one good use: a subclass adding a method to express the duration as
a number of hours (or minutes, or whatever else you want to add). The
native breakdown into days+seconds+us is often clumsy. Incidentally
moved a large chunk of object-initialization code closer to the top of
the file, to avoid worse forward-reference trickery.
the itertoolsmodule.
* Taught itertools.repeat(obj, n) to treat negative repeat counts as
zero. This behavior matches that for sequences and prevents
infinite loops.
that was used to start the thread. This is useful to track down the
source of the problem when there is no traceback, as can happen when a
daemon thread gets to run after Python is finialized (a new kind of
event, somehow this is now possible due to changes in Py_Finalize()).
to use LASTMARK_SAVE()/LASTMARK_RESTORE(), based on the discussion
in patch #712900.
- Cleaned up LASTMARK_SAVE()/LASTMARK_RESTORE() usage, based on the
established rules.
- Moved the upper part of the just commited patch (relative to bug #725106)
to outside the for() loop of BRANCH OP. There's no need to mark_save()
in every loop iteration.
This problem is related to a wrong behavior from mark_save/restore(),
which don't restore the mark_stack_base before restoring the marks.
Greg's suggestion was to change the asserts, which happen to be
the only recursive ops that can continue the loop, but the problem would
happen to any operation with the same behavior. So, rather than
hardcoding this into asserts, I have changed mark_save/restore() to
always restore the stackbase before restoring the marks.
Both solutions should fix these two cases, presented by Greg:
>>> re.match('(a)(?:(?=(b)*)c)*', 'abb').groups()
('b', None)
>>> re.match('(a)((?!(b)*))*', 'abb').groups()
('b', None, None)
The rest of the bug and patch in #725149 must be discussed further.
within repeats of alternatives. The only change to the original
patch was to convert the tests to the new test_re.py file.
This patch fixes cases like:
>>> re.match('((a)|b)*', 'abc').groups()
('b', '')
Which is wrong (it's impossible to match the empty string),
and incompatible with other regex systems, like the following
examples show:
% perl -e '"abc" =~ /^((a)|b)*/; print "$1 $2\n";'
b a
% echo "abc" | sed -r -e "s/^((a)|b)*/\1 \2|/"
b a|c
- The socket module now provides the functions inet_pton and inet_ntop
for converting between string and packed representation of IP addresses.
See SF patch #658327.
This still needs a bit of work in the doc area, because it is not
available on all platforms (especially not on Windows).
(contributed by logistix; substantially reworked by rhettinger).
To create a representation of non-string arrays, array_repr() was
starting with a base Python string object and repeatedly using +=
to concatenate the representation of individual objects.
Logistix had the idea to convert to an intermediate tuple form and
then join it all at once. I took advantage of existing tools and
formed a list with array_tolist() and got its representation through
PyObject_Repr(v) which already has a fast implementation for lists.
docs here are best-guess: the MS docs I could find weren't clear, and
some even claimed _commit() has no effect on Win32 systems (which is
easily shown to be false just by trying it).
* UINT_MAX -> ULONG_MAX since we are dealing with longs
* ParseTuple needs &int for 'i' and &long for 'l'
There may be a better way to do this, but this works.
string does what is expected (ie unset [BEGIN|END]LIBPATH)
- set the size of the DosQuerySysInfo buffer correctly; it was safe,
but incorrect (allowing a 1 element overrun)
I've applied a modified version of Greg Chapman's patch. I've included
the fixes without introducing the reorganization mentioned, for the sake
of stability. Also, the second fix mentioned in the patch don't fix the
mentioned problem anymore, because of the change introduced by patch
#720991 (by Greg as well). The new fix wasn't complicated though, and is
included as well.
As a note. It seems that there are other places that require the
"protection" of LASTMARK_SAVE()/LASTMARK_RESTORE(), and are just waiting
for someone to find how to break them. Particularly, I belive that every
recursion of SRE_MATCH() should be protected by these macros. I won't
do that right now since I'm not completely sure about this, and we don't
have much time for testing until the next release.
to be compliant with previous python versions, by backing out the changes
made in revision 2.84 which affected this. The bugfix for backtracking is
still maintained.
New functions:
unsigned long PyInt_AsUnsignedLongMask(PyObject *);
unsigned PY_LONG_LONG) PyInt_AsUnsignedLongLongMask(PyObject *);
unsigned long PyLong_AsUnsignedLongMask(PyObject *);
unsigned PY_LONG_LONG) PyLong_AsUnsignedLongLongMask(PyObject *);
New and changed format codes:
b unsigned char 0..UCHAR_MAX
B unsigned char none **
h unsigned short 0..USHRT_MAX
H unsigned short none **
i int INT_MIN..INT_MAX
I * unsigned int 0..UINT_MAX
l long LONG_MIN..LONG_MAX
k * unsigned long none
L long long LLONG_MIN..LLONG_MAX
K * unsigned long long none
Notes:
* New format codes.
