[tor-dev] Tor Export

[Damian Johnson]

> Maybe you could comment on the comments, or at least keep an eye on it

Replied. I clicked watch but I'm not familiar with how github code
reviews work so I might not notice updates.

> Also, I don't suppose you know how to comment on the file, instead of on the diff?

I don't. Personally I do code reviews by pulling their changes and
diffing with where they branched off master. Github's new to me.

> Isn't this a bizarre use-case?  I.e., what is a use-case in which a client wants a csv of a ((ServerDescriptor + ExtraInfoDescriptor) list)?  I.e., a list of a disjoint union type?

Agreed that it's weird which is why we need a test. I'm fine with
having the export function throw a ValueError if it gets mixed
descriptor types.

This issue is something that users of the descriptor reader are likely
to come across. For instance if you point the reader at tor's data
directory then it'll crawl over the cached-descriptors,
cached-extrainfo-descriptors, and cached-consensus, giving you a
generator for each of their contents.

Cheers! -Damian