STINNER Victor added the comment:
> __len__() always returns an int which on windows machines is tied to the size
> of a c long and is always 32 bits even if it's compiled for 64 bit.
Hum, I don't understand this statement. It looks like the code uses Py_ssize_t
everywhere and Py_ssize_t is supposed to be able to store a whole pointer, so
be 64-bit when Python is compiled in 64-bit mode.
> Python 2.7.8 |Anaconda 2.1.0 (64-bit)| (default, Jul 2 2014, 15:12:11) [MSC
> v.1500 64 bit (AMD64)] on win32
This is a 32-bit build ("win32"), no? max.size is 2147483647 on 32-bit mode if
I recall correctly. On 64-bit, it's 9223372036854775807. By the way, on 64-bit,
sys.maxsize == sys.maxint.
In Python 2:
len(obj) => builtin_len() => PyObject_Size() which returns a Py_ssize_t
For string, PyObject_Size() => string_length() => Py_SIZE(obj) => ((PyVarObject
*)obj)->ob_size
PyVarObject.ob_size has the type Py_ssize_t.
builtin_len() gets a Py_ssize_t which is converted to a Python int or long with
PyInt_FromSsize_t().
PyInt_FromSsize_t() creates an int if the value fits into a C long, or it calls
_PyLong_FromSsize_t().
Difference in Python 3:
builtin_len() also gets a Py_ssize_t, but it calls PyLong_FromSsize_t() (since
Python short integers as gone, long became int in Python 3).
string_length() is replaced with unicode_length() => PyUnicode_GET_LENGTH() =>
(PyASCIIObject *)obj)->length and PyASCIIObject.length type is Py_ssize_t.
----------
nosy: +haypo
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