WIP: Add RSS Reporter

[ad1217]

This is a work in progress attempt at a RSS reporter. It retrieves job history and compares each version with the previous one to generate a hopefully stable RSS feed.

I have not tested this very thoroughly (it has no tests, but neither do the other reporters) and it is missing documentation, among other things.

I suspect this will either break or be able to be improved once #360 (or equivalent) is merged.

Resolves #53.

[thp]

Would the logic used for --test-diff-filter help there?

[ad1217]

Yup, that's pretty much exactly the same logic. I'm not sure where a method containing that logic could be placed nicely though; it doesn't seem to fit well in either JobBase or JobState.

[thp]

You could make it just another command-line argument instead of a fully-fledged reporter and then you can put it in lib/urlwatch/command.py. A reporter usually only runs when there's a change, but in this case, I could imagine people wanting to export an RSS at some point where everything is already set up (of course, these days, one could use --test-reporter, but that's basically working around the fact that it's not really a reporter, but something meant to be run as command). There can, however, also be a "reporter" in the sense that it would automatically redo the RSS export. So feel free to even create a lib/urlwatch/rss.py and put things there (it's probably fine to use a function from there in the implementation of --test-diff-filter, otherwise put the shared function in e.g. lib/urlwatch/history.py or something).

I would imagine this feature working something like this:

# Export an RSS file, one-off command that exports the full history
urlwatch --export-rss /path/to/something.rss

Plus a reporter that takes as configuration argument at least the filename and will - when enabled - do the RSS export every time a change is detected, basically automating the --export-rss for cases where one has urlwatch running on a server.

In the future (but this can be scoped out of the PR to keep it simple) i'm sure people will want to create separate RSS files for each job of for a subset of jobs, etc... -- this should be easy to add once the basic infrastructure is in, but no need to do it in this PR, imho.

[thp]

Closing due to inactivity.