No, I am better than that!

Striving to subdue the mediocrity.

1. Rob Brooks-Bilson September 27th, 2006
   18:48 Eastern Daylight Time

   Rick, very nice presentation on LCS. Personally, I’ve always wondered how diffing was handled at an algorithm level. Very clear and concise.
2. Javier November 14th, 2006
   13:58 Eastern Standard Time

   Hey Rick this presentation was great on the algorithm you used for cfdiff. I’ve got cfdiff setup locally and it works great when showing the differences between 2 files. I have noticed though if I make an update for a single line it shows up with a purple background (as it should per the legend) but if I make a minor update in the next line it treats it as a delete and insert rather than an update, why is that?? Is it a bug or something to do with the algorithm itself?? What I mean is instead of seeing a purple background side by side I see red on one side and green on the other indicating a removal and addition.

   What you got here is great thus far and I love what you’ve done. I’ve tried tackling something like this on my own as I’ve seen mediawiki do a great job of implementing it in PHP but man is building a difference engine mind boggling. Will you be having any new updates for your difference engine soon?? I’d love to help out with more testing if you’d like. Email me if you can. I look forward to seeing what else becomes of cfdiff!
3. Rick Osborne November 14th, 2006
   16:13 Eastern Standard Time

   Javier-

   The logic to check for an “update” isn’t in any way intelligent at this time. Really, the LCS algorithm doesn’t account for “updates”, only insertions and deletions. For now, it’s just a single check to see if there was a one-line deletion in the same place as a one-line insertion; it will then convert the pair into an “update”. You could make the logic more intelligent by checking to see if the beginnings and endings of the lines matched, etc, etc, but that’s really just icing on the cake. If you really want to play with it, check out diff.cfc in the AddDifference() function, in the first cfif statement. (Or, if you don’t like the update, you could remove this altogether.)

   I hadn’t planned on releasing any updates any time soon, as I got it working mostly-efficiently for files of up to medium size. I’d like to eventually replace the algorithm with a better one (say, the Four Russians variation or even the snake variation), but neither of those are something that could be done quickly or easily in ColdFusion. This would allow it to process even very large files, but I’m not sure if that’s really a necessity. For what it is used for, mostly viewing CF diffs, there’s not much of a need.

   However, if you have specific needs or bugs, I’d be happy to look at them and work them into the project.

   -R

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