Re: [PATCH 0/8] fix git-config with duplicate variable entries

On Wed, Nov 21, 2012 at 11:46:33AM -0800, Junio C Hamano wrote:

quoted

The problem is that scripts currently using "--get" are broken by
duplicate entries in include files, whereas internal git handles them
just fine.  Introducing a new switch means that everybody also has to
start using it.

Not exactly.  There are three classes of people:

 - wrote scripts using --get; found out that --get barfs if you feed
   two or more of the same, and have long learned to accept it as a
   limitation and adjusted their configuration files to avoid it.
   They have been doing just fine and wouldn't benefit from this
   series at all.

 - wrote scripts using --get, relying on it barfing if fed zero
   (i.e. missing) or two or more (i.e. ambiguous), perhaps a way to
   keep their configuration files (arguably unnecessarily) clean.
   They are directly harmed by this series.

 - wrote scripts using --get-all and did the last-one-wins
   themselves.  They wouldn't benefit directly from this series,
   unless they are willing to spend a bit of time to remove their
   own last-one-wins logic and replace --get-all with --get (but the
   same effort is needed to migrate to --get-one).

 - wanted to write scripts using --get, but after finding out that
   it barfs if you feed two, gave up emulating the internal, without
   realizing that they could do so with --get-all.  They can now
   write their scripts without using --get-all.

I have a feeling that your cases 2 and 4 do not really exist. Because we
did "last one wins" in the case that it mattered (between different
files), it was always "good enough" to just assume that using "--get"
behaved like git did internally, and nobody really noticed or cared that
we did duplicate detection at all. But that is just from my own
perspective; it is not like I did a complete survey of git-config users.

More compelling to me is that the only ones negatively affected are your
case 2, and that is qualified by the "arguably unnecessary" you wrote.

Everyone else is not negatively impacted, and can later move to using
"--get" if they want to give up any home-grown --get-all code.

quoted

  2. If you are a script that only wants to mimic how get retrieves
     a single value, then this is a bug fix, as it brings "--get" in
     line with git's internal use.

But by definition, no such script exists (if it used "--get", it
didn't mimic the internal in the first place).

They do not exist if we assume that anyone using "--get" carefully
thought about the distinction. But I have the impression that is not the
case, and that they _meant_ to behave just like git, and did not realize
they were not doing so. Even our own scripts are guilty of this.

Yeah, so the only ones that can be harmed is a config lint that uses
the --get option with --file to make sure variables they know must
be single value are indeed so, and they are not doing a thorough
job, unless they are checking across files themselves, at which
point they are better off using --get-all piped to "sort | uniq -c"
or something.  So breakages do not matter much for correctly written
scripts.

Right.

quoted

IOW, I do not see a legitimate use case for this, but see it as an extra
check on broken config.

Yes, I agree with the latter half of that sentence.

So what do we want to do?

-Peff