Dennis Sweeney added the comment:
Being in different modules is irrelevant. Attribute names that start with
double underscores and don't end with double underscores are "mangled" by the
compiler to include the class name as well:
>>> class MyClass:
...
Dennis Sweeney added the comment:
The parser rejects this ambiguity and requires parentheses:
[
xxx
for item in collection
if (xxx := mutator(item)) is not None
]
Example ambiguity:
>>> [x for item in "abcdefabc" if x := item.upper() not in "ABC"
Dennis Sweeney added the comment:
How is proposed_function("abcd", max_repeat=3) any different from what you can
currently spell as combinations("aaabbbcccddd") ? Or, more generally,
def proposed_function(it, repeats)
repeated = chain.from_iterable([x] * repeat for
Dennis Sweeney added the comment:
Good catch -- with interning, the cutoff is more like 20-50, so it's probably
not worth optimizing for.
Before:
1 --> 1.67e-07
2 --> 1.77e-07
3 --> 1.90e-07
4 --> 2.05e-07
5 --> 2.14e-07
6 --> 2.35e-07
7 --> 2.51e-07
8 --> 2.
Change by Dennis Sweeney :
--
keywords: +patch
pull_requests: +24817
stage: -> patch review
pull_request: https://github.com/python/cpython/pull/26200
___
Python tracker
<https://bugs.python.org/issu
New submission from Dennis Sweeney :
This patch ensures keyword-passing happens in linear time, fulfilling the
26-year-old TODO comment in ceval.c:
XXX speed up searching for keywords by using a dictionary
from time import perf_counter
from itertools import repeat
def bench(N):
reps
Dennis Sweeney added the comment:
I'm getting the following FutureWarning on a certain regular expression. I
think it just needs "[]" to become "\[\]".
0:05:36 load avg: 0.00 [ 53/427] test_check_c_globals
...\Tools\c-analyzer\c_common\tables.py:236: FutureWarning:
Dennis Sweeney added the comment:
How are you trying to start the shell? Does "shell window" mean IDLE? What
operating system are you using? What do you mean by "it glitches"?
--
nosy: +Dennis Sweeney
___
Python tracker
<
Change by Dennis Sweeney :
--
pull_requests: +24662
pull_request: https://github.com/python/cpython/pull/26012
___
Python tracker
<https://bugs.python.org/issue40
Dennis Sweeney added the comment:
I tried some debugging code:
diff --git a/Python/ceval.c b/Python/ceval.c
index f745067069..a8668dbac2 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4864,6 +4864,18 @@ get_exception_handler(PyCodeObject *code, int index)
return res
Dennis Sweeney added the comment:
Your suspicion looks correct, random() is faster:
.\python.bat -m pyperf timeit -s "from random import choices"
"choices(range(100), k=10_000)"
Before int_choices.diff: Mean +- std dev: 1.49 ms +- 0.09 ms
After int_choices.diff: Mean
New submission from Dennis Sweeney :
Problem: Random.choices() never returns sequence entries at large
odd indices. For example:
>>> import random
>>> [x % 2 for x in random.choices(range(2**53), k=20)]
[0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1
Dennis Sweeney added the comment:
I think the docs are correct. For example:
>>> import subprocess
>>> subprocess.run("ls", check=True, stdout=subprocess.PIPE).stdout
>>> subprocess.check_output("ls")
--
nosy: +Dennis Sweeney
___
Dennis Sweeney added the comment:
I unfortunately don't have the time/internet access this week to do a PR.
--
___
Python tracker
<https://bugs.python.org/issue44
Dennis Sweeney added the comment:
Another idea: do what test_exceptions() does:
try:
f()
except NameError as exc:
with support.captured_stderr() as err:
sys.__excepthook__(*sys.exc_info())
self.assertNotIn("a1", er
Dennis Sweeney added the comment:
Indeed, this change enables the feature for IDLE, though I'm not sure what it
breaks.
diff --git a/Lib/idlelib/run.py b/Lib/idlelib/run.py
index 07e9a2bf9c..319b16f311 100644
--- a/Lib/idlelib/run.py
+++ b/Lib/idlelib/run.py
@@ -569,7 +569,7 @@ def runcode
Dennis Sweeney added the comment:
It looks like Lib/idlelib/run.py : print_exception() re-implements the
traceback, rather than relying on sys.excepthook
--
___
Python tracker
<https://bugs.python.org/issue44
Dennis Sweeney added the comment:
PyErr_Display() grabs the current sys.stderr and writes to that, but it looks
like IDLE never gets to call PyErr_Display().
--
___
Python tracker
<https://bugs.python.org/issue44
Dennis Sweeney added the comment:
I'm not sure if this helps, but this is the relevant tree of callers:
suggestions.c: _Py_Offer_Suggestions() (the expected behavior) is only
referenced by
pythonrun.c: print_exception(), which is only referenced by
pythonrun.c: print_exception_recursive
Change by Dennis Sweeney :
--
nosy: +pablogsal
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New submission from Dennis Sweeney :
After bpo-38530, I get this in the python shell:
Python 3.10.0b1 (tags/v3.10.0b1:ba42175, May 3 2021, 20:22:30) [MSC v.1928 64
bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more info
Dennis Sweeney added the comment:
PR 25776 is a work in progress for what it might look like to do a few things:
- Make case-swaps half the cost of any other edit
- Refactor Levenshtein code to not use memory allocator, and to bail early on
no match.
- Add comments to Levenshtein distance
Change by Dennis Sweeney :
--
pull_requests: +24466
pull_request: https://github.com/python/cpython/pull/25776
___
Python tracker
<https://bugs.python.org/issue38
Dennis Sweeney added the comment:
Some research of other projects:
LLVM [1][2]
---
- Compute Levenshtein
- Using O(n) memory rather than O(n^2)
- Uses UpperBound = (len(typo) + 2) // 3
GCC [3]
---
- Uses Damerau-Levenshtein distance
- Counts transpositions like "
Dennis Sweeney added the comment:
I opened PR 25584 to fix this current behavior:
>>> v
Traceback (most recent call last):
File "", line 1, in
NameError: name 'v' is not defined. Did you mean: 'id'?
>>> vv
Traceback (most recent call last):
File "&
Change by Dennis Sweeney :
--
nosy: +Dennis Sweeney
nosy_count: 8.0 -> 9.0
pull_requests: +24304
pull_request: https://github.com/python/cpython/pull/25584
___
Python tracker
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Dennis Sweeney added the comment:
Running kill_subprocess.py on Windows 10, I get these results:
Python 3.7.2 (tags/v3.7.2:9a3ffc0492)
- raises NotImplementedError in base_events.py, _make_subprocess_transport
Python 3.8.2 (tags/v3.8.2:7b3ab59)
- Success
Python 3.9.0 (tags/v3.9.0
Dennis Sweeney added the comment:
Okay, the PR should fix those problems now.
I am still apprehensive about whether all of the corner cases are covered, so
reviews are welcome, as are suggestions of more test cases.
--
___
Python tracker
<ht
Dennis Sweeney added the comment:
A bug was reported in anext(): https://bugs.python.org/issue43751
--
nosy: +Dennis Sweeney
___
Python tracker
<https://bugs.python.org/issue31
Dennis Sweeney added the comment:
That change fixes that bug, but I think there may be another bug involving when
a custom async iterator is passed rather than an async generator. This is at
the limit of my knowledge, so any guidance would be appreciated. The test I
wrote in the PR
Change by Dennis Sweeney :
--
keywords: +patch
pull_requests: +23976
stage: -> patch review
pull_request: https://github.com/python/cpython/pull/25238
___
Python tracker
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Dennis Sweeney added the comment:
I can open a PR this evening, but I think this is close to the issue:
PyIter_Next() already silences StopIteration, so checking for it afterward
fails.
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index f0c6b79917..95f4659dc9 100644
Dennis Sweeney added the comment:
Looks like we both opened PRs in the same minute.
The MAGIC constant didn't get updated, but perhaps that can just be included in
the Minor Corrections PR.
I'd bet a CI check could be added to check that if the opcodes change then
Python
Change by Dennis Sweeney :
--
nosy: +Dennis Sweeney
nosy_count: 1.0 -> 2.0
pull_requests: +23962
pull_request: https://github.com/python/cpython/pull/25225
___
Python tracker
<https://bugs.python.org/issu
Dennis Sweeney added the comment:
Correction: I opened GH-25172
--
___
Python tracker
<https://bugs.python.org/issue43719>
___
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Dennis Sweeney added the comment:
I could not successfully build even with deletion of __pycache__ in subfolders.
I finally got the build to succeed after changing the magic number, so I opened
GH-25069.
--
___
Python tracker
<ht
Change by Dennis Sweeney :
--
pull_requests: +23913
pull_request: https://github.com/python/cpython/pull/25172
___
Python tracker
<https://bugs.python.org/issue27
Dennis Sweeney added the comment:
I notice this in _bootstrap_external.py: the magic number did not get changed,
only the comment:
# Python 3.10a2 3433 (RERAISE restores f_lasti if oparg != 0)
# Python 3.10a6 3434 (PEP 634: Structural Pattern Matching)
# Python 3.10a7 3435 Use
Dennis Sweeney added the comment:
I ran into the same issue on Windows 10 and git bisected it to the same first
bad commit, fcb55c0037baab6f98f91ee38ce84b6f874f034a
The issue persists after rm .\Parser\__pycache__\*
My .\Tools directory has no __pycache__.
--
nosy: +Dennis Sweeney
Dennis Sweeney added the comment:
It's well-known that regular expressions can take exponential time. You can try
searching this bug tracker for "re exponential". Common suggestions are to try
a third-party module, or to write better regexes where possible. Note that the
impo
Dennis Sweeney added the comment:
typing.cast doesn't actually do anything, it only exists as a hint for
type-checkers.
As William noted, using the 3-argument type(...) as you showed will only return
a type, not a mcs.
I think you may want super().__new__(mcs, name, bases, namespace
Dennis Sweeney added the comment:
> other attributes will not be copied
The signature of wraps() is
wraps(wrapped, assigned=('__module__', '__name__', '__qualname__',
'__doc__', '__annotations__'), updated=('__dict__',))
Passing the updated=() will prevent the __dict__ from be
Dennis Sweeney added the comment:
Did you try adding updated=()?
@functools.wraps(_internal_main_operation, updated=())
def external_main_operation(self, *args, **kwargs):
--
___
Python tracker
<https://bugs.python.org/issue43
Dennis Sweeney added the comment:
Can you explain why you think this is the wrong behavior, and what operating
system and version of Python you're using?
from https://docs.python.org/3/library/time.html#time.perf_counter
Return the value (in fractional seconds) of a performance counter
Dennis Sweeney added the comment:
> the ABC wouldn't have any abstract methods,
I was wrong about this since the @abstractmethod decorator adds 'f' to the
__abstractmethods__ set of the ABC, but the rest of my comment stands.
--
___
Pyt
Dennis Sweeney added the comment:
I don't think changing @wraps is what you want. Even if you manually set
`wrapper.__isabstractmethod__ = False`, you won't reach `print('f is
called!')`, since f() is overridden by the child. And if you do that, the ABC
wouldn't have any abstract methods
Change by Dennis Sweeney :
--
pull_requests: +23564
pull_request: https://github.com/python/cpython/pull/24796
___
Python tracker
<https://bugs.python.org/issue41
Dennis Sweeney added the comment:
If the argument clinic is too disruptive, would it be okay to inline the
equivalent code like this?
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 90bafb0ea8..d75388abc8 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules
Change by Dennis Sweeney :
--
pull_requests: +23457
pull_request: https://github.com/python/cpython/pull/24672
___
Python tracker
<https://bugs.python.org/issue41
Dennis Sweeney added the comment:
Any chance PR 22904 can make it into 3.10 before the May 03 feature freeze? The
text document in that PR has some notes on how the algorithm works, so that may
be a good place to start reviewing if anyone is interested
Dennis Sweeney added the comment:
If I understand correctly, changing the -1 to a -2 does not actually make the
program "crash" -- you just only see one black circle.
The reason is that range(40, 0, -2) produces 40, 38, 36, etc., all of which are
even numbers, so rad % 2 is always
Dennis Sweeney added the comment:
This seems like a very specific use case. Too specific IMO for a method on all
string objects for anyone using Python anywhere in the world. Why not just
write a function like this?
def my_join(strings, sep=", ", last_sep=", and &quo
Dennis Sweeney added the comment:
I bisected the change to here:
https://github.com/python/cpython/pull/19881
commit 3dd2157febae5087cad24f69b6de9cbd13cd
Author: Raymond Hettinger
Date: Sun May 3 04:51:05 2020 -0700
Simplify set entry insertion logic. (GH-19881)
""&qu
Dennis Sweeney added the comment:
I think the strangeness is happening because sometimes, the warning is printed
to stderr, while other times, IDLE's parser notices the "is "
anti-pattern and raises a SyntaxError.
See the attached screenshot for the IDLE output versus the cons
Dennis Sweeney added the comment:
There may be reason to re-open this.
With Python 3.9.0, I see the inconsistent behavior that Gary describes only
when using IDLE. So this is likely an IDLE issue.
I attached a screenshot of the difference.
--
Added file: https://bugs.python.org
Dennis Sweeney added the comment:
This was a very intentional change from the commit
3bcbedc9f1471d957a30a90f9d1251516b422416
It's not safe to check `x is y` when x and y are strings.
You should always use `x == y` for strings instead.
In CPython, if the names x and y both refer to the same
Dennis Sweeney added the comment:
You could express this as:
a = [input() for i in range(10)]
x = input()
print(x in a)
This is more clear IMO, because if you want to have something happen before
something else, it's clearest to put them on separate lines, one after the
other.
I also
Dennis Sweeney added the comment:
This is the expected behavior.
>From
>https://docs.python.org/3/tutorial/introduction.html#first-steps-towards-programming
"""
In Python, like in C, any non-zero integer value is true; zero is false. The
condition may also be a
Dennis Sweeney added the comment:
I think this is the expected behavior.
It is expected by IEEE 754 that nan != nan, so that behavior exists:
>>> nan = float('nan')
>>> nan2 = float('nan')
>>> assert nan != nan2
>>> assert nan != nan
However, for "p
Dennis Sweeney added the comment:
I reproduced something similar in 3.9 with standard library modules:
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> zone = ZoneInfo(key='Etc/GMT-3')
>>> zone.tzname(datetime(2021, 1, 28))
'+0
Dennis Sweeney added the comment:
https://bugs.python.org/issue41545 is a duplicate of this.
In that report, there's an example of something that can go wrong with the
save-a-boolean-per-context-manager approach even when threads are not used, but
when concurrent generators are used, like
Dennis Sweeney added the comment:
It looks like this was a duplicate of https://bugs.python.org/issue31356
--
___
Python tracker
<https://bugs.python.org/issue41
Dennis Sweeney added the comment:
PR 22904 now adds a text document explaining how the Two-Way algorithm works in
much more detail.
I was looking at more benchmarking results, and I came to a couple of
conclusions about cutoffs.
There's a consistent benefit to using the two-way algorithm
Change by Dennis Sweeney :
--
keywords: +patch
pull_requests: +22892
stage: -> patch review
pull_request: https://github.com/python/cpython/pull/24058
___
Python tracker
<https://bugs.python.org/issu
New submission from Dennis Sweeney :
# common case
.\python.bat -m pyperf timeit "type(17)"
Master: 49.9 ns +- 1.8 ns ---> PR: 33.3 ns +- 1.4 ns
# uncommon case
.\python.bat -m pyperf timeit "type('A', (object, ), {})"
Master: 5.14 us +- 0.04 us ---&
Dennis Sweeney added the comment:
Were you able to run PCbuild\get_externals.bat ?
--
___
Python tracker
<https://bugs.python.org/issue42804>
___
___
Python-bug
Dennis Sweeney added the comment:
What commands did you enter? Are you following the instructions at
https://devguide.python.org/setup/ ?
--
nosy: +Dennis Sweeney
___
Python tracker
<https://bugs.python.org/issue42
Dennis Sweeney added the comment:
This is not a bug. See https://stackoverflow.com/a/10825998/11461120
--
nosy: +Dennis Sweeney
___
Python tracker
<https://bugs.python.org/issue42
Dennis Sweeney added the comment:
To make it slightly more readable and future-proof so such things don't become
outdated again in the future, you could use the CodeType.replace() method.
See also https://bugs.python.org/issue42422
--
nosy: +Dennis Sweeney
Dennis Sweeney added the comment:
This is just how local/nonlocal/global/builtin variables work in Python.
When you assign to a name anywhere inside of a function, all occurrences of
that name refer by default to a local variable. So the line "ZeroDivisionError
= 1" tells the foo(
Change by Dennis Sweeney :
Added file: https://bugs.python.org/file49674/twoway_demo.py
___
Python tracker
<https://bugs.python.org/issue41972>
___
___
Python-bugs-list m
Change by Dennis Sweeney :
Removed file: https://bugs.python.org/file49672/twoway_demo.py
___
Python tracker
<https://bugs.python.org/issue41972>
___
___
Python-bug
Dennis Sweeney added the comment:
For convenience, attached is a quick and dirty Tkinter GUI that lets you step
through the Crochemore/Perrin Algorithm on your choice of inputs, just for
play/discovery.
A good illustration of the memory for periodic needles can be found by testing
Dennis Sweeney added the comment:
Why not just fix bogus_code_obj.py?
Something like this (using the replace method) would make it more future-proof
to similar changes in the code object constructor signature (and be more
readable!):
import dis
POP_TOP = dis.opmap['POP_TOP']
wordcode
Dennis Sweeney added the comment:
I'll add that for 98% of the use cases of a linked list (where you just want
fast access at the ends), you can use a `collections.deque` instead, and it
will be faster (fewer dereferences) and more memory-efficient (fewer pointers
to store
Dennis Sweeney added the comment:
Maybe you're looking for re.fullmatch:
https://docs.python.org/3/library/re.html#re.fullmatch
--
nosy: +Dennis Sweeney
___
Python tracker
<https://bugs.python.org/issue42
Dennis Sweeney added the comment:
sys.getrecursionlimit() returns whatever was passed to the most recent call of
sys.setrecursionlimit(...), with some system default (here 1000).
Catching a RecursionError might be fine sometimes, but the issue is that
Program 1 catches a RecursionError
Dennis Sweeney added the comment:
This might be the expected behavior. See https://bugs.python.org/issue25222
If you already caught a RecursionError and you keep recursing anyway, once you
go 50 levels beyond sys.getrecursionlimit(), the interpreter crashes regardless
of what is `except`ed
Dennis Sweeney added the comment:
>From
>https://github.com/python/cpython/blob/master/Lib/test/crashers/bogus_code_obj.py
> :
"""
Broken bytecode objects can easily crash the interpreter.
This is not going to be fixed. It is generally agreed that there is no
poi
Dennis Clarke added the comment:
I see :
https://github.com/python/cpython/blob/master/Objects/exceptions.c#L2316
the void return has been fixed and really I should not be
looked anywhere else other than the master sources on some
oddball platform. I will start over
Dennis Clarke added the comment:
I gave up on trying to compile this code with C99. Trying C11 and
hope that blows up in different places.
--
___
Python tracker
<https://bugs.python.org/issue42
New submission from Dennis Clarke :
Seems related to issue42173 where the idea on the table was, simply to
drop Solaris support and to quote Mr Stinner to "let the code slowly
die". Regardless of this sort of neglect there are people who do try
to use Python on big endian ri
Dennis Sweeney added the comment:
Here's an example:
class A(complex):
def __init__(self, *args, test):
self.test = test
def __new__(cls, *args, test):
return super().__new__(cls, *args)
>>> a = A(1, test="TEST")
>>> a
(1+0j)
>>>
Dennis Sweeney added the comment:
This is because int, str, and complex are immutable. If I have
class MyInt(int):
def __init__(self, stuff):
pass
then when I call MyInt("19"), the string "19" is passed to the constructor
int.__new__ b
Dennis Sweeney added the comment:
> Toward that end it would be fine to use "very high" cutoffs, and save tuning
> for later.
This feels reasonable to me -- I changed the cutoff to the more cautious `if (m
>= 100 && n - m >= 5000)`, where the averages are v
Dennis Sweeney added the comment:
I used the following script, and the raw results are attached.
import pyperf
runner = pyperf.Runner()
ms = [12, 16, 24, 32, 48, 64, 96, 128,
192, 256, 384, 512, 768, 1024, 1536]
ns = [2000, 3000, 4000, 6000, 8000,
12000
Dennis Sweeney added the comment:
I am attempting to better understand the performance characteristics to
determine where a cutoff should go.
Attached is a colorful table of benchmarks of the existing algorithm to the PR
with the cutoff changed to `if (1)` (always two-way) or `if (0
Dennis Sweeney added the comment:
Here are those zipf-distributed benchmarks for PR 22904:
https://pastebin.com/raw/qBaMi2dm
Ignoring differences of <5%, there are 33 cases that get slower, but 477 cases
that got faster.
Here's a stringbench.py run for PR 22904: https://pastebin.com/
Dennis Sweeney added the comment:
This is the approach in the PR:
# JUMP_BOTH
while ...:
if haystack[j + cut] != needle[cut]:
# Sunday skip
j += table[haystack[j + len(needle)]]
continue
j += rest_of_the_two_way_algorithm()
If I
Dennis Sweeney added the comment:
I attached a new PR, with a lot of the same ideas.
The major differences between this and the last PR:
* The first character to be checked at each alignment is the first character of
the right half, rather than the last.
* If that first character does
Change by Dennis Sweeney :
--
pull_requests: +21836
pull_request: https://github.com/python/cpython/pull/22904
___
Python tracker
<https://bugs.python.org/issue41
Dennis Sweeney added the comment:
Unfortunately due to licensing issues, it looks like I'll have to ditch the PR
and start from scratch: it was too heavily based on the glibc implementation,
which has a stricter license. It may be take a good deal of time before I have
a potential
Dennis Sweeney added the comment:
I posted the example thinking that having a concrete walkthrough might be good
for discussion, and it looks like it was. ;-)
This makes me curious how a simplified-but-not-as-simplified-as-the-status-quo
Sunday algorithm would fare: using the Sunday
Dennis Sweeney added the comment:
> Dennis, I think that's expected, right? Two-way on its own can exploit
> nothing about individual characters - it only preprocesses the needle to
> break the possibility for quadratic-time behavior due to periods in the
> needle.
Yes, th
Dennis Sweeney added the comment:
FWIW, one of the "# Made the spaces line up" is actually a "skip ahead by the
needle length".
--
___
Python tracker
<https://bug
Dennis Sweeney added the comment:
Below is one of the tests that got run when I happened to import something, and
I thought it was a good illustration of the Boyer-Moore bad character shift
table.
It's worth noting in particular that the table is the dominant force for speed
in some common
Dennis Sweeney added the comment:
> But there _also_ seem to be real (but much smaller) benefits
> for the "search backward" cases, which I don't recall seeing
> when I tried it. Do you have a guess as to why?
I did change `skip = mlast - 1;` to `skip = mlast;` as you
Dennis Sweeney added the comment:
I added the cutoff for strings >= 10 characters, and I converted the PR from a
draft to "Ready to Review."
When running stringbench.py before and after the PR, I get these results:
Summary:
Unicode Before: 81.82 Bytes Before: 92.62
Dennis Sweeney added the comment:
I'm doing a couple more timing tests to try to understand exactly when the
cutoff should be applied (based on some combination of needle and haystack
lengths).
Can the rolling hash algorithm be made to go sublinear like O(n/m)? It looked
like it was pretty
Dennis Sweeney added the comment:
The most recent batch of commits added a jump table.
Between master and PR 22679 now, there are 151 cases slower than master and 463
that faster than master.
The slower cases are at most twice as slow, but the faster cases are often
10-20x faster.
I could
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