traverseda
/
cpython
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Bug #1520864 (again): unpacking singleton tuples in list comprehensions and 

generator expressions (x for x, in ... ) works again.

Sigh, I only fixed for loops the first time, not list comps and genexprs too.
I couldn't find any more unpacking cases where there is a similar bug lurking.

This code should be refactored to eliminate the duplication.  I'm sure
the listcomp/genexpr code can be refactored.  I'm not sure if the for loop
can re-use any of the same code though.

Will backport to 2.5 (the only place it matters).
This commit is contained in:
Neal Norwitz 2006-09-05 03:53:08 +00:00
parent 4bc2c0919b
commit dac090d3e6
4 changed files with 23 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Lib/test/test_grammar.py
View File

@ -825,6 +825,10 @@ verify([(i,j) for i in range(10) for j in range(5)] == list(g))
verify([ x for x in range(10) if x % 2 if x % 3 ], [1, 5, 7])
verify((x for x in range(10) if x % 2 if x % 3), [1, 5, 7])
# Verify unpacking single element tuples in listcomp/genexp.
vereq([x for x, in [(4,), (5,), (6,)]], [4, 5, 6])
vereq(list(x for x, in [(7,), (8,), (9,)]), [7, 8, 9])
# Test ifelse expressions in various cases
def _checkeval(msg, ret):
"helper to check that evaluation of expressions is done correctly"

5
Misc/NEWS
View File

@ -22,6 +22,11 @@ Core and builtins
- The return tuple from str.rpartition(sep) is (tail, sep, head) where
head is the original string if sep was not found.
- Bug #1520864: unpacking singleton tuples in list comprehensions and
generator expressions (x for x, in ... ) works again. Fixing this problem
required changing the .pyc magic number. This means that .pyc files
generated before 2.5c2 will be regenerated.
Library
-------

16
Python/ast.c
View File

@ -983,17 +983,21 @@ ast_for_listcomp(struct compiling *c, const node *n)
comprehension_ty lc;
asdl_seq *t;
expr_ty expression;
node *for_ch;
REQ(ch, list_for);
t = ast_for_exprlist(c, CHILD(ch, 1), Store);
for_ch = CHILD(ch, 1);
t = ast_for_exprlist(c, for_ch, Store);
if (!t)
return NULL;
expression = ast_for_testlist(c, CHILD(ch, 3));
if (!expression)
return NULL;
if (asdl_seq_LEN(t) == 1)
/* Check the # of children rather than the length of t, since
[x for x, in ... ] has 1 element in t, but still requires a Tuple. */
if (NCH(for_ch) == 1)
lc = comprehension((expr_ty)asdl_seq_GET(t, 0), expression, NULL,
c->c_arena);
else
@ -1129,17 +1133,21 @@ ast_for_genexp(struct compiling *c, const node *n)
comprehension_ty ge;
asdl_seq *t;
expr_ty expression;
node *for_ch;
REQ(ch, gen_for);
t = ast_for_exprlist(c, CHILD(ch, 1), Store);
for_ch = CHILD(ch, 1);
t = ast_for_exprlist(c, for_ch, Store);
if (!t)
return NULL;
expression = ast_for_expr(c, CHILD(ch, 3));
if (!expression)
return NULL;
if (asdl_seq_LEN(t) == 1)
/* Check the # of children rather than the length of t, since
(x for x, in ...) has 1 element in t, but still requires a Tuple. */
if (NCH(for_ch) == 1)
ge = comprehension((expr_ty)asdl_seq_GET(t, 0), expression,
NULL, c->c_arena);
else

3
Python/import.c
View File

@ -64,9 +64,10 @@ extern time_t PyOS_GetLastModificationTime(char *, FILE *);
Python 2.5b3: 62111 (fix wrong code: x += yield)
Python 2.5c1: 62121 (fix wrong lnotab with for loops and
storing constants that should have been removed)
Python 2.5c2: 62131 (fix wrong code: for x, in ... in listcomp/genexp)
.
*/
#define MAGIC (62121 | ((long)'\r'<<16) | ((long)'\n'<<24))
#define MAGIC (62131 | ((long)'\r'<<16) | ((long)'\n'<<24))
/* Magic word as global; note that _PyImport_Init() can change the
value of this global to accommodate for alterations of how the