Re: [PATCH] submodule: spell out API of submodule_move_head
- Date: Mon, 9 Oct 2017 17:55:20 -0700
- From: Jonathan Nieder <jrnieder@xxxxxxxxx>
- Subject: Re: [PATCH] submodule: spell out API of submodule_move_head
Junio C Hamano wrote:
> Jonathan Nieder <jrnieder@xxxxxxxxx> writes:
>> Junio C Hamano wrote:
>>> This is not a new issue (the removed comment did not mention this at
>>> all), but is it correct to say that updates to "index and work tree"
>>> was as if we did "git -C $path checkout new" (and of course, HEAD in
>>> the $path submodule must be at 'old')?
>> I don't understand the question. This comment doesn't say it's like
>> "git checkout" --- are you saying it should?
> No, I am pointing out that this comment does not say what it's like
> clearly enough. s/is it correct/am I correct/ would have been less
> prone to get misunderstood, I guess.
No problem. I think a word or two about how it's like read-tree
in the docstring could be an improvement.
> If it behaves like two-tree "read-tree -m -u", I'd say that the best
> explanation an average developer would understand is that the update
> done to "index and work tree" is like using 'git checkout' to switch
> to the branch whose tip is 'new'.
If it says it's like "git checkout", then I fear that can just lead to
more confusion, since "git checkout" does a number of things (e.g.
updating the HEAD symref) that this function does not do.
It could say that it's like "git reset --keep", I suppose.
>>> What should happen if 'old' does not match reality (i.e. old is NULL
>>> but HEAD does point at some commit, old and HEAD are different,
>>> etc.)? Should the call be aborted?
> ... and that is because?
> When does it make sense to do a two-tree "read-tree -m -u" giving
> the 'old' that is very different from the real 'old' tree-ish that
> corresponds to where your index started at?
Because that is not the purpose of the function.
The caller is responsible for setting 'old' appropriately. A word or
two in that direction would not be a terrible thing.
All that said, I want this function to go away completely. :)
Documenting how it currently behaves is just a good way to understand
what is happening when doing so.