"First of all, current Zend_Feed::findFeeds implementation not only tries to discover available feeds but also parses them and returns a valid Zend_Feed_* instance."
The only reason I suggest that this feature function differently is because HTML files generally offer very few feeds, whereas an OMPL file generally contains many.
"Because Zend_Feed doesn't support OPML at all any OPML support in Zend_Feed::findFeeds will cause Zend_Feed to raise an exception."
Please cite an example of this. As far as I'm aware, this patch works without breaking the existing feature or causing any other conflicts.
"Finally, there's no valid reason to integrate OPML support in Zend_Feed as a syndication flavor."
That's incorrect. Any respectable feed aggregator, web-based or otherwise, offers OMPL import/export as a feature, including Google Reader, Bloglines, and Newsgator/FeedDemon. Don't take my word for it, check the FAQ page for any of those readers and see for yourself.
"OPML is often used as an outline format, for example fo feed collections, and doesn't really fit current Zend_Feed feed format architecture."
That was its original purpose, yes, but it's obviously being used for other things now. See my last comment on feed aggregators using it as an import/export format. I wouldn't say the existing function really "fits" with Zend_Feed, either, so if it's going to have something that doesn't "fit," it may as well be as useful as possible.
I don't think this feature would be a good idea for Zend_Feed.
First of all, current Zend_Feed::findFeeds implementation not only tries to discover available feeds but also parses them and returns a valid Zend_Feed_* instance.
Because Zend_Feed doesn't support OPML at all any OPML support in Zend_Feed::findFeeds will cause Zend_Feed to raise an exception.
Finally, there's no valid reason to integrate OPML support in Zend_Feed as a syndication flavor.
OPML is often used as an outline format, for example fo feed collections, and doesn't really fit current Zend_Feed feed format architecture.