[Python-checkins] cpython: #23949: Improve tuple unpacking error messages.

Wed Apr 15 23:09:10 CEST 2015

https://hg.python.org/cpython/rev/e55cc0834e9c
changeset: 95680:e55cc0834e9c
user: R David Murray <rdmurray at bitdance.com>
date: Wed Apr 15 17:08:45 2015 -0400
summary:
 #23949: Improve tuple unpacking error messages.
Patch by Arnon Yaari.
files:
 Lib/test/test_unpack.py | 2 +-
 Lib/test/test_unpack_ex.py | 9 ++++++++-
 Python/ceval.c | 24 +++++++++++++++++-------
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/Lib/test/test_unpack.py b/Lib/test/test_unpack.py
--- a/Lib/test/test_unpack.py
+++ b/Lib/test/test_unpack.py
@@ -76,7 +76,7 @@
 >>> a, b, c, d = Seq()
 Traceback (most recent call last):
 ...
- ValueError: need more than 3 values to unpack
+ ValueError: not enough values to unpack (expected 4, got 3)
 
 Unpacking sequence too long
 
diff --git a/Lib/test/test_unpack_ex.py b/Lib/test/test_unpack_ex.py
--- a/Lib/test/test_unpack_ex.py
+++ b/Lib/test/test_unpack_ex.py
@@ -85,7 +85,14 @@
 >>> a, *b, c, d, e = Seq()
 Traceback (most recent call last):
 ...
- ValueError: need more than 3 values to unpack
+ ValueError: not enough values to unpack (expected at least 4, got 3)
+
+Unpacking sequence too short and target appears last
+
+ >>> a, b, c, d, *e = Seq()
+ Traceback (most recent call last):
+ ...
+ ValueError: not enough values to unpack (expected at least 4, got 3)
 
 Unpacking a sequence where the test for too long raises a different kind of
 error
diff --git a/Python/ceval.c b/Python/ceval.c
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -3825,9 +3825,17 @@
 if (w == NULL) {
 /* Iterator done, via error or exhaustion. */
 if (!PyErr_Occurred()) {
- PyErr_Format(PyExc_ValueError,
- "need more than %d value%s to unpack",
- i, i == 1 ? "" : "s");
+ if (argcntafter == -1) {
+ PyErr_Format(PyExc_ValueError,
+ "not enough values to unpack (expected %d, got %d)",
+ argcnt, i);
+ }
+ else {
+ PyErr_Format(PyExc_ValueError,
+ "not enough values to unpack "
+ "(expected at least %d, got %d)",
+ argcnt + argcntafter, i);
+ }
 }
 goto Error;
 }
@@ -3844,8 +3852,9 @@
 return 1;
 }
 Py_DECREF(w);
- PyErr_Format(PyExc_ValueError, "too many values to unpack "
- "(expected %d)", argcnt);
+ PyErr_Format(PyExc_ValueError,
+ "too many values to unpack (expected %d)",
+ argcnt);
 goto Error;
 }
 
@@ -3857,8 +3866,9 @@
 
 ll = PyList_GET_SIZE(l);
 if (ll < argcntafter) {
- PyErr_Format(PyExc_ValueError, "need more than %zd values to unpack",
- argcnt + ll);
+ PyErr_Format(PyExc_ValueError,
+ "not enough values to unpack (expected at least %d, got %zd)",
+ argcnt + argcntafter, argcnt + ll);
 goto Error;
 }
 
-- 
Repository URL: https://hg.python.org/cpython
