mirror of https://github.com/python/cpython
Issue #16148: Small improvements and cleanup. Added version information
to docs.
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@ -349,6 +349,8 @@ is considered sufficient for this determination.
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returning the default value. On error ``-1`` is returned. This is the
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equivalent to the Python expression ``operator.length_hint(o, default)``.
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.. versionadded:: 3.4
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.. c:function:: PyObject* PyObject_GetItem(PyObject *o, PyObject *key)
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Return element of *o* corresponding to the object *key* or *NULL* on failure.
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@ -241,6 +241,8 @@ their character equivalents.
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actual length, then an estimate using ``__length_hint__``, and finally
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returning the default value.
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.. versionadded:: 3.4
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The :mod:`operator` module also defines tools for generalized attribute and item
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lookups. These are useful for making fast field extractors as arguments for
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:func:`map`, :func:`sorted`, :meth:`itertools.groupby`, or other functions that
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@ -1805,6 +1805,15 @@ through the container; for mappings, :meth:`__iter__` should be the same as
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considered to be false in a Boolean context.
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.. method:: object.__length_hint__(self)
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Called to implement ``operator.length_hint``. Should return an estimated
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length for the object (which may be greater or less than the actual length).
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The length must be an integer ``>=`` 0. This method is purely an
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optimization and is never required for correctness.
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.. versionadded:: 3.4
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.. note::
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Slicing is done exclusively with the following three methods. A call like ::
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@ -403,7 +403,9 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
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PyAPI_FUNC(Py_ssize_t) PyObject_Length(PyObject *o);
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#define PyObject_Length PyObject_Size
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PyAPI_FUNC(int) _PyObject_HasLen(PyObject *o);
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#ifndef Py_LIMITED_API
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PyAPI_FUNC(int) _PyObject_HasLen(PyObject *o);
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#endif
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PyAPI_FUNC(Py_ssize_t) PyObject_LengthHint(PyObject *o, Py_ssize_t);
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/*
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@ -170,7 +170,6 @@ class TestReversed(unittest.TestCase, PickleTest):
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self.assertEqual(type(reversed(x)), type(iter(x)))
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def test_len(self):
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# This is an implementation detail, not an interface requirement
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for s in ('hello', tuple('hello'), list('hello'), range(5)):
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self.assertEqual(operator.length_hint(reversed(s)), len(s))
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r = reversed(s)
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@ -71,8 +71,9 @@ _PyObject_HasLen(PyObject *o) {
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}
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/* The length hint function returns a non-negative value from o.__len__()
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or o.__length_hint__(). If those methods aren't found. If one of the calls
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fails this function returns -1.
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or o.__length_hint__(). If those methods aren't found the defaultvalue is
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returned. If one of the calls fails with an exception other than TypeError
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this function returns -1.
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*/
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Py_ssize_t
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@ -112,21 +113,21 @@ PyObject_LengthHint(PyObject *o, Py_ssize_t defaultvalue)
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return defaultvalue;
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}
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if (!PyLong_Check(result)) {
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PyErr_Format(PyExc_TypeError, "Length hint must be an integer, not %s",
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PyErr_Format(PyExc_TypeError, "__length_hint__ must be an integer, not %.100s",
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Py_TYPE(result)->tp_name);
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Py_DECREF(result);
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return -1;
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}
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defaultvalue = PyLong_AsSsize_t(result);
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res = PyLong_AsSsize_t(result);
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Py_DECREF(result);
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if (defaultvalue < 0 && PyErr_Occurred()) {
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if (res < 0 && PyErr_Occurred()) {
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return -1;
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}
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if (defaultvalue < 0) {
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if (res < 0) {
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PyErr_Format(PyExc_ValueError, "__length_hint__() should return >= 0");
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return -1;
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}
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return defaultvalue;
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return res;
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}
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PyObject *
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