You can't replace a value in a tuple, but you can modify it, e.g.,
>>> x = (1, 2, [3])
>>> x
(1, 2, [3])
>>> x[2].append(4)
>>> x
(1, 2, [3, 4]) >>> x = (1, 2, [3])
>>> x
(1, 2, [3])
>>> x[2].append(4)
>>> x
(1, 2, [3, 4]) import ctypes
def tuple_setitem(t, index, item):
obj = ctypes.py_object(t)
item = ctypes.py_object(item)
ref_count = ctypes.c_long.from_address(id(t))
original_count = ref_count.value
if original_count != 1:
ref_count.value = 1
ctypes.pythonapi.Py_IncRef(item)
ctypes.pythonapi.PyTuple_SetItem(obj, ctypes.c_ssize_t(index), item)
ref_count.value = original_count
>>> x = (1, 2, 3,)
>>> tuple_setitem(x, 1, "foo")
>>> x
(1, "foo", 3)
What you did was modify the underlying list, the tuple itself is immutable.
If it has mutable items in it, yes. But in that case, the tuple can't be used as a dictionary key; Python checks, not just that the tuple itself is immutable, but that every object in it is immutable.