Don't accept code from strangers

Or, this message will go to bogus

I should have done what the manual says: 6.4.6 Fancy Mail Splitting

For years, at least since 2008, but likely far longer, I’ve been splitting my mail building on someone else’s code that I got on the Internet. It worked, but it had a few quirks that I had not really noticed.

There’s a big difference between

"INBOX"))

and

("INBOX" "")))

placed at the end of

(setq nnimap-split-fancy
      '(|
      ("subject" "media alert" "INBOX.pressreleases")      
      [...]  snipped many lines
      (: (lambda ()
      (car (bbdb/gnus-split-method))))
      ;; Default mailbox
      "INBOX"))

Determined Adam Sjøgren encouraged me to edebug my nnimap-split-fancy code (see nnmail-mail-splitting-decodes). The manual is always right. In my defence, I’d like to say, “You can’t understand the manual, until you do.”

The code I took from a stranger comes with “”, and adds an extra pair of ().

Having both, doing gnus-summary-respool-trace (B t) on unsplitable messages will return:

(: (lambda nil (car (bbdb/gnus-split-method))))
message will go to mail.misc

Removing the "" while keeping the equally superfluous (), B t will return:

(: (lambda nil (car (bbdb/gnus-split-method))))
message will go to bogus

When removing both, following the example in the manual, B t will return:

(: (lambda nil (car (bbdb/gnus-split-method))))
message will go to INBOX

Which is cleaner: my IMAP folder collection includes neither mail.misc nor bogus, but an INBOX it has.