Tclers Wiki Forum: Revision history

With WubWiki, it is not yet possible to see the revision history. When changes are made to a page, the whole page is stored on the file systems. More information about the current situation can be found here.

What needs to be done to get revision history:

Decide how to store the revision history.
Decide how to make the revision history accessible to wiki visitors and history wiki gnomes.
Implement all this.

kbk I see that on the cited page that the "old" system of storing pages as CVS checkins is not functioning. That implies that from the time that jcw's system went down until now, we have lacunae in the change history. This is not good.

I do wonder at the comment on the page that "the revision history intermediate storage mechanism is whole-page." Unless you've declared that files are binary (cvs admin -kb), CVS is quite smart about storing the current version together with a set of actions that will reconstitute old versions from the current version. It does not store a complete image of each obsolete page. In fact, I'd be inclined to use CVS (or some other well-qualified revision control system) to manage history simply because it's quite good at what it does. Using the tcllib facilities and building a history mechanism around them strilkes me as needless reinvention of wheels.

Can we develop a set of requirements and discuss where the history system has failed us in the past? If I'm going to implement this (and I might be able to offer up some spare cycles to do so), I'd like to know what constraints I'm playing with.

Posted at May 08/2007 08:38AM:
Colin: The pages are still being written (as whole file pages) but aren't being processed. That's 929 mods to date. So the input part of the old diff system is still functioning. It's quite inefficient, though.

Posted at May 08/2007 08:40AM:
Colin: As to where it's failed us ... given that a diff file needs to be written and committed on every page edit, and given that such a thing gives us not much more than the ability to store and retrieve a patch set, I think the overhead is considerable, nigh unacceptable.

The main effort (given the existence of tcl code working with the tcllib facilities) is to reconstruct some kind of display from a pair of revision numbers yielding an ordered set of patches.

Posted at Jun 28/2007 05:33AM by lvirden:
So, during late May, or early June, this work paid off and the wiki user once again has access to a page's history.

There are several aspects - on the Recent Changes page, each changed page is followed by a greek "delta" character. Clicking on this character takes one to a css colored version of the page, which lines which differ are colored red to indicate a line that was deleted and green to include a line that was added. In mid June 2007, an additional change was added so that clicking on the delta also positions you to the first change on the page.

Another addition to wubwiki was the Revisions link at the bottom of the page.

Posted at Jun 28/2007 05:36AM by lvirden:
One observation - color coding the differences is on a line basis and currently white space is not ignored, so addition of a space, etc. marks a whole line as changed even if no visible text has changed.

Also, access of the delta page via a browser such as lynx makes seeing the change difficult, as it doesn't process external css .

Posted at Jun 28/2007 05:37AM by lvirden:
Two changes that would be nice would be:

1. ignore white space when performing the diff

2. investigate whether there was a way to make use of wdiff or some other mechanism so that more detail regarding the change might be able to be portrayed - for instance, identifying the specific words that were added, deleted, changed, whatever.

Neither of these are high, or even medium, priority changes. They would be just nice touches.