Added XXX comment about why the undocumented PyRange_New() API function
is too broken to be worth the considerable pain of repairing.
Changed range_new() to stop using PyRange_New(). This fixes a variety
of bogus errors. Nothing in the core uses PyRange_New() now.
Documented that xrange() is intended to be simple and fast, and that
CPython restricts its arguments, and length of its result sequence, to
native C longs.
Added some tests that failed before the patch, and repaired a test that
relied on a bogus OverflowError getting raised.
hack: it would resize *interned* strings in-place! This occurred because
their reference counts do not have their expected value -- stringobject.c
hacks them. Mea culpa.
interning were not clear here -- a subclass could be mutable, for
example -- and had bugs. Explicitly interning a subclass of string
via intern() will raise a TypeError. Internal operations that attempt
to intern a string subclass will have no effect.
Added a few tests to test_builtin that includes the old buggy code and
verifies that calls like PyObject_SetAttr() don't fail. Perhaps these
tests should have gone in test_string.
unicodedata.east_asian_width(). You can still implement your own
simple width() function using it like this:
def width(u):
w = 0
for c in unicodedata.normalize('NFC', u):
cwidth = unicodedata.east_asian_width(c)
if cwidth in ('W', 'F'): w += 2
else: w += 1
return w
the case of __del__ resurrecting an object.
This makes the apparent reference leaks in test_descr go away (which I
expected) and also kills off those in test_gc (which is more surprising
but less so once you actually think about it a bit).
comma expression in listpop() that was being returned. Still essentially
unused (as it is meant to be), but now the compiler thinks it is worth
*something* by having it incremented.
of no more than 8 elements cannot fail.
listpop(): Take advantage of that its calls to list_resize() and
list_ass_slice() can't fail. This is assert'ed in a debug build now, but
in an icky way. That is, you can't say:
assert(some_call() >= 0);
because then some_call() won't occur at all in a release build. So it
has to be a big pile of #ifdefs on Py_DEBUG (yuck), or the pleasant:
status = some_call();
assert(status >= 0);
But in that case, compilers may whine in a release build, because status
appears unused then. I'm not certain the ugly trick I used here will
convince all compilers to shut up about status (status is always "used" now,
as the first (ignored) clause in a comma expression).
impossible to remember, so renamed one to something obvious. Headed
off potential signed-vs-unsigned compiler complaints I introduced by
changing the type of a vrbl to unsigned. Removed the need for the
tedious explanation about "backward pointer loops" by looping on an
int instead.
result.
list_resize(): Document the intent. Code is increasingly relying on
subtle aspects of its behavior, and they deserve to be spelled out.
list_ass_slice(): A bit more simplification, by giving it a common
error exit and initializing more values.
Be clearer in comments about what "size" means (# of elements? # of
bytes?).
While the number of elements in a list slice must fit in an int, there's
no guarantee that the number of bytes occupied by the slice will. That
malloc() and memmove() take size_t arguments is a hint about that <wink>.
So changed to use size_t where appropriate.
ihigh - ilow should always be >= 0, but we never asserted that. We do
now.
The loop decref'ing the recycled slice had a subtle insecurity: C doesn't
guarantee that a pointer one slot *before* an array will compare "less
than" to a pointer within the array (it does guarantee that a pointer
one beyond the end of the array compares as expected). This was actually
an issue in KSR's C implementation, so isn't purely theoretical. Python
probably has other "go backwards" loops with a similar glitch.
list_clear() is OK (it marches an integer backwards, not a pointer).
though I tried to be very careful. This is a slight simplification, and it
adds a new feature: a small stack-allocated "recycled" array for the cases
when we don't remove too many items.
It allows PyList_SetSlice() to never fail if:
* you are sure that the object is a list; and
* you either do not remove more than 8 items, or clear the list.
This makes a number of other places in the source code correct again -- there
are some places that delete a single item without checking for MemoryErrors
raised by PyList_SetSlice(), or that clear the whole list, and sometimes the
context doesn't allow an error to be propagated.
invariants allows the ob_item != NULL check to be replaced with an
assertion.
* Added assertions to list_init() which document and verify that the
tp_new slot establishes the invariants. This may preclude a future
bug if a custom tp_new slot is written.
to NULL during the lifetime of the object.
* listobject.c nevertheless did not conform to the other invariants,
either; fixed.
* listobject.c now uses list_clear() as the obvious internal way to clear
a list, instead of abusing list_ass_slice() for that. It makes it easier
to enforce the invariant about ob_item == NULL.
* listsort() sets allocated to -1 during sort; any mutation will set it
to a value >= 0, so it is a safe way to detect mutation. A negative
value for allocated does not cause a problem elsewhere currently.
test_sort.py has a new test for this fix.
* listsort() leak: if items were added to the list during the sort, AND if
these items had a __del__ that puts still more stuff into the list,
then this more stuff (and the PyObject** array to hold them) were
overridden at the end of listsort() and never released.
mutation during list.sort() used to rely on that listobject.c always
NULL'ed ob_item when ob_size fell to 0. That's no longer true, so the
test for list mutation during a sort is no longer reliable. Changed the
test to rely instead on that listobject.c now never NULLs-out ob_item
after (if ever) ob_item gets a non-NULL value. This new assumption is
also documented now, as a required invariant in listobject.h.
The new assumption allowed some real simplification to some of the
hairier code in listsort(), so is a Good Thing on that count.
__oct__, and __hex__. Raise TypeError if an invalid type is
returned. Note that PyNumber_Int and PyNumber_Long can still
return ints or longs. Fixes SF bug #966618.
- weakref.ref and weakref.ReferenceType will become aliases for each
other
- weakref.ref will be a modern, new-style class with proper __new__
and __init__ methods
- weakref.WeakValueDictionary will have a lighter memory footprint,
using a new weakref.ref subclass to associate the key with the
value, allowing us to have only a single object of overhead for each
dictionary entry (currently, there are 3 objects of overhead per
entry: a weakref to the value, a weakref to the dictionary, and a
function object used as a weakref callback; the weakref to the
dictionary could be avoided without this change)
- a new macro, PyWeakref_CheckRefExact(), will be added
- PyWeakref_CheckRef() will check for subclasses of weakref.ref
This closes SF patch #983019.
The builtin eval() function now accepts any mapping for the locals argument.
Time sensitive steps guarded by PyDict_CheckExact() to keep from slowing
down the normal case. My timings so no measurable impact.
tests which nicely highly highlight weaknesses).
* Initial value is now a large prime.
* Pre-multiply by the set length to add one more basis of differentiation.
* Work a bit harder inside the loop to scatter bits from sources that
may have closely spaced hash values.
All of this is necessary to make up for keep the hash function commutative.
Fortunately, the hash value is cached so the call to frozenset_hash() will
only occur once per set.
* Non-zero initial value so that hash(frozenset()) != hash(0).
* Final permutation to differentiate nested sets.
* Add logic to make sure that -1 is not a possible hash value.
Michael W. Hudson
Brett Cannon
Tim Peters
Armin Rigo
Jeremy Hylton
Raymond Hettinger
Hye-Shik Chang
Fred Drake
Marc-André Lemburg
Neil Schemenauer
Nicholas Bastin
Neal Norwitz
Martin v. Löwis
Anthony Baxter
Skip Montanaro