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Re: [idea] File history tracking hints

Hi Pavel,

On 11/09/2017 09:11, Pavel Kretov wrote:
> Hi all,
> Excuse me if the topic I'm going to raise here has been already discussed
> on the mailing list, forums, or IRC, but I couldn't find anything related.
> The problem:
> Git, being "a stupid content tracker", doesn't try to keep an eye on
> operations which happens to individual files; things like file renames
> aren't recorded during commit, but heuristically detected later.
> Unfortunately, the heuristic can only deal with simple file renames with
> no substantial content changes; it's helpless when you:
>  - rename file and change it's content significantly;
>  - split single file into several files;
>  - merge several files into another;
>  - copy entire file from another commit, and do other things like these.
> However, if we're able to preserve this information, it's possible
> not only to do more accurate 'git blame', but also merge revisions with
> fewer conflicts.
> The proposal:
> The idea is to let user give hints about what was changed during
> the commit. For example, if user did a rename which wasn't automatically
> detected, he would append something like the following to his commit
> message:
>     Tracking-hints: rename dev-vcs/git/git-1.0.ebuild ->
> dev-vcs/git/git-2.0.ebuild
> or (if full paths of affected files can be unambiguously omitted):
>     Tracking-hints: rename git-1.0.ebuild -> git-2.0.ebuild
> There may be other hint types:
>     Tracking-hint: recreate LICENSE.txt
>     Tracking-hint: split main.c -> main.c cmdline.c
>     Tracking-hint: merge linalg.py <- vector.py matrix.py
> or even something like this:
>     Tracking-hint: copy json.py <-
> libs/json.py@4db88291251151d8c5c8e4f20430fa4def2cb2ed
> If file transformation cannot be described by a single tracking hint, it shall
> be possible to specify a sequence of hints at once:
>     Tracking-hint:
>         split Utils.java -> AppHelpers.java StringHelpers.java
>         recreate Utils.java
> Note that in the above example the order of operations really matters, so
> both lines have to reside in one 'Tracking-hint' block.
> * * *
> How do you think, is this idea worth implementing?
> Any other thoughts on this? 

Here[1] you can find Linus` reply (from 2005-04-15) to "rename 
tracking" discussion, usually quoted to explain the Git philosophy on 
this point, even referred to as "one of the most important messages 
in the list archive"[2] by Junio himself.

[1] https://public-inbox.org/git/Pine.LNX.4.58.0504150753440.7211@xxxxxxxxxxxxxxx/
[2] https://public-inbox.org/git/xmqqr30qflk9.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxx/