Re: When not to use subdiff

I ran into some surprising output one of the first times I used ccdiff after getting back to work this week:

-         <ds:KeyName>foo.work.se</ds:KeyName>
-                        ^^^^^^^ ^^^ ^^^^^^^^^
-         <ds:KeyName>splat.work.se</ds:KeyName>
- ^^^^^^^^^^^^^^^^^^^^^^^^                        
+         <ds:KeyName>foo-test.work.se</ds:KeyName>
+                        ^^
[download]

Took me a minute to figure out that it was seeing the diff as "up to 'foo' from the first line, then insert '-t', grab an 'e' and an 's' from later in the first line, and finally take everything starting with 't' on the second line" rather than "insert '-test' on the first line and drop the second line entirely".

Probably another good case for a "percentage of changed characters is over x%" check.

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Re^2: When not to use subdiff by Tux (Canon) on Aug 25, 2018 at 09:10 UTC
Agree. It stands out way better with `-r` and colors, but still. I've added the files to my sandbox. Note that this is still beyond the scope of where I created it for, but I will not ignore this feedback. Enjoy, Have FUN! H.Merijn	[reply] [d/l]
Re^2: When not to use subdiff by Tux (Canon) on Aug 25, 2018 at 12:00 UTC
Could you pull from the git repo and try again with `-h20`. You can find what is your intuitive limit and put `heuristics : 20` in `~/.config/ccdiff`. As I got no other suggestions in this thread, I implemented both suggestions. Enjoy, Have FUN! H.Merijn	[reply] [d/l] [select]
Re^3: When not to use subdiff by dsheroh (Monsignor) on Aug 26, 2018 at 08:53 UTC
With `-h20` I get: `- <ds:KeyName>foo.work.se</ds:KeyName> - <ds:KeyName>splat.work.se</ds:KeyName> + <ds:KeyName>foo-test.work.se</ds:KeyName>` [download] So I experimented a bit with other heuristic values, trying to find a setting which would give me `- <ds:KeyName>foo.work.se</ds:KeyName> + <ds:KeyName>foo-test.work.se</ds:KeyName> + ^^^^^ - <ds:KeyName>splat.work.se</ds:KeyName>` [download] and found that I get the "classic" diff output for values in the range 2-49, with heuristic values of 1 or 50+ reverting to the original output. Since `ccdiff -h` describes `-h n` as "Horizontal char diff treshold"¹, I'm guessing that's because the smallest chunks taken in the original output are 1 character, while the complete line (with the real hostname) is 50 characters. Is that a correct description of how the heuristic works or is it just a coincidence? ¹ When I pasted that, my spellcheck caught a typo in "treshold" - it's missing an "h".	[reply] [d/l] [select]
Re^4: When not to use subdiff by Tux (Canon) on Aug 26, 2018 at 08:58 UTC
Typo fixed (thanks) -h1 was an off-by-one error. Also fixed. Pushed Thanks for the feedback Enjoy, Have FUN! H.Merijn	[reply]