Re: [RFC] stash --continue

[Marc Branchaud <marcnarc@xiplink.com>]

On 2017-01-18 11:34 AM, Johannes Schindelin wrote:
> Hi Marc,
>
> On Wed, 18 Jan 2017, Marc Branchaud wrote:
>
>> On 2017-01-16 05:54 AM, Johannes Schindelin wrote:
>>
>>> On Mon, 16 Jan 2017, Stephan Beyer wrote:
>>>
>>>> a git-newbie-ish co-worker uses git-stash sometimes. Last time he
>>>> used "git stash pop", he got into a merge conflict. After he
>>>> resolved the conflict, he did not know what to do to get the
>>>> repository into the wanted state. In his case, it was only "git add
>>>> <resolved files>" followed by a "git reset" and a "git stash drop",
>>>> but there may be more involved cases when your index is not clean
>>>> before "git stash pop" and you want to have your index as before.
>>>>
>>>> This led to the idea to have something like "git stash
>>>> --continue"[1]
>>>
>>> More like "git stash pop --continue". Without the "pop" command, it
>>> does not make too much sense.
>>
>> Why not?  git should be able to remember what stash command created the
>> conflict.  Why should I have to?  Maybe the fire alarm goes off right when I
>> run the stash command, and by the time I get back to it I can't remember
>> which operation I did.  It would be nice to be able to tell git to "just
>> finish off (or abort) the stash operation, whatever it was".
>
> That reeks of a big potential for confusion.
>
> Imagine for example a total Git noob who calls `git stash list`, scrolls
> two pages down, then hits `q` by mistake. How would you explain to that
> user that `git stash --continue` does not continue showing the list at the
> third page?

Sorry, but I have trouble taking that example seriously.  It assumes 
such a level of "noobness" that the user doesn't even understand how 
standard command output paging works, not just with git but with any 
shell command.

> Even worse: `git stash` (without arguments) defaults to the `save`
> operation, so any user who does not read the documentation (and who does?)
> would assume that `git stash --continue` *also* implies `save`.

Like the first example, your user is trying to "continue" a command that 
is already complete.  It's like try to do "git rebase --continue" when 
there's no rebase operation underway.

Now, maybe there is some way for "git stash save" (implied or explicit) 
to stop partway through the operation.  I can't imagine such a situation 
(out of disk space, maybe?), particularly where the user would expect 
"git stash save" to leave things in a half-finished state.  To me "git 
stash save" should be essentially all-or-nothing.

However, if there were such a partial-failure scenario, then I think it 
would be perfectly reasonable for "git stash --continue" to finish the 
save operation, assuming that the failure condition has been resolved.

> If that was not enough, there would still be the overall design of Git's
> user interface. You can call it confusing, inconsistent, with a lot of
> room for improvement, and you would be correct. But none of Git's commands
> has a `--continue` option that remembers the latest subcommand and
> continues that. To introduce that behavior in `git stash` would disimprove
> the situation.

I think it's more the case that none of the current continuable commands 
have subcommands (though I can't think of all the continuable or 
abortable operations offhand, so maybe I'm wrong).  I think we're 
discussing new UI ground here.

And since the pattern is already "git foo --continue", it seems more 
consistent to me for it to be "git stash --continue" as well. 
Especially since there can be only one partially-complete stash 
sub-operation at one time (per workdir, at least).  So there's no reason 
to change the pattern just for the stash command.

Think of it this way:  All the currently continuable/abortable commands 
put the repository in a shaky state, where performing certain other 
operations would be ill advised.  Attempting to start a rebase while a 
merge conflict is unresolved, for example.  IIRC, git actually tries to 
stop users from shooting their feet in this way.

And so it should be for the stash operation:  If applying a stash yields 
a conflict, it has to be resolved or aborted before something like a 
rebase or merge is attempted.  It doesn't matter which stash subcommand 
created the shaky situation.

In the long run, I think there's even the possibility of generic "git 
continue" and "git abort" commands, that simply continue or abort the 
current partially-complete operation, whatever it is.  (Isn't that the 
ultimate goal of all the "sequencer" work?  I admit I have not been 
following that effort.)

> With every new feature, it is not enough to consider its benefits. You
> always have to take the potential fallout into account, too.

Agreed.

> At least `git stash pop --continue` would be consistent with all other
> `--continue` options in Git that I can think of...

Alas, I disagree!

		M.