untrackable objects are not tracked by the garbage collector. This can
reduce the size of collections and therefore the garbage collection overhead
on long-running programs, depending on their particular use of datatypes.
(trivia: this makes the "binary_trees" benchmark from the Computer Language
Shootout 40% faster)
The basic algorithm remains the same; the most significant speedups
come from the following three changes:
(1) normalize by shifting instead of multiplying and dividing
(2) the old algorithm usually did an unnecessary extra iteration of
the outer loop; remove this. As a special case, this means that
long divisions with a single-digit result run twice as fast as
before.
(3) make inner loop much tighter.
Various benchmarks show speedups of between 50% and 150% for long
integer divisions and modulo operations.
sizeof(Py_UNICODE) == 2, PyUnicode_FromWideChar now converts
each character outside the BMP to the appropriate surrogate pair.
Thanks Victor Stinner for the patch.
(backport of r70452 from py3k to trunk)
For simple uses for str.format(), this makes the typing easier. Hopfully this
will help in the adoption of str.format().
For example:
'The {} is {}'.format('sky', 'blue')
You can mix and matcth auto-numbering and named replacement fields:
'The {} is {color}'.format('sky', color='blue')
But you can't mix and match auto-numbering and specified numbering:
'The {0} is {}'.format('sky', 'blue')
ValueError: cannot switch from manual field specification to automatic field numbering
Will port to 3.1.
and cleanups in Objects/longobject.c. The most significant change is that
longs now use less memory: average savings are 2 bytes per long on 32-bit
systems and 6 bytes per long on 64-bit systems. (This memory saving already
exists in py3k.)
platforms. The previous code was fragile, depending on the twin
accidents that:
(1) in C, casting the double value 2.**63 to long returns the integer
value -2**63, and
(2) in Python, hash(-2**63) == hash(2**63).
There's already a test for this in test_hash.
- fix some places where counters into ob_digit were declared as
int instead of Py_ssize_t
- add (twodigit) casts where necessary
- fix code in _PyLong_AsByteArray that uses << on negative values
#4759: allow None as first argument of bytearray.translate(), for consistency with bytes.translate().
Also fix segfault for bytearray.translate(x, None) -- will backport this part to 3.0 and 2.6.
Mark Dickinson
Antoine Pitrou
Hirokazu Yamamoto
Benjamin Peterson
Georg Brandl
Eric Smith
Kristján Valur Jónsson
Raymond Hettinger
Amaury Forgeot d'Arc
Martin v. Löwis
Nick Coghlan