Brad,
Thanks for your feedback.
On 03/10/2014 06:03 PM, Brad King wrote:
> On 03/10/2014 08:46 AM, Michael Haggerty wrote:
>> This test is trying to test a few ways to delete references using "git
>> update-ref -z --stdin". The third line passed in is
>>
>> update SP /refs/heads/c NUL NUL <sha1> NUL
>>
>> , which is not a correct way to delete a reference according to the
>> documentation (the new value should be zeros, not empty). Pass zeros
>> instead as the new value to test the code correctly.
>
> In my original work on this feature, an empty <newvalue> is allowed.
> Since newvalue is not optional an empty value can be treated as zero.
> The relevant documentation is:
>
> update::
> Set <ref> to <newvalue> after verifying <oldvalue>, if given.
> Specify a zero <newvalue> to ensure the ref does not exist
>
> ...
>
> Use 40 "0" or the empty string to specify a zero value, except that
> with `-z` an empty <oldvalue> is considered missing.
>
> The two together say that <newvalue> can be the empty string instead
> of a literal zero.
OK, with your explanation and after reading the docs a couple more
times, I can see your reading. Your rules as I now understand them:
* Without -z
* 0{40} or the empty string represents zeros
* No preceding SP delimiter indicates that the value is missing
(as are any following values)
* With -z
* For <newvalue>
* 0{40} or the empty string represents zeros (the value is
not allowed to be missing)
* For <oldvalue>
* 0{40} represents zeros
* The empty string indicates that the value is missing
I implemented the slightly simpler rules
* Without -z
* 0{40} or the empty string represents zeros
* No preceding delimiter indicates that the value is missing (as
are any following values)
* With -z
* 0{40} represents zeros
* The empty string indicates that the value is missing
It seems to me that "-z" input will nearly always be machine-generated,
so there is not much reason to accept the empty string as shorthand for
zeros. So I think that my version of the rules, being simpler to
explain, is a slight improvement. But your version is already out in
the wild, so backwards-compatibility is also a consideration, even
though it is rather a fine point in a rather unlikely usage (why use
update rather than delete to delete a reference?).
I don't know. I'm willing to rewrite the code to go back to your rules,
or rewrite the documentation to describe my rules.
Neutral bystanders *cough*Junio*cough*, what do you prefer?
Michael
--
Michael Haggerty
mhagger@xxxxxxxxxxxx
http://softwareswirl.blogspot.com/
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