Unify annotated and non-annotated tags

Unify annotated and non-annotated tags

[anatoly techtonik]

Hi,

It is hard to work with Git tags, because on low level hash
of non-annotated tag is pointing to commit, but hash for
annotated tag is pointing to tag metadata.

On low level that means that there is no way to get commit
hash from tag in a single step. If tag is annotated, you need
to find and parse ^{} string of show-ref, if not, then look for
string without ^{}.

So, why not just make all tags work the same so that every
tag has its own hash and you need to dereference it in the
same way to get commit hash?

This way I could get all commit hashes with just:

    git show-ref --tags -d | grep "\^{}"

or abandon ^{} completely and show commit hashes on -d:

    git show-ref --tags --dereference

-- 
anatoly t.

Re: Unify annotated and non-annotated tags

[Igor Djordjevic]

Hi Anatoly,

On 10/11/2017 11:58, anatoly techtonik wrote:
> It is hard to work with Git tags, because on low level hash
> of non-annotated tag is pointing to commit, but hash for
> annotated tag is pointing to tag metadata.
> 
> On low level that means that there is no way to get commit
> hash from tag in a single step. If tag is annotated, you need
> to find and parse ^{} string of show-ref, if not, then look for
> string without ^{}.

That is not quite true, as you can always dereference any tag 
(annotated or not) using "<tag>^0" notation, see git-rev-parse[1]:

  "As a special rule, <rev>^0 means the commit itself and is used when 
  <rev> is the object name of a tag object that refers to a commit 
  object."
 
> So, why not just make all tags work the same so that every
> tag has its own hash and you need to dereference it in the
> same way to get commit hash?
> 
> This way I could get all commit hashes with just:
> 
>     git show-ref --tags -d | grep "\^{}"
> 
> or abandon ^{} completely and show commit hashes on -d:
> 
>     git show-ref --tags --dereference
>
Depending on what you would _exactly_ like to do, you could get all 
tagged commit hashes like this:

	git rev-list --tags --no-walk

Note that each commit will be listed only once, even if more tags 
(annotated or not) point to it.

If you would like to mimic output of "git show-ref", repeating 
commits for each tag pointing to it and showing full tag name as 
well, you could do something like this, for example:

	for tag in $(git for-each-ref --format="%(refname)" refs/tags)
	do
		printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
	done


Hope that helps a bit.

Regards, Buga

[1] https://git-scm.com/docs/git-rev-parse#git-rev-parse-emltrevgtemegemHEADv1510em

Re: Unify annotated and non-annotated tags

[Junio C Hamano]

Igor Djordjevic <igor.d.djordjevic@gmail.com> writes:

> If you would like to mimic output of "git show-ref", repeating 
> commits for each tag pointing to it and showing full tag name as 
> well, you could do something like this, for example:
>
> 	for tag in $(git for-each-ref --format="%(refname)" refs/tags)
> 	do
> 		printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
> 	done
>
>
> Hope that helps a bit.

If you use for-each-ref's --format option, you could do something
like (pardon a long line):

git for-each-ref --format='%(if)%(*objectname)%(then)%(*objectname)%(else)%(objectname)%(end) %(refname)' refs/tags

without any loop, I would think.

Re: Unify annotated and non-annotated tags

[Igor Djordjevic]

On 11/11/2017 03:06, Junio C Hamano wrote:

> Igor Djordjevic <igor.d.djordjevic@gmail.com> writes:
> 
>> If you would like to mimic output of "git show-ref", repeating 
>> commits for each tag pointing to it and showing full tag name as 
>> well, you could do something like this, for example:
>>
>> 	for tag in $(git for-each-ref --format="%(refname)" refs/tags)
>> 	do
>> 		printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
>> 	done
>>
>>
>> Hope that helps a bit.
> 
> If you use for-each-ref's --format option, you could do something
> like (pardon a long line):
> 
> git for-each-ref --format='%(if)%(*objectname)%(then)%(*objectname)%(else)%(objectname)%(end) %(refname)' refs/tags
> 
> without any loop, I would think.

