diff options
| -rw-r--r-- | Doc/library/functions.rst | 34 | ||||
| -rw-r--r-- | Lib/test/test_builtin.py | 28 | ||||
| -rw-r--r-- | Misc/NEWS | 4 | ||||
| -rw-r--r-- | Python/bltinmodule.c | 40 |
4 files changed, 78 insertions, 28 deletions
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst index 43164af..3d239ec 100644 --- a/Doc/library/functions.rst +++ b/Doc/library/functions.rst @@ -753,19 +753,22 @@ are always available. They are listed here in alphabetical order. already arranged into argument tuples, see :func:`itertools.starmap`\. -.. function:: max(iterable, *[, key]) +.. function:: max(iterable, *[, default, key]) max(arg1, arg2, *args[, key]) Return the largest item in an iterable or the largest of two or more arguments. - If one positional argument is provided, *iterable* must be a non-empty - iterable (such as a non-empty string, tuple or list). The largest item - in the iterable is returned. If two or more positional arguments are - provided, the largest of the positional arguments is returned. + If one positional argument is provided, it should be an :term:`iterable`. + The largest item in the iterable is returned. If two or more positional + arguments are provided, the smallest of the positional arguments is + returned. - The optional keyword-only *key* argument specifies a one-argument ordering - function like that used for :meth:`list.sort`. + There are two optional keyword-only arguments. The *key* argument specifies + a one-argument ordering function like that used for :meth:`list.sort`. The + *default* argument specifies an object to return if the provided iterable is + empty. If the iterable is empty and *default* is not provided, a + :exc:`ValueError` is raised. If multiple items are maximal, the function returns the first one encountered. This is consistent with other sort-stability preserving tools @@ -781,19 +784,22 @@ are always available. They are listed here in alphabetical order. :ref:`typememoryview` for more information. -.. function:: min(iterable, *[, key]) +.. function:: min(iterable, *[, default, key]) min(arg1, arg2, *args[, key]) Return the smallest item in an iterable or the smallest of two or more arguments. - If one positional argument is provided, *iterable* must be a non-empty - iterable (such as a non-empty string, tuple or list). The smallest item - in the iterable is returned. If two or more positional arguments are - provided, the smallest of the positional arguments is returned. + If one positional argument is provided, it should be an :term:`iterable`. + The smallest item in the iterable is returned. If two or more positional + arguments are provided, the smallest of the positional arguments is + returned. - The optional keyword-only *key* argument specifies a one-argument ordering - function like that used for :meth:`list.sort`. + There are two optional keyword-only arguments. The *key* argument specifies + a one-argument ordering function like that used for :meth:`list.sort`. The + *default* argument specifies an object to return if the provided iterable is + empty. If the iterable is empty and *default* is not provided, a + :exc:`ValueError` is raised. If multiple items are minimal, the function returns the first one encountered. This is consistent with other sort-stability preserving tools diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py index f850456..acbc29c 100644 --- a/Lib/test/test_builtin.py +++ b/Lib/test/test_builtin.py @@ -847,8 +847,19 @@ class BuiltinTest(unittest.TestCase): self.assertEqual(max(1, 2.0, 3), 3) self.assertEqual(max(1.0, 2, 3), 3) + self.assertRaises(TypeError, max) + self.assertRaises(TypeError, max, 42) + self.assertRaises(ValueError, max, ()) + class BadSeq: + def __getitem__(self, index): + raise ValueError + self.assertRaises(ValueError, max, BadSeq()) + for stmt in ( "max(key=int)", # no args + "max(default=None)", + "max(1, 2, default=None)", # require container for default + "max(default=None, key=int)", "max(1, key=int)", # single arg not iterable "max(1, 2, keystone=int)", # wrong keyword "max(1, 2, key=int, abc=int)", # two