results list.
Originally it allocated 0 items and used the list growth during append. Now
it preallocates 12 items so the first few appends don't need list reallocs.
("Here are some words ."*2).split(None, 1) is 7% faster
("Here are some words ."*2).split() is is 15% faster
(Your milage may vary, see dealership for details.)
File parsing like this
for line in f:
count += len(line.split())
is also about 15% faster. There is a slowdown of about 3% for large
strings because of the additional overhead of checking if the append is
to a preallocated region of the list or not. This will be the rare case.
It could be improved with special case code but we decided it was not
useful enough.
There is a cost of 12*sizeof(PyObject *) bytes per list. For the normal
case of file parsing this is not a problem because of the lists have
a short lifetime. We have not come up with cases where this is a problem
in real life.
I chose 12 because human text averages about 11 words per line in books,
one of my data sets averages 6.2 words with a final peak at 11 words per
line, and I work with a tab delimited data set with 8 tabs per line (or
9 words per line). 12 encompasses all of these.
Also changed the last rstrip code to append then reverse, rather than
doing insert(0). The strip() and rstrip() times are now comparable.
this is on par with a corresponding find, and nearly twice as fast
as split(sep, 1)
full tests, a unicode version, and documentation will follow to-
morrow.
made a copy of the string using PyString_FromStringAndSize(s, n) and modify
the copied string in-place. However, 1 (and 0) character strings are shared
from a cache. This cause "A".replace("A", "a") to change the cached version
of "A" -- used by everyone.
Now may the copy with NULL as the string and do the memcpy manually. I've
added regression tests to check if this happens in the future. Perhaps
there should be a PyString_Copy for this case?
about "%u", "%lu" and "%zu" formats.
Since PyString_FromFormat and PyErr_Format have exactly the same rules
(both inherited from PyString_FromFormatV), it would be good if someone
with more LaTeX Fu changed one of them to just point to the other.
Their docs were way out of synch before this patch, and I just did a
mass copy+paste to repair that.
Not a backport candidate (this is a new feature).
zfill stringmethods, so they can create strings larger than 2Gb on 64bit
systems (even win64.) The unicode versions of these methods already did this
right.
This will hopefully get rid of some Coverity warnings, be a hint to
developers, and be marginally faster.
Some asserts were added when the type is currently known, but depends
on values from another function.
In C++, it's an error to pass a string literal to a char* function
without a const_cast(). Rather than require every C++ extension
module to put a cast around string literals, fix the API to state the
const-ness.
I focused on parts of the API where people usually pass literals:
PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type
slots, etc. Predictably, there were a large set of functions that
needed to be fixed as a result of these changes. The most pervasive
change was to make the keyword args list passed to
PyArg_ParseTupleAndKewords() to be a const char *kwlist[].
One cast was required as a result of the changes: A type object
mallocs the memory for its tp_doc slot and later frees it.
PyTypeObject says that tp_doc is const char *; but if the type was
created by type_new(), we know it is safe to cast to char *.
[ 1327110 ] wrong TypeError traceback in generator expressions
by removing the code that can stomp on the users' TypeError raised by the
iterable argument to ''.join() -- PySequence_Fast (now?) gives a perfectly
reasonable message itself. Also, a couple of tests.
Andrew Dalke
Fredrik Lundh
Bob Ippolito
Jack Diederich
Andrew M. Kuchling
Tim Peters
Martin v. Löwis
Thomas Wouters
Skip Montanaro
Neal Norwitz
Anthony Baxter
Georg Brandl
Guido van Rossum
Hye-Shik Chang
Jeremy Hylton
Michael W. Hudson
Neil Schemenauer