On 01/30/2012 07:48 PM, Junio C Hamano wrote:
> Michael Haggerty <mhagger@xxxxxxxxxxxx> writes:
>
>> [3] If commit 0000000 were treated specially, then there would be no
>> unborn branches but only branches pointing at the empty commit. In that
>> case, my expectation would change--the old branch should be left
>> pointing at 0000000. But currently git has no concept of an unborn
>> branch that is not HEAD.
>
> And it probably is not a good thing to add such. Under that constraints,
> HEAD that says refs/heads/foo where foo does not exist yet needs to be
> special cased at places where it matters.
>
> For that matter, even if we artificially created refs/heads/foo before any
> commit is made and made it point at 0{40}, you would need to add special
> cases to other parts of the system
No, the idea is to avoid special casing by making 0{40} into a real (but
empty) revision.
> (e.g. "commit" needs to notice that the
> result should be a root, not a child of 0{40};
No, commits that were previously generated as orphans *would* now be
generated as children of the special 0{40} commit.
> "checkout other_branch"
> needs to notice that it should refrain from running the equivalent of
> "read-tree -m HEAD other_branch" because HEAD does not point at a real
> tree;
No, it would merge the 0{40} commit with other_branch like usual,
resulting in the same contents as other_branch. Indeed, if other_branch
is also ultimately a descendant of 0{40}, this would be like a
fast-forward merge.
> etc.
This "etc" might include problems.
> so it does not change the fact that the unborn branch is case
> is special.
On the contrary, I believe that much special casing could be eliminated
and the UI made more uniform by treating everything as a descendant of a
special "NULL" commit.
Michael
--
Michael Haggerty
mhagger@xxxxxxxxxxxx
http://softwareswirl.blogspot.com/
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