On Thu, Jun 07, 2012 at 12:03:30PM +0800, Zhou Zheng Sheng wrote:
> Hi,
>
> Since there is no coverage report on tests in vdsm, if a PEP 8 patch
> passes the tests, we still not sure if there is no mistake in it.
> Viewing the diff reports on all the changes consumes a lot of time, and
> some small but fatal mistakes(like misspelling variable name) can easily
> be ignored by human eyes.
>
> So I have a try on the compiler module of Python. I write a tool named
> 'pydiff'. pydiff parses two Python scripts into Abstract Syntax Trees.
> These data structures can reflect the logic of the code, and pydiff
> performs a recursive compare on the trees. Then pydiff reports
> differences and the corresponding line numbers. In this way, pydiff
> ignores code style changes, and reports only logical changes of the code.
>
> I think this tool can save us a lot of time. After a PEP 8 patch passes
> vdsm tests and pydiff, I will get some confidence on the patch and it
> probably does not break anything in vdsm.
This is a very nice tool. Thanks for sharing it. I would like to see all
authors of PEP8 patches use this to check their patches for semantic
correctness. This should greatly improve our ability to complete the PEP8
cleanup quickly.
> Here is a usage example:
>
> -------- test_o.py --------
> def foo(a, b):
> pass
>
> if __name__ == '__main__':
> A = [1, 2, 3]
> print (4, 5, 6), \
> "over"
> foo(1, 2)
> print 'Hello World'
>
>
> -------- test_n.py --------
> def foo(a, b):
> pass
>
> if __name__ == '__main__':
> A = [1,
> 2, 3]
> print (4, 5, 6), "over"
> fooo(
> 1, 2)
> print ('Hello '
> 'World')
>
>
> Some differences of the files are just a matter of style. The only
> significant difference is the function call "foo()" is misspelled in
> "test_n.py".
>
> Run pydiff.py, it will report:
>
> $ python pydiff.py test_*.py
> 1 difference(s)
> first file: test_n.py
> second file: test_o.py
>
> ((8, 'fooo'), (8, 'foo'))
>
> This report tells us that 'fooo' in line 8 of "test_n.py" is different
> from 'foo' in line 8 of "test_o.py".
>
>
> It can also find insertions or deletions. Here is another simple example:
>
> ---- old.py ----
> print 'Hello 1'
> print 'Hello 2'
> print 'Hello 3'
> print 'Hello 4'
> print 'Hello 5'
>
> ---- new.py ----
> print 'Hello 1'
> print 'Hello 3'
> print 'Hello 4'
> print 'Hello 5'
> print 'Hello 5'
>
> Run pydiff:
>
> $ pydiff old.py new.py
> 2 difference(s)
> first file: old.py
> second file: new.py
>
> ((2, Printnl([Const('Hello 2')], None)), (2, None))
>
> ((5, None), (5, Printnl([Const('Hello 5')], None)))
>
> Here "((2, Printnl([Const('Hello 2')], None)), (2, None))" means there
> is a print statement in line 2 of old.py, but no corresponding statement
> in new.py, so we can know the statement is deleted in new.py.
> "((5, None), (5, Printnl([Const('Hello 5')], None)))" means there is a
> print statement in line 5 of new.py, but no corresponding statement in
> old.py, so we can know the statement is inserted in new.py.
>
>
> Sometimes the change in code logic is acceptable, for example, change
> "aDict.has_key(Key)" into "Key in aDict". pydiff can report a difference
> in this case, but it is up to the user to judge whether it's acceptable.
> pydiff is just a tool to help you finding these changes.
>
> I hope it can be helpful for PEP 8 patch reviewers. If you find any
> bugs, please let me know. The script is in the attachment.
>
> --
> Thanks and best regards!
>
> Zhou Zheng Sheng / 周征晟
> E-mail: zhshz...@linux.vnet.ibm.com
> Telephone: 86-10-82454397
>
> _______________________________________________
> vdsm-devel mailing list
> vdsm-devel@lists.fedorahosted.org
> https://fedorahosted.org/mailman/listinfo/vdsm-devel
--
Adam Litke <a...@us.ibm.com>
IBM Linux Technology Center
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