rev-list docs: clarify --topo-order description

It was unclear what "--topo-order" was really about in the
documentation.  It is not just about "children before parent", but
also about "don't mix lineages".

Reword the description for both "--date-order" and "--topo-order",
and add an illustration to it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 6a4b6355ba91d60ebf2279903a25032256f2063b..9404d08673630d21c1394bdd4b5e3c3af6334b08 100644 (file)
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -578,16 +578,33 @@ Commit Ordering
 
 By default, the commits are shown in reverse chronological order.
 
---topo-order::
+--date-order::
+       Show no parents before all of its children are shown, but
+       otherwise show commits in the commit timestamp order.
 
-       This option makes them appear in topological order (i.e.
-       descendant commits are shown before their parents).
+--topo-order::
+       Show no parents before all of its children are shown, and
+       avoid showing commits on multiple lines of history
+       intermixed.
++
+For example, in a commit history like this:
++
+----------------------------------------------------------------
 
---date-order::
+    ---1----2----4----7
+       \              \
+        3----5----6----8---
 
-       This option is similar to '--topo-order' in the sense that no
-       parent comes before all of its children, but otherwise things
-       are still ordered in the commit timestamp order.
+----------------------------------------------------------------
++
+where the numbers denote the order of commit timestamps, `git
+rev-list` and friends with `--date-order` show the commits in the
+timestamp order: 8 7 6 5 4 3 2 1.
++
+With `--topo-order`, they would show 8 6 5 3 7 4 2 1 (or 8 7 4 2 6 5
+3 1); some older commits are shown before newer ones in order to
+avoid showing the commits from two parallel development track mixed
+together.
 
 --reverse::