# 集合物件

This section details the public API for `set` and `frozenset` objects. Any functionality not listed below is best accessed using either the abstract object protocol (including `PyObject_CallMethod()`, `PyObject_RichCompareBool()`, `PyObject_Hash()`, `PyObject_Repr()`, `PyObject_IsTrue()`, `PyObject_Print()`, and `PyObject_GetIter()`) or the abstract number protocol (including `PyNumber_And()`, `PyNumber_Subtract()`, `PyNumber_Or()`, `PyNumber_Xor()`, `PyNumber_InPlaceAnd()`, `PyNumber_InPlaceSubtract()`, `PyNumber_InPlaceOr()`, and `PyNumber_InPlaceXor()`).

type PySetObject

  This subtype of `PyObject` is used to hold the internal data for both `set` and `frozenset` objects. It is like a `PyDictObject` in that it is a fixed size for small sets (much like tuple storage) and will point to a separate, variable sized block of memory for medium and large sized sets (much like list storage). None of the fields of this structure should be considered public and all are subject to change. All access should be done through the documented API rather than by manipulating the values in the structure.

PyTypeObject PySet_Type
  為 穩定 ABI 的一部分.

  This is an instance of `PyTypeObject` representing the Python `set` type.

PyTypeObject PyFrozenSet_Type
  為 穩定 ABI 的一部分.

  This is an instance of `PyTypeObject` representing the Python `frozenset` type.

The following type check macros work on pointers to any Python object. Likewise, the constructor functions work with any iterable Python object.

int PySet_Check( PyObject *p)

  如果 p 是 `set` 物件或是子類別的實例，則回傳 true。此函式總會成功執行。

int PyFrozenSet_Check( PyObject *p)

  如果 p 是 `frozenset` 物件或是子類別的實例，則回傳 true。此函式總會成功執行。

int PyAnySet_Check( PyObject *p)

  如果 p 是 `set` 物件、`frozenset` 物件，或是子類別的實例，則回傳 true。此函式總會成功執行。

int PySet_CheckExact( PyObject *p)

  如果 p 是 `set` 物件但不是子類別的實例，則回傳 true。此函式總會成功執行。

  在 3.10 版被加入.

int PyAnySet_CheckExact( PyObject *p)

  如果 p 是 `set` 物件或 `frozenset` 物件但不是子類別的實例，則回傳 true。此函式總會成功執行。

int PyFrozenSet_CheckExact( PyObject *p)

  如果 p 是 `frozenset` 物件但不是子類別的實例，則回傳 true。此函式總會成功執行。

PyObject *PySet_New( PyObject *iterable)
  回傳值：新的參照。 為 穩定 ABI 的一部分. Thread safety: Safe for concurrent use on the same object.

  Return a new `set` containing objects returned by the iterable. The iterable may be `NULL` to create a new empty set. Return the new set on success or `NULL` on failure. Raise `TypeError` if iterable is not actually iterable. The constructor is also useful for copying a set (`c=set(s)`).

  備註

  The operation is atomic on free threading when iterable is a `set`, `frozenset`, `dict` or `frozendict`.

PyObject *PyFrozenSet_New( PyObject *iterable)
  回傳值：新的參照。 為 穩定 ABI 的一部分. Thread safety: Safe for concurrent use on the same object.

  Return a new `frozenset` containing objects returned by the iterable. The iterable may be `NULL` to create a new empty frozenset. Return the new set on success or `NULL` on failure. Raise `TypeError` if iterable is not actually iterable.

  備註

  The operation is atomic on free threading when iterable is a `set`, `frozenset`, `dict` or `frozendict`.

The following functions and macros are available for instances of `set` or `frozenset` or instances of their subtypes.

Py_ssize_t PySet_Size( PyObject *anyset)
  為 穩定 ABI 的一部分. Thread safety: Atomic.

  Return the length of a `set` or `frozenset` object. Equivalent to `len(anyset)`. Raises a `SystemError` if anyset is not a `set`, `frozenset`, or an instance of a subtype.

Py_ssize_t PySet_GET_SIZE( PyObject *anyset)
  Thread safety: Atomic.

  Macro form of `PySet_Size()` without error checking.

int PySet_Contains( PyObject *anyset, PyObject *key)
  為 穩定 ABI 的一部分. Thread safety: Safe for concurrent use on the same object.

  Return `1` if found, `0` if not found, and `-1` if an error is encountered. Unlike the Python `__contains__()` method, this function does not automatically convert unhashable sets into temporary frozensets. Raise a `TypeError` if the key is unhashable. Raise `SystemError` if anyset is not a `set`, `frozenset`, or an instance of a subtype.

  備註

  The operation is atomic on free threading when key is `str`, `int`, `float`, `bool` or `bytes`.

int PySet_Add( PyObject *set, PyObject *key)
  為 穩定 ABI 的一部分. Thread safety: Safe for concurrent use on the same object.

  Add key to a `set` instance. Also works with `frozenset` instances (like `PyTuple_SetItem()` it can be used to fill in the values of brand new frozensets before they are exposed to other code). Return `0` on success or `-1` on failure. Raise a `TypeError` if the key is unhashable. Raise a `MemoryError` if there is no room to grow. Raise a `SystemError` if set is not an instance of `set` or its subtype.

  備註

  The operation is atomic on free threading when key is `str`, `int`, `float`, `bool` or `bytes`.

The following functions are available for instances of `set` or its subtypes but not for instances of `frozenset` or its subtypes.

int PySet_Discard( PyObject *set, PyObject *key)
  為 穩定 ABI 的一部分. Thread safety: Safe for concurrent use on the same object.

  Return `1` if found and removed, `0` if not found (no action taken), and `-1` if an error is encountered. Does not raise `KeyError` for missing keys. Raise a `TypeError` if the key is unhashable. Unlike the Python `discard()` method, this function does not automatically convert unhashable sets into temporary frozensets. Raise `SystemError` if set is not an instance of `set` or its subtype.

  備註

  The operation is atomic on free threading when key is `str`, `int`, `float`, `bool` or `bytes`.

PyObject *PySet_Pop( PyObject *set)
  回傳值：新的參照。 為 穩定 ABI 的一部分. Thread safety: Atomic.

  Return a new reference to an arbitrary object in the set, and removes the object from the set. Return `NULL` on failure. Raise `KeyError` if the set is empty. Raise a `SystemError` if set is not an instance of `set` or its subtype.

int PySet_Clear( PyObject *set)
  為 穩定 ABI 的一部分. Thread safety: Atomic.

  Empty an existing set of all elements. Return `0` on success. Return `-1` and raise `SystemError` if set is not an instance of `set` or its subtype.

  備註

  In the free-threaded build, the set is emptied before its entries are cleared, so other threads will observe an empty set rather than intermediate states.

## 已棄用的 API

PySet_MINSIZE

  A constant representing the size of an internal preallocated table inside `PySetObject` instances.

  這僅為完整性而記錄於文件，且因為無法保證特定版本的 CPython 會使用具有固定大小的預分配表格。在不處理不穩定集合內部結構的程式碼中，`PySet_MINSIZE` 可以替換為像 `8` 這樣的小常數。

  如果要查詢集合的大小，請使用 `PySet_Size()`。

  Soft deprecated since version 3.14.