Subject: Re: How to undo previously set configuration? (again)

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Wed, 01 May 2019 14:18:34 +0200

On Wed, May 01 2019, Duy Nguyen wrote:

> On Wed, May 1, 2019 at 4:14 AM Jeff King <[email-masked]> wrote:
>> It's definitely not implemented universally; each consumer of the config
>> option must decide on it (and it will probably always be that way to
>> some degree, since we don't know the semantics of each options; recall
>> that we may be holding config keys for other non-core programs, too).
>> And we just haven't retro-fitted a lot of those older options because
>> nobody has been bothered by it.
>>
>> That said, I am a proponent of having some kind of clearing mechanism
>> (and I was the one who added credential.helper's mechanism, which has
>> been mentioned in this thread).  I think it makes things a lot less
>> difficult if we don't have to change the syntax of the config files to
>> do it. With that constraint, that pretty much leaves:
>>
>>   1. Some sentinel value like the empty string. That one _probably_
>>      works in most cases, but there may be lists which want to represent
>>      the empty value. There could be other sentinel values (e.g.,
>>      "CLEAR") which are simply unlikely to be used as real values.
>>
>>   2. The boolean syntax (i.e., "[foo]bar" with no equals) is almost
>>      always bogus for a list. So that can work as a sentinel that is
>>      OK syntactically.
>
> Another question about the universal clearing mechanism, how does "git
> config" fit into this? It would be great if the user can actually see
> the same thing a git command sees to troubleshoot. Option 1 leaves the
> interpretation/guessing to the user, "git config" simply gives the raw
> input list before "clear" is processed. Option 2, "git config"
> probably can be taught to optionally clear when it sees the boolean
> syntax.

We can make it fancier, but we already deal with this, e.g. if you do
"git config -l" we'll show "include{,if}" directives at the same "level"
as other "normal" keys.

We also provide no way in "git config" to properly interpret a
value. E.g. does a "user.email" showing up twice for me mean I have two
E-Mails at the same time, or does the last one win? We both know the
answer, but git-config itself doesn't, and that information lives in
docs/code outside of it.

Similarly we'd just print a sequence of:

    user.name=foo
    user.email=bar
    exclude.key=user.*
    user.name=baz

And it would be up to some "smarter" reader of the config data to
realize that the end result is one where we have no "user.email" set,
and "user.name=baz".

But yeah, optionally having some new --list-normalized or
--list-after-excludes or whatever would be great, and presumably not
hard if we had some central "excludes" mechanism...