Differential RSS feeds

I just refactored my RSS plugin and gave the final touches to the differential feeds as promised.

Differential RSS feeds come in three flavors:

• unified diff: just add ;mode=0 to the feed URL
• summarized htmldiff-alike (;mode=1)
• full-text plus addition/removal info: note that this uses the <ins> and <del> tags, which some RSS readers don't render correctly. Append ;mode=2 to the feed URL to get this.

I've written this with my Ruby 1.9 changelog in mind, whose corresponding feeds would be:

• unified diff
• summarized diff
• full-text plus change info

While I'm at it, here's another feature I didn't show before: you can use some basic feed algebra with eigenclass' feeds, as follows.

http://eigenclass.org/hiki.rb?c=rss;tags=a+b+c

corresponds to the postings matching the a, b and c tags. You can also do

http://eigenclass.org/hiki.rb?c=rss;tags=a,b,c

which matches all entries tagged as a or (inclusive) b or c. finally,

http://eigenclass.org/hiki.rb?c=rss;tags=a+b,c+d,e

is for the articles matching (a AND b) or (c AND d) or e*1.