many keywords @@ -865,6 +876,13 @@ class BuiltinTest(unittest.TestCase): self.assertEqual(max((1,2), key=neg), 1) # two elem iterable self.assertEqual(max(1, 2, key=neg), 1) # two elems + self.assertEqual(max((), default=None), None) # zero elem iterable + self.assertEqual(max((1,), default=None), 1) # one elem iterable + self.assertEqual(max((1,2), default=None), 2) # two elem iterable + + self.assertEqual(max((), default=1, key=neg), 1) + self.assertEqual(max((1, 2), default=3, key=neg), 1) + data = [random.randrange(200) for i in range(100)] keys = dict((elem, random.randrange(50)) for elem in data) f = keys.__getitem__ @@ -891,6 +909,9 @@ class BuiltinTest(unittest.TestCase): for stmt in ( "min(key=int)", # no args + "min(default=None)", + "min(1, 2, default=None)", # require container for default + "min(default=None, key=int)", "min(1, key=int)", # single arg not iterable "min(1, 2, keystone=int)", # wrong keyword "min(1, 2, key=int, abc=int)", # two many keywords @@ -907,6 +928,13 @@ class BuiltinTest(unittest.TestCase): self.assertEqual(min((1,2), key=neg), 2) # two elem iterable self.assertEqual(min(1, 2, key=neg), 2) # two elems + self.assertEqual(min((), default=None), None) # zero elem iterable + self.assertEqual(min((1,), default=None), 1) # one elem iterable + self.assertEqual(min((1,2), default=None), 1) # two elem iterable + + self.assertEqual(min((), default=1, key=neg), 1) + self.assertEqual(min((1, 2), default=1, key=neg), 2) + data = [random.randrange(200) for i in range(100)] keys = dict((elem, random.randrange(50)) for elem in data) f = keys.__getitem__ @@ -13,6 +13,10 @@ Core and Builtins - Issue #18184: PyUnicode_FromFormat() and PyUnicode_FromFormatV() now raise OverflowError when an argument of %c format is out of range. +- Issue #18111: The min() and max() functions now support a default argument + to be returned instead of raising a ValueError on an empty sequence. + (Contributed by Julian Berman.) + - Issue #18137: Detect integer overflow on precision in float.__format__() and complex.__format__(). diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c index 356bb50..86e0805 100644 --- a/Python/bltinmodule.c +++ b/Python/bltinmodule.c @@ -1329,26 +1329,35 @@ static PyObject * min_max(PyObject *args, PyObject *kwds, int op) { PyObject *v, *it, *item, *val, *maxitem, *maxval, *keyfunc=NULL; + PyObject *emptytuple, *defaultval = NULL; + static char *kwlist[] = {"key", "default", NULL}; const char *name = op == Py_LT ? "min" : "max"; + const int positional = PyTuple_Size(args) > 1; + int ret; - if (PyTuple_Size(args) > 1) + if (positional) v = args; else if (!PyArg_UnpackTuple(args, (char *)name, 1, 1, &v)) return NULL; - if (kwds != NULL && PyDict_Check(kwds) && PyDict_Size(kwds)) { - keyfunc = PyDict_GetItemString(kwds, "key"); - if (PyDict_Size(kwds)!=1 || keyfunc == NULL) { - PyErr_Format(PyExc_TypeError, - "%s() got an unexpected keyword argument", name); - return NULL; - } - Py_INCREF(keyfunc); + emptytuple = PyTuple_New(0); + if (emptytuple == NULL) + return NULL; + ret = PyArg_ParseTupleAndKeywords(emptytuple, kwds, "|$OO", kwlist, + &keyfunc, &defaultval); + Py_DECREF(emptytuple); + if (!ret) + return NULL; + + if (positional && defaultval != NULL) { + PyErr_Format(PyExc_TypeError, + "Cannot specify a default for %s() with multiple " + "positional arguments", name); + return NULL; } it = PyObject_GetIter(v); if (it == NULL) { - Py_XDECREF(keyfunc); return NULL; } @@ -1392,14 +1401,18 @@ min_max(PyObject *args, PyObject *kwds, int op) if (PyErr_Occurred()) goto Fail_it; if (maxval == NULL) { - PyErr_Format(PyExc_ValueError, - "%s() arg is an empty sequence", name); assert(maxitem == NULL); + if (defaultval != NULL) { + Py_INCREF(defaultval); + maxitem = defaultval; + } else { + PyErr_Format(PyExc_ValueError, + "%s() arg is an empty sequence", name); + } } else Py_DECREF(maxval); Py_DECREF(it); - Py_XDECREF(keyfunc); return maxitem; Fail_it_item_and_val: @@ -1410,7 +1423,6 @@ Fail_it: Py_XDECREF(maxval); Py_XDECREF(maxitem); Py_DECREF(it); - Py_XDECREF(keyfunc); return NULL; } |