[issue46512] Explicit or correct behavior of filecmp.cmpfiles w/ absolute path names
New submission from bers :
It is very easy to use filecmp.cmpfiles incorrectly by passing absolute path
names. This is because
1. the documentations does not say that relative path names have to be passed,
and
2. filecmp.cmpfiles does not issue a warning when absolute path names are
passed.
Consider this example code, which does look sensible at first glance:
files = dir_a.glob("*")
(equal, _, _) = filecmp.cmpfiles(dir_a, dir_b, files, shallow=False)
print("equal:", *equal)
However, in the full example below, you will see that this code fails to detect
that two files are actually different.
"""Demo behavior of filecmp.cmpfiles with absolute path names."""
import filecmp
import tempfile
from pathlib import Path
with tempfile.TemporaryDirectory() as tmpdirname:
# prepare two different files
tmpdir = Path(tmpdirname)
dir_a = tmpdir / "a"
dir_b = tmpdir / "b"
file_a = dir_a / "foo.txt"
file_b = dir_b / "foo.txt"
dir_a.mkdir()
dir_b.mkdir()
file_a.write_text("A")
file_b.write_text("B")
# actually diff the files
files = dir_a.glob("*")
# filecmp should issue a warning here!
(equal, _, _) = filecmp.cmpfiles(dir_a, dir_b, files, shallow=False)
# otherwise, this result is easy to misinterpret - files are reported as
equal
print("equal:", *equal)
--
components: Library (Lib)
messages: 411570
nosy: bers
priority: normal
severity: normal
status: open
title: Explicit or correct behavior of filecmp.cmpfiles w/ absolute path names
type: behavior
versions: Python 3.9
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[issue46512] filecmp.cmpfiles w/ absolute path names
bers added the comment:
> Did your example work with relative paths?
Yes, it does. Just append the following to my example code:
# actually diff the files - correctly!
files = [f.relative_to(dir_a) for f in dir_a.glob("*")]
(_, different, _) = filecmp.cmpfiles(dir_a, dir_b, files, shallow=False)
print("different:", *different)
Output then is
equal: C:\Users\bers\AppData\Local\Temp\tmp1p6jh4rg\a\foo.txt
different: foo.txt
--
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[issue36122] Second run of 2to3 continues to modify output
New submission from bers : I did this on Windows 10: P:\>python --version Python 3.7.2 P:\>echo print 1, 2 > Test.py P:\>python Test.py File "Test.py", line 1 print 1, 2 ^ SyntaxError: Missing parentheses in call to 'print'. Did you mean print(1, 2)? P:\>2to3 -w Test.py RefactoringTool: Skipping optional fixer: buffer RefactoringTool: Skipping optional fixer: idioms RefactoringTool: Skipping optional fixer: set_literal RefactoringTool: Skipping optional fixer: ws_comma RefactoringTool: Refactored Test.py --- Test.py (original) +++ Test.py (refactored) @@ -1 +1 @@ -print 1, 2 +print(1, 2) RefactoringTool: Files that were modified: RefactoringTool: Test.py P:\>python Test.py 1 2 P:\>2to3 -w Test.py RefactoringTool: Skipping optional fixer: buffer RefactoringTool: Skipping optional fixer: idioms RefactoringTool: Skipping optional fixer: set_literal RefactoringTool: Skipping optional fixer: ws_comma RefactoringTool: Refactored Test.py --- Test.py (original) +++ Test.py (refactored) @@ -1 +1 @@ -print(1, 2) +print((1, 2)) RefactoringTool: Files that were modified: RefactoringTool: Test.py P:\>python Test.py (1, 2) Note how "print 1, 2" first becomes "print(1, 2)" (expected), then becomes "print((1, 2))" in the following run. This changes the output of Test.py -- components: 2to3 (2.x to 3.x conversion tool) messages: 336653 nosy: bers priority: normal severity: normal status: open title: Second run of 2to3 continues to modify output type: enhancement versions: Python 3.7 ___ Python tracker <https://bugs.python.org/issue36122> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue36122] Second run of 2to3 continues to modify output
bers added the comment: Yes, understood! Thanks for the explanation. -- stage: -> resolved status: open -> closed ___ Python tracker <https://bugs.python.org/issue36122> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
