Re: [PATCH] describe-doc: clarify default length of abbreviation

On Sun, May 16, 2021, at 14:00, Bagas Sanjaya wrote:

On 16/05/21 14.32, Anders Höckersten via GitGitGadget wrote:
  >   --abbrev=<n>::

quoted

-	Instead of using the default 7 hexadecimal digits as the
-	abbreviated object name, use <n> digits, or as many digits
-	as needed to form a unique object name.  An <n> of 0
-	will suppress long format, only showing the closest tag.
+	Instead of using the default number of hexadecimal digits (which
+	will vary according to the size of the repository with a default of
+	7) of the abbreviated object name, use <n> digits, or as many digits
+	as needed to form a unique object name.  An <n> of 0 will suppress
+	long format, only showing the closest tag.
  

I think the more correct is the abbreviated hash length is determined
by number of objects.

I agree. I will modify this to:  "(which will vary according to the number of objects in the repository with a default of 7)" unless you have a different suggestion.

quoted

  --candidates=<n>::
  	Instead of considering only the 10 most recent tags as

@@ -139,8 +140,11 @@ at the end.
  
  The number of additional commits is the number
  of commits which would be displayed by "git log v1.0.4..parent".
-The hash suffix is "-g" + unambiguous abbreviation for the tip commit
-of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`).
+The hash suffix is "-g" + an unambigous abbreviation for the tip commit
+of parent (which was `2414721b194453f058079d897d13c4e377f92dc6`). The
+length of the abbreviation scales as the repository grows, using the
+approximate number of objects in the repository and a bit of math
+around the birthday paradox, and defaults to a minimum of 7.

What is the birthday paradox then?

Also, better say "... and by default the minimum length is 7.".

The explanation was mostly copied from the 2.11.0 release notes, but mentioning the birtday paradox is unnecessary. I suggest changing this sentence to:
"The length of the abbreviation scales as the repository grows using the approximate number of objects in the repository, and by default the minimum length is 7."

Best regards,
Anders