Re: [Gnu-arch-users] Keeping original file contents in an update

[John A Meinel]

Yaron Minsky wrote:

> A recurrent problem I've had with arch is that by default, after a
> conflict, update leaves a .rej file, which tells you what patches
> didn't apply, and an .orig file, which tells you what the file looked
> like before the attempt to apply your changes.  But what it doesn't
> keep is a version of your files before the update.
>
> To see why this is a problem, consider the case where you have a file
> foo to which you've made extensive changes.  You do an update, to
> discover that someone has made incompatible changes to the same file.
> You're left with a huge .rej file, and no clean way of getting back
> your original file.  (the only way to do that, I think, is to apply
> the ,,undo patch.  But you can't do it on a file-by-file basis, and
> you can't do it at all once you've made other modifications to deal
> with the other rej's.)  So, is there a good solution to this problem?
>  To me, this seems pretty serious, since it can involve loosing data.
>
> (another solution would be to use replay.  But I prefer the semantics
> of update and would rather avoid using replay)
>
> Yaron
I think tla is going to support per-file undo (baz already does with
"baz undo -- file1 file2 ..."). Which might help you here.

Also, you can use "tla library-file"
$ tla library-file -H
find a file in a revision library
usage: tla library-file [options] file revision

 -h, --help     Display a help message and exit.
 -H             Display a verbose help message and exit.
 -V, --version  Display a release identifier string
                and exit.
 -A, --archive  Override `my-default-archive'
 --id           interpret FILE as an inventory id
 --this         interpret FILE as a file within a project tree

Find FILE in REVISION in your revision library and print
its path. If the revision or file is not present, print
an error message and exit with non-0 status.

This will let you get the pristine version of your file. Something like:

cp `tla library-file $file $revision` ,$file

Will put a copy of the file as ",$file" so that you have it for reference.

You can use whatever naming scheme you like. And if you want to
completely reject all changes, you can do:

cp `tla library-file $file $revision` .

Which should replace the current copy with the original copy.

This may only work with revision libraries, and not pristine trees, but
we should have *something* that works with both so that people don't
have to worry about which library format they are using.

John
=:->

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