[PATCH] Update git-diff documentation

Porcelain documentation should talk in terms of end-user workflow, not
in terms of implementation details.  Do not suggest update-index, but
git-add instead.  Explain differences among 0-, 1- and 2-tree cases
not as differences of number of trees given to the command, but say
why user would want to give these number of trees to the command in
what situation.

Signed-off-by: Junio C Hamano <redacted>
---

 * The same idea as the previous "git commit" documentation.

 Documentation/git-diff.txt |   55 ++++++++++++++++++++++++++++---------------
 1 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/Documentation/git-diff.txt b/Documentation/git-diff.txt
index 228c4d9..8888e0d 100644
--- a/Documentation/git-diff.txt
+++ b/Documentation/git-diff.txt

@@ -12,32 +12,49 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-Show changes between two trees, a tree and the working tree, a
-tree and the index file, or the index file and the working tree.
-The combination of what is compared with what is determined by
-the number of trees given to the command.
+This command shows changes between four combinations of states.
 
-* When no <tree-ish> is given, the working tree and the index
-  file are compared, using `git-diff-files`.
+'git-diff' [--options] [--] [<path>...]::
 
-* When one <tree-ish> is given, the working tree and the named
-  tree are compared, using `git-diff-index`.  The option
-  `--cached` can be given to compare the index file and
-  the named tree.
+	This form is to view the changes you made relative to
+	the index (staging area for the next commit).  In other
+	words, the differences are what you _could_ tell git to
+	further add to the index but you still haven't.  You can
+	stage these changes by using gitlink:git-add[1].
+
+'git-diff' [--options] --cached [<commit>] [--] [<path>...]::
+
+	This form is to view the changes you staged for the next
+	commit relative to the named <tree-ish>.  Typically you
+	would want comparison with the latest commit, so if you
+	do not give <commit>, it defaults to HEAD.
+
+'git-diff' [--options] <commit> -- [<path>...]::
+
+	This form is to view the changes you have in your
+	working tree relative to the named <commit>.  You can
+	use HEAD to compare it with the latest commit, or a
+	branch name to compare with the tip of a different
+	branch.
+
+* 'git-diff' [--options] <commit> <commit> -- [<path>...]
+
+	This form is to view the changes between two <commit>,
+	for example, tips of two branches.
+
+Just in case if you are doing something exotic, it should be
+noted that all of the <commit> in the above description can be
+any <tree-ish>.
 
-* When two <tree-ish>s are given, these two trees are compared
-  using `git-diff-tree`.
 
 OPTIONS
 -------
---diff-options::
-	'--diff-options' are passed to the `git-diff-files`,
-	`git-diff-index`, and `git-diff-tree` commands.  See the
-	documentation for these commands for description.
+include::diff-options.txt[]
 
 <path>...::
-	The <path> arguments are also passed to `git-diff-\*`
-	commands.
+	The <paths> parameters, when given, are used to limit
+	the diff to the named paths (you can give directory
+	names and get diff for all files under them).
 
 
 EXAMPLES

@@ -51,7 +68,7 @@ $ git diff --cached   <2>
 $ git diff HEAD       <3>
 ------------
 +
-<1> changes in the working tree since your last git-update-index.
+<1> changes in the working tree not yet staged for the next commit.
 <2> changes between the index and your last commit; what you
 would be committing if you run "git commit" without "-a" option.
 <3> changes in the working tree since your last commit; what you

-- 
1.4.4.2.g86bd

There were a couple inconsistencies in the formatting of the command
descriptions and a more descriptive initial description is better.

Signed-off-by: Brian Gernhardt <redacted>
---

I agree with Johannes about the original being clearer.  Plus two of
the command examples were missing brackets around -- and one had a
* at the beginning the others didn't.  This patch is against Junio's
changes made on master (1d770), even though his patch didn't apply
cleanly.

Documentation/git-diff.txt |   11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-diff.txt b/Documentation/git-diff.txt
index 534f824..2ba9145 100644
--- a/Documentation/git-diff.txt
+++ b/Documentation/git-diff.txt

@@ -12,7 +12,10 @@ SYNOPSIS

DESCRIPTION
-----------
-This command shows changes between four combinations of states.
+Show changes between two trees, a tree and the working tree, a
+tree and the index file, or the index file and the working tree.
+The combination of what is compared with what is determined by
+the number of trees given to the command.
'git-diff' [--options] [--] [<path>...]::

@@ -25,11 +28,11 @@ This command shows changes between four  

combinations of states.
'git-diff' [--options] --cached [<commit>] [--] [<path>...]::
	This form is to view the changes you staged for the next
-	commit relative to the named <tree-ish>.  Typically you
+	commit relative to the named <commit>.  Typically you
	would want comparison with the latest commit, so if you
	do not give <commit>, it defaults to HEAD.
-'git-diff' [--options] <commit> -- [<path>...]::
+'git-diff' [--options] <commit> [--] [<path>...]::
	This form is to view the changes you have in your
	working tree relative to the named <commit>.  You can

@@ -37,7 +40,7 @@ This command shows changes between four  

combinations of states.
	branch name to compare with the tip of a different
	branch.
-* 'git-diff' [--options] <commit> <commit> -- [<path>...]
+'git-diff' [--options] <commit> <commit> [--] [<path>...]
	This form is to view the changes between two <commit>,
	for example, tips of two branches.
--

On Thu, 14 Dec 2006, Johannes Schindelin wrote:

Hi,

On Thu, 14 Dec 2006, Junio C Hamano wrote:

quoted

-Show changes between two trees, a tree and the working tree, a
-tree and the index file, or the index file and the working tree.
-The combination of what is compared with what is determined by
-the number of trees given to the command.
+This command shows changes between four combinations of states.

I think the old explanation, while longer, is clearer.

It might not if you don't know what a "tree" is in git speak.  The 
notion of what a tree refers to is slowly introduced afterwards which I 
think is better than delivering everything in a dense four lines right 
up front.

Hi,

On Thu, 14 Dec 2006, Junio C Hamano wrote:

-Show changes between two trees, a tree and the working tree, a
-tree and the index file, or the index file and the working tree.
-The combination of what is compared with what is determined by
-the number of trees given to the command.
+This command shows changes between four combinations of states.

I think the old explanation, while longer, is clearer.

I like the rest of your patch, though.

Ciao,

Brian Gernhardt wrote:

-This command shows changes between four combinations of states.
+Show changes between two trees, a tree and the working tree, a
+tree and the index file, or the index file and the working tree.
+The combination of what is compared with what is determined by
+the number of trees given to the command.

You talk here about "number of _trees_" while later you use <commit>,
not <tree> or <tree-ish>. Only at the very end you say that <commit>
(<commit-ish> because you can use tags as well) can be replaced by
any <tree-ish>.

That said, I like this clarification, especially the fact that
I don't have to go to git-diff-tree(1) to find diff options.

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git