[darcs-users] darcs patch: make rollback smarter about breaking up changes.

[Eric Kow]

Hi David,

We'd like to pull this patch from your version of darcs.  Any chance you
could explain it to us?  Reinier's review [1] from March was

| This canonizes the patches before rolling them back. While this doesn't
| hurt, I don't see why this is an improvement. Haven't they been
| canonized when they were recorded?  

http://lists.osuosl.org/pipermail/darcs-users/2009-March/018515.html

My superficial guess is that coalescing patches can de-canonise them in
some respect...

On Wed, May 13, 2009 at 12:52:57 +1000, Trent W.Buck wrote:
> A patch from David's branch. It sounds like a good idea, and passes
> our functional tests.  I haven't the faintest idea what it actually
> does, though; would someone who knows what an FL is care to review it?
> 
> Sun Nov 16 08:22:55 EST 2008  David Roundy <droundy at darcs.net>
>   * make rollback smarter about breaking up changes.

Thanks,

Eric

make rollback smarter about breaking up changes.
------------------------------------------------
> David Roundy <droundy at darcs.net>**20081115212255
>  Ignore-this: b822d3d1d1e3263c8cf183fffe754e5a
> ] hunk ./src/Darcs/Commands/Rollback.lhs 45
>                            read_repo, slurp_recorded,
>                            tentativelyMergePatches, withGutsOf,
>                            finalizeRepositoryChanges, sync_repo )
> -import Darcs.Patch ( summary, invert, namepatch, effect, fromPrims, sort_coalesceFL )
> +import Darcs.Patch ( summary, invert, namepatch, effect, fromPrims,
> +                     sort_coalesceFL, canonize )
>  import Darcs.Ordered
>  import Darcs.Hopefully ( n2pia )
>  import Darcs.Lock ( world_readable_temp )
> hunk ./src/Darcs/Commands/Rollback.lhs 127
>                               exitWith ExitSuccess
>         definePatches ps
>         with_selected_last_changes_to_files' "rollback" opts
> -               existing_files (sort_coalesceFL $ effect ps) $ \ (_:>ps'') ->
> +               existing_files (concatFL $ mapFL_FL canonize $
> +                               sort_coalesceFL $ effect ps) $ \ (_:>ps'') ->
>           do when (nullFL ps'') $ do logMessage "No changes selected!"
>                                      exitWith ExitSuccess
>              let make_log = world_readable_temp "darcs-rollback"

-- 
Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow>
PGP Key ID: 08AC04F9
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