parse-options: move unsigned long option parsing out of pack-objects.c

The unsigned long option parsing (including 'k'/'m'/'g' suffix
parsing) is more widely applicable.  Add support for OPT_MAGNITUDE
to parse-options.h and change pack-objects.c use this support.

The error behavior on parse errors follows that of OPT_INTEGER.  The
name of the option that failed to parse is reported with a brief
message describing the expect format for the option argument and
then the full usage message for the command invoked.

This differs from the previous behavior for OPT_ULONG used in
pack-objects for --max-pack-size and --window-memory which used to
display the value supplied in the error message and did not display
the full usage message.

Signed-off-by: Charles Bailey <cbailey32@bloomberg.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt
index 1f2db31312..525cb2f87a 100644
--- a/Documentation/technical/api-parse-options.txt
+++ b/Documentation/technical/api-parse-options.txt
@@ -168,6 +168,12 @@ There are some macros to easily define options:
 	Introduce an option with integer argument.
 	The integer is put into `int_var`.
 
+`OPT_MAGNITUDE(short, long, &unsigned_long_var, description)`::
+	Introduce an option with a size argument. The argument must be a
+	non-negative integer and may include a suffix of 'k', 'm' or 'g' to
+	scale the provided value by 1024, 1024^2 or 1024^3 respectively.
+	The scaled value is put into `unsigned_long_var`.
+
 `OPT_DATE(short, long, &int_var, description)`::
 	Introduce an option with date argument, see `approxidate()`.
 	The timestamp is put into `int_var`.