** Changed from previous "range-and-a-half" to "none"; the
range-and-a-half checking wasn't particularly useful.
New test test_getargs2.py, to verify all this.
A small fix for bug #545855 and Greg Chapman's
addition of op code SRE_OP_MIN_REPEAT_ONE for
eliminating recursion on simple uses of pattern '*?' on a
long string.
of PyObject_HasAttr(); the former promises never to execute
arbitrary Python code. Undid many of the changes recently made to
worm around the worst consequences of that PyObject_HasAttr() could
execute arbitrary Python code.
Compatibility is hard to discuss, because the dangerous cases are
so perverse, and much of this appears to rely on implementation
accidents.
To start with, using hasattr() to check for __del__ wasn't only
dangerous, in some cases it was wrong: if an instance of an old-
style class didn't have "__del__" in its instance dict or in any
base class dict, but a getattr hook said __del__ existed, then
hasattr() said "yes, this object has a __del__". But
instance_dealloc() ignores the possibility of getattr hooks when
looking for a __del__, so while object.__del__ succeeds, no
__del__ method is called when the object is deleted. gc was
therefore incorrect in believing that the object had a finalizer.
The new method doesn't suffer that problem (like instance_dealloc(),
_PyObject_Lookup() doesn't believe __del__ exists in that case), but
does suffer a somewhat opposite-- and even more obscure --oddity:
if an instance of an old-style class doesn't have "__del__" in its
instance dict, and a base class does have "__del__" in its dict,
and the first base class with a "__del__" associates it with a
descriptor (an object with a __get__ method), *and* if that
descriptor raises an exception when __get__ is called, then
(a) the current method believes the instance does have a __del__,
but (b) hasattr() does not believe the instance has a __del__.
While these disagree, I believe the new method is "more correct":
because the descriptor *will* be called when the object is
destructed, it can execute arbitrary Python code at the time the
object is destructed, and that's really what gc means by "has a
finalizer": not specifically a __del__ method, but more generally
the possibility of executing arbitrary Python code at object
destruction time. Code in a descriptor's __get__() executed at
destruction time can be just as problematic as code in a
__del__() executed then.
So I believe the new method is better on all counts.
Bugfix candidate, but it's unclear to me how all this differs in
the 2.2 branch (e.g., new-style and old-style classes already
took different gc paths in 2.3 before this last round of patches,
but don't in the 2.2 branch).
instead of looping. Smaller and clearer. Faster, too, when we're not
appending to gc.garbage: gc_list_merge() takes constant time, regardless
of the lists' sizes.
append_objects(): Moved up to live with the other list manipulation
utilities.
externally unreachable objects with finalizers, and externally unreachable
objects without finalizers reachable from such objects. This allows us
to call has_finalizer() at most once per object, and so limit the pain of
nasty getattr hooks. This fixes the failing "boom 2" example Jeremy
posted (a non-printing variant of which is now part of test_gc), via never
triggering the nasty part of its __getattr__ method.
to special-case classic classes, or to worry about refcounts;
has_finalizer() deleted the current object iff the first entry in
the unreachable list has changed. I don't believe it was correct
to check for ob_refcnt == 1, either: the dealloc routine would get
called by Py_DECREF then, but there's nothing to stop the dealloc
routine from ressurecting the object, and then gc would remain at
the head of the unreachable list despite that its refcount temporarily
fell to 0 (and that would lead to an infinite loop in move_finalizers()).
I'm still worried about has_finalizer() resurrecting other objects
in the unreachable list: what's to stop them from getting collected?
delstr from initgc() into collect(). initgc() isn't called unless the
user explicitly imports gc, so can be used only for initialization of
user-visible module features; delstr needs to be initialized for proper
internal operation, whether or not gc is explicitly imported.
Bugfix candidate? I don't know whether the new bug was backported to
2.2 already.
Martin v. Löwis
Walter Dörwald
Tim Peters
Gregory P. Smith
Michael W. Hudson
Just van Rossum
Skip Montanaro
Raymond Hettinger
Anthony Baxter
Andrew M. Kuchling
Guido van Rossum
Gustavo Niemeyer
Thomas Heller
Barry Warsaw
Mark Hammond
Neal Norwitz
Andrew MacIntyre
Jeremy Hylton
Greg Ward