anatoly techtonik <techto...@gmail.com> added the comment: On Mon, Sep 20, 2010 at 11:58 PM, Terry J. Reedy <rep...@bugs.python.org> wrote: > Given that difflib produces unified diffs (among 3 others) and that diff.py > is a thin command-line wrapper that provides access to all 4 formats (with no > default), I consider those two files 'ready'.
Context diff is default format for diff.py utility. I tried my best to change this, but failed, and that's very disappointing in Python community. You may take a look how much time was wasted on a decision for a file that is neither part of standard library nor really used by anyone participated except me. http://bugs.python.org/issue8355 > So I presume you are referring to your patch.py, which is still labelled > experimental. > > Difflib works by analyzing sequences a and b with SequenceMatcher to produce > a sequence of edits that would produce b from a. It then formats the edits > into 1 of 4 formats. > > Ideally, a patchlib would have a core SequenceEditor that would apply a > sequence of edits (in the same format as SequenceMatcher's outputs) to > sequence a to output sequence b. That much seems relatively easy. To be > complete, it should also have at least 3 if not 4 parse functions that would > produce edit sequences. A corresponding patch.py would then be a thin > command-line wrapper over patchlib. Difflib doesn't produce correct output for unified format, and patch.py is not able to parse it correctly - see issue2142, issue7585 (for Python 2.6). patch.py doesn't operate with sequences of edits - it has line by line parser (rather than symbol by symbol), which produces list of filenames with info about changed lines in hunk objects (containing line numbers). There is no SequenceEditor sequences. > Your comments and a perusal of your code indicates that it has a unified diff > parser, a sequence matcher, and command-line wrapper. I guess the immediate > question is whether this would be enough for a start. Unified diff parser is valid only for Subversion style patches. Patches produced by difflib are not valid as stated above. Mercurial and git style patches are about to be added later with an ability to create and copy/move files. Sequence matcher is line comparison tool with some intelligence to free developer from CRLF difference sufferings. It is good for "apply patch" use case, but I do not know how about low-level SequenceEditor API. Usually patch utilities contains more additional logic to apply patches with some offset. http://code.google.com/p/google-diff-match-patch/ will be a better point for low level difflib API. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue2057> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
