t PyUnstable_Long_CompactValue(const PyLongObject *op)
  これは Unstable APIです。マイナーリリースで予告なく変更されることがあります。

  If op is compact, as determined by `PyUnstable_Long_IsCompact()`, return its value.

  Otherwise, the return value is undefined.

  Added in version 3.12.

## Export API

Added in version 3.14.

struct PyLongLayout

  Layout of an array of "digits" ("limbs" in the GMP terminology), used to represent absolute value for arbitrary precision integers.

  Use `PyLong_GetNativeLayout()` to get the native layout of Python `int` objects, used internally for integers with "big enough" absolute value.

  See also `sys.int_info` which exposes similar information in Python.

  uint8_t bits_per_digit

    Bits per digit. For example, a 15 bit digit means that bits 0-14 contain meaningful information.

  uint8_t digit_size

    Digit size in bytes. For example, a 15 bit digit will require at least 2 bytes.

  int8_t digits_order

    Digits order:

    - `1` for most significant digit first

    - `-1` for least significant digit first

  int8_t digit_endianness

    Digit endianness:

    - `1` for most significant byte first (big endian)

    - `-1` for least significant byte first (little endian)

const PyLongLayout *PyLong_GetNativeLayout(void)

  Get the native layout of Python `int` objects.

  See the `PyLongLayout` structure.

  The function must not be called before Python initialization nor after Python finalization. The returned layout is valid until Python is finalized. The layout is the same for all Python sub-interpreters in a process, and so it can be cached.

struct PyLongExport

  Export of a Python `int` object.

  There are two cases:

  - If `digits` is `NULL`, only use the `value` member.

  - If `digits` is not `NULL`, use `negative`, `ndigits` and `digits` members.

  int64_t value

    The native integer value of the exported `int` object. Only valid if `digits` is `NULL`.

  uint8_t negative

    `1` if the number is negative, `0` otherwise. Only valid if `digits` is not `NULL`.

  Py_ssize_t ndigits

    Number of digits in `digits` array. Only valid if `digits` is not `NULL`.

  const void *digits

    Read-only array of unsigned digits. Can be `NULL`.

int PyLong_Export(PyObject *obj, PyLongExport *export_long)

  Export a Python `int` object.

  export_long must point to a `PyLongExport` structure allocated by the caller. It must not be `NULL`.

  On success, fill in *export_long and return `0`. On error, set an exception and return `-1`.

  `PyLong_FreeExport()` must be called when the export is no longer needed.

  > CPython 実装の詳細: This function always succeeds if obj is a Python `int` object or a subclass.

void PyLong_FreeExport(PyLongExport *export_long)

  Release the export export_long created by `PyLong_Export()`.

  CPython 実装の詳細: Calling `PyLong_FreeExport()` is optional if export_long->digits is `NULL`.

## PyLongWriter API

The `PyLongWriter` API can be used to import an integer.

Added in version 3.14.

struct PyLongWriter

  A Python `int` writer instance.

  The instance must be destroyed by `PyLongWriter_Finish()` or `PyLongWriter_Discard()`.

PyLongWriter *PyLongWriter_Create(int negative, Py_ssize_t ndigits, void **digits)

  Create a `PyLongWriter`.

  On success, allocate *digits and return a writer. On error, set an exception and return `NULL`.

  negative is `1` if the number is negative, or `0` otherwise.

  ndigits is the number of digits in the digits array. It must be greater than 0.

  digits must not be NULL.

  After a successful call to this function, the caller should fill in the array of digits digits and then call `PyLongWriter_Finish()` to get a Python `int`. The layout of digits is described by `PyLong_GetNativeLayout()`.

  Digits must be in the range [`0`; `(1 << bits_per_digit) - 1`] (where the `bits_per_digit` is the number of bits per digit). Any unused most significant digits must be set to `0`.

  Alternately, call `PyLongWriter_Discard()` to destroy the writer instance without creating an `int` object.

PyObject *PyLongWriter_Finish(PyLongWriter *writer)
  戻り値: 新しい参照。

  Finish a `PyLongWriter` created by `PyLongWriter_Create()`.

  On success, return a Python `int` object. On error, set an exception and return `NULL`.

  The function takes care of normalizing the digits and converts the object to a compact integer if needed.

  The writer instance and the digits array are invalid after the call.

void PyLongWriter_Discard(PyLongWriter *writer)

  Discard a `PyLongWriter` created by `PyLongWriter_Create()`.

  If writer is `NULL`, no operation is performed.

  The writer instance and the digits array are invalid after the call.