From: "René Scharfe" <l.s.r@web.de>
To: Stefan Beller <sbeller@google.com>, gitster@pobox.com
Cc: git@vger.kernel.org
Subject: Re: Rename detection within in files WAS: [PATCH 2/6] t7408: merge short tests, factor out testing method
Date: Sun, 7 Aug 2016 11:24:42 +0200 [thread overview]
Message-ID: <57A6FE5A.9050803@web.de> (raw)
In-Reply-To: <20160805232643.23837-1-sbeller@google.com>
Am 06.08.2016 um 01:26 schrieb Stefan Beller:
> When moving code around, we usually get large chunks of text. If the contributor
> is not 100% trustworthy, we need to review all the code without much intelectual
> joy. Essentially the reviewer is just making sure the parts of the text are the
> same.
>
> I'd like to propose a new addition to the diff format that makes this use case
> easier. The idea is to mark up lines that were just moved around in the file
> instead of adding and removing them.
>
> Currently we have 3 characters that
> are allowed to start a line within a hunk:
> ' ' to indicate context
> '+' to add a line
> '-' to remove a line
>
> I'd propose to add the following characters:
> '*' which is the same as '+', but it indicates that the line was moved
> from somewhere else without change.
> 'X' The same as '-', with the addition that this line was moved to a different
> place without change.
>
> The patch below uses these new '*' and 'X'. Each hunk that makes use of these
> additions, is followed other sections, [moved-from, moved-to] that indicate
> where the corresponding line is.
Interesting idea. It should be easy to convert the result into a regular
unified diff for consumption with patch(1) or git am/apply by replacing
the new flags with + and - and removing the moved-* hunks.
Your example ignores whitespace changes at the start of the line and
within it, the added "-C $working_dir", s/expected/expect/; is this all
intended? Only a single blank line was moved verbatim.
The moved-from and moved-to hunks make this diff quite verbose.
If multiple lines from different sources are moved to the same hunk then
you'd get multiple moved-from hunks following that single destination,
right? (Same with lines moved from a single hunk to multiple
destinations and moved-to.)
But does it even warrent a new format? It's a display problem; the
necessary information is already in the diffs we have today. A
graphical diff viewer could connect moved blocks with lines, like
http://www.araxis.com/merge/ does in its side-by-side view. A
Thunderbird extension (or a bookmarklet or browser extendiion for
webmail users) could do that for an email-based workflow.
Still, what about adding information about moved lines as an extended
header (like that index line)? Line numbers are included in hunk
headers and can serve as orientation. A reader would have to do some
mental arithmetic (ugh), but incompatible format changes would be
avoided. For your example it should look something like this:
move from t/t7408-submodule-reference.sh:52,1
move to t/t7408-submodule-reference.sh:22,1
>
> There are multiple things to tackle when going for such an addition:
> * How to present this to the user (it's covered in this email)
> * how to find the renamed lines algorithmically.
> (there are already approaches to that, e.g. https://github.com/stefanbeller/duplo
> which is http://duplo.sourceforge.net/ with no substantial additions)
>
> Any comments welcome,
>
> Thanks,
> Stefan
>
> ---
> t/t7408-submodule-reference.sh | 50 +++++++++++++++---------------------------
> 1 file changed, 15 insertions(+), 29 deletions(-), 6 moved lines
>
> diff --git a/t/t7408-submodule-reference.sh b/t/t7408-submodule-reference.sh
> index afcc629..1416cbd 100755
> --- a/t/t7408-submodule-reference.sh
> +++ b/t/t7408-submodule-reference.sh
> @@ -10,6 +10,16 @@ base_dir=$(pwd)
>
> U=$base_dir/UPLOAD_LOG
>
> +test_alternate_usage()
> +{
> + alternates_file=$1
> + working_dir=$2
> + test_line_count = 1 $alternates_file &&
> * echo "0 objects, 0 kilobytes" >expect &&
> * git -C $working_dir count-objects >current &&
> * diff expect current
> +}
> +
Post-image line 22.
> test_expect_success 'preparing first repository' '
> test_create_repo A &&
> (
> @@ move-source 42,6 @@ test_expect_success 'that reference gets used with add' '
> test_expect_success 'that reference gets used with add' '
> (
> cd super/sub &&
> X echo "0 objects, 0 kilobytes" > expected &&
> X git count-objects > current &&
> X diff expected current
> )
> '
> @@ -42,44 +52,20 @@ test_expect_success 'preparing superproject' '
> )
> '
>
> -test_expect_success 'submodule add --reference' '
> +test_expect_success 'submodule add --reference uses alternates' '
> (
> cd super &&
> git submodule add --reference ../B "file://$base_dir/A" sub &&
> git commit -m B-super-added
> - )
> -'
> -
Pre-image line 52.
> -test_expect_success 'after add: existence of info/alternates' '
> - test_line_count = 1 super/.git/modules/sub/objects/info/alternates
> -'
> -
> -test_expect_success 'that reference gets used with add' '
> - (
> - cd super/sub &&
> X echo "0 objects, 0 kilobytes" > expected &&
> X git count-objects > current &&
> X diff expected current
> - )
> -'
> -
> -test_expect_success 'cloning superproject' '
> - git clone super super-clone
> -'
> -
> @@ move-to 10,6 @@ test_alternate_usage
> + alternates_file=$1
> + working_dir=$2
> + test_line_count = 1 $alternates_file &&
> * echo "0 objects, 0 kilobytes" >expect &&
> * git -C $working_dir count-objects >current &&
> * diff expect current
> +}
> +
> --
> 2.9.2.572.g9d9644e.dirty
>
prev parent reply other threads:[~2016-08-07 9:24 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-04 19:51 [PATCH 0/6] git clone: Marry --recursive and --reference Stefan Beller
2016-08-04 19:51 ` [PATCH 1/6] t7408: modernize style Stefan Beller
2016-08-05 20:30 ` Junio C Hamano
2016-08-04 19:51 ` [PATCH 2/6] t7408: merge short tests, factor out testing method Stefan Beller
2016-08-05 20:45 ` Junio C Hamano
2016-08-05 22:45 ` Stefan Beller
2016-08-05 23:09 ` Junio C Hamano
2016-08-04 19:51 ` [PATCH 3/6] submodule--helper module-clone: allow multiple references Stefan Beller
2016-08-05 20:54 ` Junio C Hamano
2016-08-04 19:51 ` [PATCH 4/6] submodule--helper update-clone: " Stefan Beller
2016-08-05 19:08 ` Stefan Beller
2016-08-05 21:06 ` Junio C Hamano
2016-08-05 21:19 ` Stefan Beller
2016-08-05 21:31 ` Junio C Hamano
2016-08-05 21:33 ` Stefan Beller
2016-08-04 19:51 ` [PATCH 5/6] submodule update: add super-reference flag Stefan Beller
2016-08-05 21:16 ` Junio C Hamano
2016-08-06 0:22 ` Stefan Beller
2016-08-04 19:51 ` [PATCH 6/6] clone: reference flag is used for submodules as well Stefan Beller
2016-08-05 21:36 ` Junio C Hamano
2016-08-05 19:47 ` [PATCH 0/6] git clone: Marry --recursive and --reference Junio C Hamano
2016-08-05 21:23 ` Stefan Beller
2016-08-05 21:47 ` Junio C Hamano
2016-08-05 23:26 ` Rename detection within in files WAS: [PATCH 2/6] t7408: merge short tests, factor out testing method Stefan Beller
2016-08-07 9:24 ` René Scharfe [this message]
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