Insert an overflow check when the sequence repetition count is outside
the range of ints. The old code would pass random truncated bits to
sq_repeat() on a 64-bit machine.
Add an improvement wrinkle to Neil Schemenauer's change to int_mul
(rev. 2.79.6.3). The other type is only disqualified from sq_repeat when
it has the CHECKTYPES flag. This means that for extension types that
only support "old-style" numeric ops, such as Zope 2's ExtensionClass,
sq_repeat still trumps nb_multiply.
example of where this changes behavior is when a new-style instance
defines '__mul__' and '__rmul__' and is multiplied by an int. Before
the change the '__rmul__' method is never called, even if the int is the
left operand.
Make sure that tp_free frees the int the same way as tp_dealloc would.
This fixes the problem that Barry reported on python-dev:
>>> 23000 .__class__ = bool
crashes in the deallocator. This was because int inherited tp_free
from object, which uses the default allocator.
2.2. Bugfix candidate.
(trivial change in backport: "freefunc" -> "destructor")
Original patch(es):
python/dist/src/Objects/intobject.c:2.82
int_mul(): new and vastly simpler overflow checking. Whether it's
faster or slower will likely vary across platforms, favoring boxes
with fast floating point. OTOH, we no longer have to worry about
people shipping broken LONG_BIT definitions <0.9 wink>.
Bugfix candidate.
int_repr(): we've never had a buffer big enough to hold the largest
possible result on a 64-bit box. Now that we're using snprintf instead
of sprintf, this can lead to nonsense results instead of random stack
corruption.
Both int and long multiplication are changed to be more careful in
their assumptions about when one of the arguments is a sequence: the
assumption that at least one of the arguments must be an int (or long,
respectively) is still held, but the assumption that these don't smell
like sequences is no longer true: a subtype of int or long may well
have a sequence-repeat thingie!
PEP 238. Changes:
- add a new flag variable Py_DivisionWarningFlag, declared in
pydebug.h, defined in object.c, set in main.c, and used in
{int,long,float,complex}object.c. When this flag is set, the
classic division operator issues a DeprecationWarning message.
- add a new API PyRun_SimpleStringFlags() to match
PyRun_SimpleString(). The main() function calls this so that
commands run with -c can also benefit from -Dnew.
- While I was at it, I changed the usage message in main() somewhat:
alphabetized the options, split it in *four* parts to fit in under
512 bytes (not that I still believe this is necessary -- doc strings
elsewhere are much longer), and perhaps most visibly, don't display
the full list of options on each command line error. Instead, the
full list is only displayed when -h is used, and otherwise a brief
reminder of -h is displayed. When -h is used, write to stdout so
that you can do `python -h | more'.
Notes:
- I don't want to use the -W option to control whether the classic
division warning is issued or not, because the machinery to decide
whether to display the warning or not is very expensive (it involves
calling into the warnings.py module). You can use -Werror to turn
the warnings into exceptions though.
- The -Dnew option doesn't select future division for all of the
program -- only for the __main__ module. I don't know if I'll ever
change this -- it would require changes to the .pyc file magic
number to do it right, and a more global notion of compiler flags.
- You can usefully combine -Dwarn and -Dnew: this gives the __main__
module new division, and warns about classic division everywhere
else.
- Do not compile unicodeobject, unicodectype, and unicodedata if Unicode is disabled
- check for Py_USING_UNICODE in all places that use Unicode functions
- disables unicode literals, and the builtin functions
- add the types.StringTypes list
- remove Unicode literals from most tests.
This introduces:
- A new operator // that means floor division (the kind of division
where 1/2 is 0).
- The "future division" statement ("from __future__ import division)
which changes the meaning of the / operator to implement "true
division" (where 1/2 is 0.5).
- New overloadable operators __truediv__ and __floordiv__.
- New slots in the PyNumberMethods struct for true and floor division,
new abstract APIs for them, new opcodes, and so on.
I emphasize that without the future division statement, the semantics
of / will remain unchanged until Python 3.0.
Not yet implemented are warnings (default off) when / is used with int
or long arguments.
This has been on display since 7/31 as SF patch #443474.
Flames to /dev/null.
