# List Objects

type PyListObject

  This subtype of `PyObject` represents a Python list object.

PyTypeObject PyList_Type
  Parte del ABI Stabile.

  This instance of `PyTypeObject` represents the Python list type. This is the same object as `list` in the Python layer.

int PyList_Check(PyObject *p)
  Thread safety: Atomic.

  Return true if p is a list object or an instance of a subtype of the list type. This function always succeeds.

int PyList_CheckExact(PyObject *p)
  Thread safety: Atomic.

  Return true if p is a list object, but not an instance of a subtype of the list type. This function always succeeds.

PyObject *PyList_New(Py_ssize_t len)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile. Thread safety: Atomic.

  Return a new list of length len on success, or `NULL` on failure.

  Nota

  If len is greater than zero, the returned list object’s items are set to `NULL`. Thus you cannot use abstract API functions such as `PySequence_SetItem()` or expose the object to Python code before setting all items to a real object with `PyList_SetItem()` or `PyList_SET_ITEM()`. The following APIs are safe APIs before the list is fully initialized: `PyList_SetItem()` and `PyList_SET_ITEM()`.

Py_ssize_t PyList_Size(PyObject *list)
  Parte del ABI Stabile. Thread safety: Atomic.

  Return the length of the list object in list; this is equivalent to `len(list)` on a list object.

Py_ssize_t PyList_GET_SIZE(PyObject *list)
  Thread safety: Atomic.

  Similar to `PyList_Size()`, but without error checking.

PyObject *PyList_GetItemRef(PyObject *list, Py_ssize_t index)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile dalla versione 3.13. Thread safety: Atomic.

  Return the object at position index in the list pointed to by list. The position must be non-negative; indexing from the end of the list is not supported. If index is out of bounds (`<0 or >=len(list)`), return `NULL` and set an `IndexError` exception.

  Added in version 3.13.

PyObject *PyList_GetItem(PyObject *list, Py_ssize_t index)
  Valore di ritorno: Riferimento preso in prestito. Parte del ABI Stabile. Thread safety: Safe to call from multiple threads with external synchronization only.

  Like `PyList_GetItemRef()`, but returns a borrowed reference instead of a strong reference.

  Nota

  In the free-threaded build, the returned borrowed reference may become invalid if another thread modifies the list concurrently. Prefer `PyList_GetItemRef()`, which returns a strong reference.

PyObject *PyList_GET_ITEM(PyObject *list, Py_ssize_t i)
  Valore di ritorno: Riferimento preso in prestito. Thread safety: Safe to call from multiple threads with external synchronization only.

  Similar to `PyList_GetItem()`, but without error checking.

  Nota

  In the free-threaded build, the returned borrowed reference may become invalid if another thread modifies the list concurrently. Prefer `PyList_GetItemRef()`, which returns a strong reference.

int PyList_SetItem(PyObject *list, Py_ssize_t index, PyObject *item)
  Parte del ABI Stabile. Thread safety: Atomic.

  Set the item at index index in list to item. Return `0` on success. If index is out of bounds, return `-1` and set an `IndexError` exception.

  Nota

  This function «steals» a reference to item and discards a reference to an item already in the list at the affected position.

void PyList_SET_ITEM(PyObject *list, Py_ssize_t i, PyObject *o)
  Thread safety: Safe to call from multiple threads with external synchronization only.

  Macro form of `PyList_SetItem()` without error checking. This is normally only used to fill in new lists where there is no previous content.

  Bounds checking is performed as an assertion if Python is built in debug mode or `with assertions`.

  Nota

  This macro «steals» a reference to item, and, unlike `PyList_SetItem()`, does not discard a reference to any item that is being replaced; any reference in list at position i will be leaked.

  Nota

  In the free-threaded build, this macro has no internal synchronization. It is normally only used to fill in new lists where no other thread has a reference to the list. If the list may be shared, use `PyList_SetItem()` instead, which uses a per-object lock.

int PyList_Insert(PyObject *list, Py_ssize_t index, PyObject *item)
  Parte del ABI Stabile. Thread safety: Safe for concurrent use on the same object.

  Insert the item item into list list in front of index index. Return `0` if successful; return `-1` and set an exception if unsuccessful. Analogous to `list.insert(index, item)`.

int PyList_Append(PyObject *list, PyObject *item)
  Parte del ABI Stabile. Thread safety: Atomic.

  Append the object item at the end of list list. Return `0` if successful; return `-1` and set an exception if unsuccessful. Analogous to `list.append(item)`.

PyObject *PyList_GetSlice(PyObject *list, Py_ssize_t low, Py_ssize_t high)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile. Thread safety: Atomic.

  Return a list of the objects in list containing the objects between low and high. Return `NULL` and set an exception if unsuccessful. Analogous to `list[low:high]`. Indexing from the end of the list is not supported.

int PyList_SetSlice(PyObject *list, Py_ssize_t low, Py_ssize_t high, PyObject *itemlist)
  Parte del ABI Stabile. Thread safety: Safe for concurrent use on the same object.

  Set the slice of list between low and high to the contents of itemlist. Analogous to `list[low:high] = itemlist`. The itemlist may be `NULL`, indicating the assignment of an empty list (slice deletion). Return `0` on success, `-1` on failure. Indexing from the end of the list is not supported.

  Nota

  In the free-threaded build, when itemlist is a `list`, both list and itemlist are locked for the duration of the operation. For other iterables (or `NULL`), only list is locked.

int PyList_Extend(PyObject *list, PyObject *iterable)
  Thread safety: Safe for concurrent use on the same object.

  Extend list with the contents of iterable. This is the same as `PyList_SetSlice(list, PY_SSIZE_T_MAX, PY_SSIZE_T_MAX, iterable)` and analogous to `list.extend(iterable)` or `list += iterable`.

  Raise an exception and return `-1` if list is not a `list` object. Return 0 on success.

  Added in version 3.13.

  Nota

  In the free-threaded build, when iterable is a `list`, `set`, `dict`, or dict view, both list and iterable (or its underlying dict) are locked for the duration of the operation. For other iterables, only list is locked; iterable may be concurrently modified by another thread.

int PyList_Clear(PyObject *list)
  Thread safety: Atomic.

  Remove all items from list. This is the same as `PyList_SetSlice(list, 0, PY_SSIZE_T_MAX, NULL)` and analogous to `list.clear()` or `del list[:]`.

  Raise an exception and return `-1` if list is not a `list` object. Return 0 on success.

  Added in version 3.13.

int PyList_Sort(PyObject *list)
  Parte del ABI Stabile. Thread safety: Safe for concurrent use on the same object.

  Sort the items of list in place. Return `0` on success, `-1` on failure. This is equivalent to `list.sort()`.

  Nota

  In the free-threaded build, element comparison via `__lt__()` can execute arbitrary Python code, during which the per-object lock may be temporarily released. For built-in types (`str`, `int`, `float`), the lock is not released during comparison.

int PyList_Reverse(PyObject *list)
  Parte del ABI Stabile. Thread safety: Safe for concurrent use on the same object.

  Reverse the items of list in place. Return `0` on success, `-1` on failure. This is the equivalent of `list.reverse()`.

PyObject *PyList_AsTuple(PyObject *list)
  Valore di ritorno: Nuovo riferimento. Parte del ABI Stabile. Thread safety: Atomic.

  Return a new tuple object containing the contents of list; equivalent to `tuple(list)`.