New submission from Weronika Patena <[email protected]>:
According to difflib.ndiff help, the optional linejunk argument is "A function
that should accept a single string argument, and return true iff the string is
junk." Presumably the point is to ignore the junk lines in the comparison.
But the function doesn't appear to actually do this - in fact I haven't been
able to make the linejunk argument change the output in any way.
Expected difflib.ndiff behavior with no linejunk argument given:
>>> test_lines_1 = ['# something\n', 'real data\n']
>>> test_lines_2 = ['# something else\n', 'real data\n']
>>> print ''.join(difflib.ndiff(test_lines_1,test_lines_2))
- # something
+ # something else
? +++++
real data
Now I'm providing a linejunk function to ignore all lines starting with '#',
but the output is still the same:
>>> print ''.join(difflib.ndiff(test_lines_1, test_lines_2,
linejunk=lambda line: line.startswith('#')))
- # something
+ # something else
? +++++
real data
In fact if I make linejunk always return True (or False), nothing changes
either:
>>> print ''.join(difflib.ndiff(test_lines_1, test_lines_2,
linejunk=lambda line: True))
- # something
+ # something else
? +++++
real data
It certainly looks like an error, although it's possible that I'm just
misunderstanding how this should work.
I'm using Python 2.6.5, on Ubuntu Linux 10.04.
----------
components: Library (Lib)
messages: 155992
nosy: patena, tim_one
priority: normal
severity: normal
status: open
title: difflib.ndiff appears to ignore linejunk argument
type: behavior
versions: Python 2.6
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Python tracker <[email protected]>
<http://bugs.python.org/issue14332>
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