Re: Call Me Gitless

From: Daniel Barkalow <barkalow@iabervon.org>
Date: Aug 18, 2008, 21:31 UTC
Message-ID: <alpine.LNX.1.00.0808181628420.19665@iabervon.org>
In-Reply-To: <7vfxp2m5w8.fsf@gitster.siamese.dyndns.org>

On Mon, 18 Aug 2008, Junio C Hamano wrote:

Show 39 quoted lines

> Daniel Barkalow <barkalow@iabervon.org> writes:
> 
> > On Sun, 17 Aug 2008, Trans wrote:
> >
> >> Well, after a few days of using git, I've decide Linus is too smart to
> >> be designing end-user interfaces.
> >
> > This is true, but hardly relevant. Git's end-user interface was almost 
> > entirely designed by other people, using Linus's excellent 
> > script-developer API.
> 
> I'd agree that you cannot judge Linus's ability to design end-user
> interfaces by observing the UI of git.
> 
> I am pleased to see that almost everybody who responded in this thread has
> refrained from saying meaningless things (aka feeding the troll) to waste
> people's mental bandwidth.
> 
> I think there are three majorly different reasons that new people can get
> confused.
> 
> (1) Some concepts in git are different from what people from other systems
>     are used to.  For example, A new person may be puzzled by the
>     distinction among "git diff", "git diff HEAD" and "git diff --cached"
>     and say "why do you have these three?"
> 
>     Complaining that we have these three instead of two, claiming that
>     such complexity is a source of UI clunkiness, is an invalid argument
>     made by a new person who does not understand the index.  People who do
>     take advantage of the index need the distinction among these three.
>     We shouldn't be doing anything but educate them against that kind of
>     complaints.
> 
>     However, I think it is valid to say, for a person who does not use
>     index very actively (i.e. one who does not incrementally stage), what
>     "git diff" does is confusing.  It does not say anything about new
>     files (until it is modified since added) while showing changes for
>     existing files.  CVS does the same thing ("file foo is a newly added
>     file, no comparison available"), but that may not be a good excuse.

There's another issue here, I think. It's not clear from an understanding of the index, working tree, and commits that the default for "git diff" is between the working tree and the index, as opposed to one of the other possibilities. For most systems, "diff" without options is a preview of what would be in the patch if you were to commit; "git diff", on the other hand, shows what would be left out of the patch. So, even given that people understand the meaning of the index, they can fail to understand what "diff" will tell them. And diff is a bit unhelpful in that it generates headers as for "diff -r a b", regardless of what the things are; if you'd get:

--- (index)/foo/bar +++ ./foo/bar

people would at least be clear on what information they were getting, even if they didn't know why they were getting that as opposed to a different combination.

Show 23 quoted lines

>     If we had a configuration for "index-free" people, that changes the
>     semantics of "git add" to register object name of an empty blob when a
>     new path is added, makes "git add" for existing blobs a no-op, but
>     keeps "git commit -a" and "git commit <paths>" to operate as they
>     currently do, then people with such configuration could:
> 
> 	$ >new-file
>         $ git add new-file
>         $ edit old-file
>         $ edit new-file
>         $ git diff
> 
>     to always see what's the difference from the HEAD is with "git diff",
>     and any of these three:
> 
> 	$ git commit -a
>         $ git commit old-file
>         $ git commit old-file new-file
> 
>     would work as expected by them.  We still need to support the three
>     diff variants for normal git people, but people who do not use index
>     do not have to know the two variants ("git diff" vs "git diff HEAD");
>     such a change could be argued as a "UI improvement" [*1*].

I think that having the possibility of adding an empty blob (or maybe a magical "nothing currently here but git-ls-files includes it") would be preferrable to a no-index mode. That is, the operation that corresponds most directly to "cvs add <filename>" is "git update-index --cacheinfo 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 <filename>", which is not exactly easy to do, and just because a user wants to do this doesn't mean the user doesn't want to use the index; a user that makes extensive use of the index is actually more likely to want the state where a file is tracked but all of the content has not yet been staged.

But we've argued this before.

Show 10 quoted lines

> (2) Some concepts in git are different from what they are used to, without
>     any good reason.  IOW, the concepts have room for improvement, and our
>     UI is based on these faulty concepts.
> 
> (3) Some concepts in git may be exactly the same with other systems, yet
>     our UI may operate differently from them without any good reason.
> 
> I'd be surprised if there is _no_ UI element that falls into the latter
> two categories, but obviously I would not be able to list examples.  If I
> could, they instead would have long been fixed already.

You've got to include the class of "The concepts in git are exactly the same as with other systems (although git also has additional concepts), and commands from other systems do not do the same thing in git (with or without good reason)."

E.g., git has a working directory, and git has a committed state, and CVS has both of these, and "cvs diff" compares the working directory with the committed state, but "git diff" does a different operation.

	-Daniel
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