... and I did have a feeling it should be possible in a single Git 
command :P Thanks.

Re: Unify annotated and non-annotated tags

[anatoly techtonik]

On Sat, Nov 11, 2017 at 5:06 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Igor Djordjevic <igor.d.djordjevic@gmail.com> writes:
>
>> If you would like to mimic output of "git show-ref", repeating
>> commits for each tag pointing to it and showing full tag name as
>> well, you could do something like this, for example:
>>
>>       for tag in $(git for-each-ref --format="%(refname)" refs/tags)
>>       do
>>               printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
>>       done
>>
>>
>> Hope that helps a bit.
>
> If you use for-each-ref's --format option, you could do something
> like (pardon a long line):
>
> git for-each-ref --format='%(if)%(*objectname)%(then)%(*objectname)%(else)%(objectname)%(end) %(refname)' refs/tags
>
> without any loop, I would think.

Thanks. That helps.

So my proposal is to get rid of non-annotated tags, so to get all
tags with commits that they point to, one would use:

git for-each-ref --format='%(*objectname) %(refname)' refs/tags

For so-called non-annotated tags just leave the message empty.
I don't see why anyone would need non-annotated tags though.
-- 
anatoly t.

Re: Unify annotated and non-annotated tags

[Thomas Braun]

Am 23.11.2017 um 16:08 schrieb Randall S. Becker:

[...]

>> So my proposal is to get rid of non-annotated tags, so to get all
>> tags with commits that they point to, one would use:
>> git for-each-ref --format='%(*objectname) %(refname)' refs/tags>
>> For so-called non-annotated tags just leave the message empty.
>> I don't see why anyone would need non-annotated tags though.

I'm using exclusively non-annotated tags. Why? Because that is the
default of "git tag" and I also, until now, never needed more than
giving a commit a "name".

Many annotated tag messages just repeat the tag name itself, so the
message seems quite redundant to me.

Just my 2 cents,
Thomas

Re: Unify annotated and non-annotated tags

[Junio C Hamano]

anatoly techtonik <techtonik@gmail.com> writes:

>> Git is not doomed to preserve anything forever. We've gradually broken
>> backwards compatibility for a few core things like these.
>>
>> However, just as a bystander reading this thread I haven't seen any
>> compelling reason for why these should be removed. You initially had
>> questions about how to extract info about them, which you got answers
>> to.
>>
>> So what reasons remain for why they need to be removed?
>
> To reduce complexity and prior knowledge when dealing with Git tags.

Then you are barking up a wrong tree, I would have to say.  If you
do not think non-annotated tags are serving any good purpose in the
context of _a_ project you are involved in and making your life
miserable because some tags are and other tags are not annotated,
suggest to _that_ project to refrain from using non-annotated tags.

Projects that do use non-annotated tags have chosen to use them for
reasons of their own.  It may be that these tags could be annotated
tags instead for some projects, and depending on their tooling there
might be no downside in switching.  Or they may have chosen to use
non-annotated tags for reasons that you do not know.

Re: Unify annotated and non-annotated tags

[anatoly techtonik]

On Sat, Nov 11, 2017 at 5:06 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Igor Djordjevic <igor.d.djordjevic@gmail.com> writes:
>
>> If you would like to mimic output of "git show-ref", repeating
>> commits for each tag pointing to it and showing full tag name as
>> well, you could do something like this, for example:
>>
>>       for tag in $(git for-each-ref --format="%(refname)" refs/tags)
>>       do
>>               printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
>>       done
>>
>>
>> Hope that helps a bit.
>
> If you use for-each-ref's --format option, you could do something
> like (pardon a long line):
>
> git for-each-ref --format='%(if)%(*objectname)%(then)%(*objectname)%(else)%(objectname)%(end) %(refname)' refs/tags
>
> without any loop, I would think.

This doesn't work with git 1.9.1
https://github.com/rtfd/readthedocs.org/pull/3441#issuecomment-353567756
When it was added? I searched through GitHub and docs, but can't find any
historical records.

-- 
anatoly t.