Re: diff.defaultOptions implementation design [was diff.primer]

Peff,

On Fri, 13 Feb 2009, Jeff King wrote:

So I think doing it right is a bit more work in the long run, but the extra 
work is generally improving git.

All that being said, though, I still think we can do the equivalent of 
--no-primer. The trick to avoiding multiple passes is for the option to exist 
outside of the set of primer'd options.

I like the idea of using parse-options to handle diff options and I too would 
like all switches negatable.  I will come back to the other ideas you mention if 
necessary.  You laid it all out nicely.

Assuming we can do away with the switches --[no-]default-options, thereby 
hopefully eliminating the need to accumulate options in any kind of fancy way, 
certainly the right place to "walk" is in diff_setup().  But diff_setup() must 
still ascertain at least one runtime fact: whether or not we are running one of 
the commands that respects default options {diff, log, show}.  Is there an 
elegant way to ascertain that fact from inside diff_setup()?  How do you 
recommend?  (BTW I believe my design achieves this elegantly).

                                       -- Keith