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| author | Raymond Hettinger <python@rcn.com> | 2003-05-02 19:44:20 (GMT) |
|---|---|---|
| committer | Raymond Hettinger <python@rcn.com> | 2003-05-02 19:44:20 (GMT) |
| commit | 341deb74e7ec78eaf99838669ce04871e9f15783 (patch) | |
| tree | c3c8257703ef5e718c8f850945dc2e7070f25071 | |
| parent | 14ef54cd833c7ccfa0b3d03e2b45074d54a8ac87 (diff) | |
| download | cpython-341deb74e7ec78eaf99838669ce04871e9f15783.zip cpython-341deb74e7ec78eaf99838669ce04871e9f15783.tar.gz cpython-341deb74e7ec78eaf99838669ce04871e9f15783.tar.bz2 | |
The previous made the stop argument optional.
It is better to be explicit and just allow stop to be None.
| -rw-r--r-- | Doc/lib/libitertools.tex | 17 | ||||
| -rw-r--r-- | Lib/test/test_itertools.py | 2 | ||||
| -rw-r--r-- | Modules/itertoolsmodule.c | 4 |
3 files changed, 10 insertions, 13 deletions
diff --git a/Doc/lib/libitertools.tex b/Doc/lib/libitertools.tex index d0e1269..f291fe3 100644 --- a/Doc/lib/libitertools.tex +++ b/Doc/lib/libitertools.tex @@ -197,9 +197,9 @@ by functions or loops that truncate the stream. If \var{start} is non-zero, then elements from the iterable are skipped until start is reached. Afterward, elements are returned consecutively unless \var{step} is set higher than one which results in items being - skipped. If \var{stop} is not specified or is \code{None}, then iteration - continues indefinitely; otherwise, it stops at the specified position. - Unlike regular slicing, + skipped. If \var{stop} is \code{None}, then iteration continues until + the iterator is exhausted, if at all; otherwise, it stops at the specified + position. Unlike regular slicing, \function{islice()} does not support negative values for \var{start}, \var{stop}, or \var{step}. Can be used to extract related fields from data where the internal structure has been flattened (for @@ -208,13 +208,10 @@ by functions or loops that truncate the stream. \begin{verbatim} def islice(iterable, *args): - if args: - s = slice(*args) - next = s.start or 0 - stop = s.stop - step = s.step or 1 - else: - next, stop, step = 0, None, 1 + s = slice(*args) + next = s.start or 0 + stop = s.stop + step = s.step or 1 for cnt, element in enumerate(iterable): if cnt < next: continue diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py index d0b1ce8..ef2ab26 100644 --- a/Lib/test/test_itertools.py +++ b/Lib/test/test_itertools.py @@ -78,12 +78,12 @@ class TestBasicOps(unittest.TestCase): self.assertEqual(list(islice(xrange(100), *args)), range(*tgtargs)) # Test stop=None - self.assertEqual(list(islice(xrange(10))), range(10)) self.assertEqual(list(islice(xrange(10), None)), range(10)) self.assertEqual(list(islice(xrange(10), 2, None)), range(2, 10)) self.assertEqual(list(islice(xrange(10), 1, None, 2)), range(1, 10, 2)) # Test invalid arguments + self.assertRaises(TypeError, islice, xrange(10)) self.assertRaises(TypeError, islice, xrange(10), 1, 2, 3, 4) self.assertRaises(ValueError, islice, xrange(10), -5, 10, 1) self.assertRaises(ValueError, islice, xrange(10), 1, -5, -1) diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c index f05ebd6..2d496b5 100644 --- a/Modules/itertoolsmodule.c +++ b/Modules/itertoolsmodule.c @@ -477,7 +477,7 @@ islice_new(PyTypeObject *type, PyObject *args, PyObject *kwds) isliceobject *lz; numargs = PyTuple_Size(args); - if (!PyArg_ParseTuple(args, "O|OOl:islice", &seq, &a1, &a2, &step)) + if (!PyArg_ParseTuple(args, "OO|Ol:islice", &seq, &a1, &a2, &step)) return NULL; if (numargs == 2) { @@ -491,7 +491,7 @@ islice_new(PyTypeObject *type, PyObject *args, PyObject *kwds) return NULL; } } - } else if (numargs == 3 || numargs == 4) { + } else { start = PyInt_AsLong(a1); if (start == -1 && PyErr_Occurred()) { PyErr_Clear(); |