threads / discuss / 29991

A better git diff --word-diff (--word-diff-regex) ?

Subject: A better git diff --word-diff (--word-diff-regex) ?

## tl;dr

7 messages between Mar 19, 2012 and Mar 19, 2012.

replies: 6people: 5as markdown or json

Piotr Krukowiecki· Mar 19, 2012, 09:44 UTC · lore
Hi,

is there a way to configure --word-diff to be a more programming language friendly? For example if I add one parameter to a function declaration, I'd like to see only the addition of the parameter as the change. But currently it shows much more.

For example if
  void foo(int x);
is changed to
  void foo(int x, int y);
I'd like to see only ",int y" as the change, not "x, int y);".

I think I'd like to ignore all white spaces and tokenize text on word boundaries and see the diff between the tokens. This way if I e.g. add a missing ";" it'll be shown as the only change.

$ echo 'void foo(int x);' > foo.c && git add foo.c && git commit -m "foo"
[master (root-commit) 5af60cb2] foo
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 foo.c
$ echo 'void foo(int x, int y);' > foo.c && git diff --word-diff
diff --git a/foo.c b/foo.c
index 42a5d4e9..289eb233 100644
--- a/foo.c
+++ b/foo.c
@@ -1 +1 @@
void foo(int [-x);-]{+x, int y);+}


Thanks,

-- 
Piotr Krukowiecki
Matthieu Moy· Mar 19, 2012, 09:47 UTC · re: Piotr Krukowiecki · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

Piotr Krukowiecki <piotr.krukowiecki@gmail.com> writes:
> Hi,
>
> is there a way to configure --word-diff to be a more programming
> language friendly?
I often use this:
  git diff --color-words=.

It's rather bad on plain text, since it will try to diff within words, but works well on source code.

-- 
Matthieu Moy
http://www-verimag.imag.fr/~moy/
Piotr Krukowiecki· Mar 19, 2012, 16:54 UTC · re: Matthieu Moy · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

On Mon, Mar 19, 2012 at 10:47 AM, Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> wrote:

Show 13 quoted lines
> Piotr Krukowiecki <piotr.krukowiecki@gmail.com> writes:
>
>> Hi,
>>
>> is there a way to configure --word-diff to be a more programming
>> language friendly?
>
> I often use this:
>
>  git diff --color-words=.
>
> It's rather bad on plain text, since it will try to diff within words,
> but works well on source code.
Hi,

thanks for the idea, it's surely useful in many cases, but it can look confusing on source code too. For example on git b3256eb8b in path.c one part of the diff is

-                       if (!access(used_path, F_OK)) {
+                       if (!stat(used_path, &st) &&
+                           (S_ISREG(st.st_mode) ||
+                           (S_ISDIR(st.st_mode) &&
is_git_directory(used_path)))) {
and "git diff --word-diff-regex=." shows
                        if (![-acces-]s{+tat+}(used_path, [-F-]{+&st) &&+}
{+                          (S+}_[-OK-]{+ISREG(st.st_mode) ||+}
{+                          (S_ISDIR(st.st_mode) &&
is_git_directory(used_path))+})) {
-- 
Piotr Krukowiecki
Thomas Rast· Mar 19, 2012, 09:50 UTC · re: Piotr Krukowiecki · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

Piotr Krukowiecki <piotr.krukowiecki@gmail.com> writes:
Show 14 quoted lines
> is there a way to configure --word-diff to be a more programming
> language friendly? For example if I add one parameter to a function
> declaration, I'd like to see only the addition of the parameter as the
> change. But currently it shows much more.
>
> For example if
>   void foo(int x);
> is changed to
>   void foo(int x, int y);
> I'd like to see only ",int y" as the change, not "x, int y);".
>
> I think I'd like to ignore all white spaces and tokenize text on word
> boundaries and see the diff between the tokens. This way if I e.g. add
> a missing ";" it'll be shown as the only change.
Umm, what's wrong with
  echo '*.cpp diff=cpp' >>.git/info/attributes

Ok, the funcname patterns aren't so good, but the word regex is designed to "tokenize" as far as that is feasible.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch
Piotr Krukowiecki· Mar 19, 2012, 17:06 UTC · re: Thomas Rast · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

On Mon, Mar 19, 2012 at 10:50 AM, Thomas Rast <trast@student.ethz.ch> wrote:
Show 13 quoted lines
> Piotr Krukowiecki <piotr.krukowiecki@gmail.com> writes:
>
>> is there a way to configure --word-diff to be a more programming
>> language friendly? For example if I add one parameter to a function
>> declaration, I'd like to see only the addition of the parameter as the
>> change. But currently it shows much more.
>
> Umm, what's wrong with
>
>  echo '*.cpp diff=cpp' >>.git/info/attributes
>
> Ok, the funcname patterns aren't so good, but the word regex is designed
> to "tokenize" as far as that is feasible.
Thanks, that's very good! I've missed it reading the git-diff man page.
-- 
Piotr Krukowiecki
Johannes Sixt· Mar 19, 2012, 09:58 UTC · re: Piotr Krukowiecki · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

Am 3/19/2012 10:44, schrieb Piotr Krukowiecki:
Show 14 quoted lines
> is there a way to configure --word-diff to be a more programming
> language friendly? For example if I add one parameter to a function
> declaration, I'd like to see only the addition of the parameter as the
> change. But currently it shows much more.
> 
> For example if
>   void foo(int x);
> is changed to
>   void foo(int x, int y);
> I'd like to see only ",int y" as the change, not "x, int y);".
> 
> I think I'd like to ignore all white spaces and tokenize text on word
> boundaries and see the diff between the tokens. This way if I e.g. add
> a missing ";" it'll be shown as the only change.
Start with
   git config diff.wordregex '[[:alnum:]]+|[^[:space:]]'
Adjust to your likings.
-- Hannes
Jeff King· Mar 19, 2012, 15:10 UTC · re: Piotr Krukowiecki · lore

Re: A better git diff --word-diff (--word-diff-regex) ?

On Mon, Mar 19, 2012 at 10:44:31AM +0100, Piotr Krukowiecki wrote:
Show 10 quoted lines
> is there a way to configure --word-diff to be a more programming
> language friendly? For example if I add one parameter to a function
> declaration, I'd like to see only the addition of the parameter as the
> change. But currently it shows much more.
> 
> For example if
>   void foo(int x);
> is changed to
>   void foo(int x, int y);
> I'd like to see only ",int y" as the change, not "x, int y);".

This does not directly answer your question, but you may want to look at the diff-highlight script in contrib/diff-highlight. I wrote it because I found word-diff often unreadable, but still wanted something to highlight small changes on a line like this.

On your example, it produces:
  -void foo(int x);
  +void foo(int x{+, int y});

except that the {+...} bit is highlighted by color, which makes it quite readable.

-Peff

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