Some applications (e.g. traditional Unix diff, version control
systems) neither know nor care about the encodings of the files they
are comparing. They are textual, but to the diff utility they are just
bytes. This worked fine under Python 2, because all of the hardcoded
strings in difflib.py are ASCII, so could safely be combined with
old-style u'' strings. But it stopped working in 3.x.
The solution is to use surrogate escapes for a lossless
bytes->str->bytes roundtrip. That means {unified,context}_diff() can
continue to just handle strings without worrying about bytes. Callers
who have to deal with bytes will need to change to using diff_bytes().
Use case: Mercurial's test runner uses difflib to compare current hg
output with known good output. But Mercurial's output is just bytes,
since it can contain:
* file contents (arbitrary unknown encoding)
* filenames (arbitrary unknown encoding)
* usernames and commit messages (usually UTF-8, but not guaranteed
because old versions of Mercurial did not enforce it)
* user messages (locale encoding)
Since the output of any given hg command can include text in multiple
encodings, it is hopeless to try to treat it as decodable Unicode
text. It's just bytes, all the way down.
This is an elaboration of a patch by Terry Reedy.
svn+ssh://pythondev@svn.python.org/python/trunk
........
r80004 | r.david.murray | 2010-04-12 12:35:19 -0400 (Mon, 12 Apr 2010) | 13 lines
Issue #7585: use tab between components in unified and context diff headers.
Instead of spaces between the filename and date (or whatever the string
is that follows the filename, if any) use tabs. This is what the unix
'diff' command does, for example, and difflib was intended to follow
the 'standard' way of doing diffs. This improves compatibility with
patch tools. The docs and examples are also changed to recommended that
the date format used be the ISO 8601 format, which is what modern diff
tools emit by default.
Patch by Anatoly Techtonik.
........
Instead of spaces between the filename and date (or whatever the string
is that follows the filename, if any) use tabs. This is what the unix
'diff' command does, for example, and difflib was intended to follow
the 'standard' way of doing diffs. This improves compatibility with
patch tools. The docs and examples are also changed to recommended that
the date format used be the ISO 8601 format, which is what modern diff
tools emit by default.
Patch by Anatoly Techtonik.
number of tests, all because of the codecs/_multibytecodecs issue described
here (it's not a Py3K issue, just something Py3K discovers):
http://mail.python.org/pipermail/python-dev/2006-April/064051.html
Hye-Shik Chang promised to look for a fix, so no need to fix it here. The
tests that are expected to break are:
test_codecencodings_cn
test_codecencodings_hk
test_codecencodings_jp
test_codecencodings_kr
test_codecencodings_tw
test_codecs
test_multibytecodec
This merge fixes an actual test failure (test_weakref) in this branch,
though, so I believe merging is the right thing to do anyway.
imports e.g. test_support must do so using an absolute package name
such as "import test.test_support" or "from test import test_support".
This also updates the README in Lib/test, and gets rid of the
duplicate data dirctory in Lib/test/data (replaced by
Lib/email/test/data).
Now Tim and Jack can have at it. :)
horridly inefficient hack in regrtest's Compare class, but it's about as
clean as can be: regrtest has to set up the Compare instance before
importing a test module, and by the time the module *is* imported it's too
late to change that decision. The good news is that the more tests we
convert to unittest and doctest, the less the inefficiency here matters.
Even now there are few tests with large expected-output files (the new
cost here is a Python-level call per .write() when there's an expected-
output file).
Guido told me to do this <wink>.
Greatly expanded docstrings, and fleshed out with examples.
New std test.
Added new get_close_matches() function for ESR.
Needs docs, but LaTeXification of the module docstring is all it needs.
\CVS: ----------------------------------------------------------------------
Greg Ward
Berker Peksag
Raymond Hettinger
Terry Reedy
R. David Murray
Senthil Kumaran
Philip Jenvey
Benjamin Peterson
Georg Brandl
Thomas Wouters
Neal Norwitz
Gustavo Niemeyer
Tim Peters
Martin v. Löwis
Brett Cannon
Barry Warsaw