[Python-bugs-list] [Bug #124051] ndiff bug: "?" lines are out-of-sync

[noreply@sourceforge.net]

Bug #124051, was updated on 2000-Dec-01 07:17
Here is a current snapshot of the bug.

Project: Python
Category: demos and tools
Status: Open
Resolution: None
Bug Group: None
Priority: 5
Submitted by: flight
Assigned to : tim_one
Summary: ndiff bug: "?" lines are out-of-sync

Details: I wonder if this result (the "?" line) of ndiff is intentional:

clapton:1> cat a
Millionen für so 'n Kamelrennen sind
clapton:2> cat b
Millionen für so "n Kamelrennen sind
clapton:3> /tmp/ndiff.py -q a b
- Millionen für so 'n Kamelrennen sind
+ Millionen für so "n Kamelrennen sind
?                  ^

clapton:4> cat c
Millionen deren für so "n Kamelrennen sind
clapton:5> /tmp/ndiff.py -q a c
- Millionen für so 'n Kamelrennen sind
+ Millionen deren für so "n Kamelrennen sind
?           ++++++ -     +

Instead of a - and a subsequent +, I would expect to find here a ^, too.


Follow-Ups:

Date: 2000-Dec-03 19:11
By: tim_one

Comment:
A caret means that the character in the line two above and in the same column was replaced by the character in the line one above and in the same column.  That's why you get a caret in the first example but not the second:  the replacement involves two distinct columns.

If you did get a caret in the second example, where would it go?  If under the single quote from the line two above, it would look the single quote got replaced by the ü in für; if under the double quote from the line one above, like the first e in Kamelrennen got replaced by a double quote.  Both readings would be wrong.

Edit sequences aren't unique, and in the absence of an obvious and non-ambiguous way to show replacements across columns, ndiff settles for a *correct* sequence ("deren " was inserted, "'" was deleted, '"' was inserted).  In this respect ndiff is functioning as designed, so it's not a bug.

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http://sourceforge.net/bugs/?func=detailbug&bug_id=124051&group_id=5470