Re: [PATCH iproute2 v3 1/3] configure: support --param=value style

On Wed, Oct 06, 2021 at 10:09:44AM +0200, Phil Sutter wrote:

Hi Andrea,

A remark regarding coding style:

Hi Phil,
Thanks for your review.

On Wed, Oct 06, 2021 at 12:08:04AM +0200, Andrea Claudi wrote:
[...]

quoted

diff --git a/configure b/configure
index 7f4f3bd9..d57ce0f8 100755
--- a/configure
+++ b/configure

@@ -501,18 +501,30 @@ if [ $# -eq 1 ] && [ "$(echo $1 | cut -c 1)" != '-' ]; then
 else
 	while true; do
 		case "$1" in
-			--include_dir)
-				INCLUDE=$2
-				shift 2 ;;
-			--libbpf_dir)
-				LIBBPF_DIR="$2"
-				shift 2 ;;
-			--libbpf_force)
-				if [ "$2" != 'on' ] && [ "$2" != 'off' ]; then
+			--include_dir | --include_dir=*)

So here the code combines the two cases,

quoted

+				INCLUDE="${1#*=}"
+				if [ "$INCLUDE" == "--include_dir" ]; then

just to fiddle it apart again. Did you consider leaving the old cases in
place and adding separate ones for the --opt=val cases like so:

| 			--include_dir=*)
| 				INCLUDE="${1#*=}"
| 				shift
| 				;;

[...]

That was my first proposal in v1 [1]. I changed it on David's suggestion
to consolidate the two cases into a single one.

Looking at the resulting code, v3 code results in an extra check to
discriminate between the two use cases, while v0 uses the "case"
structure to the same end.

quoted

+			--libbpf_force | --libbpf_force=*)
+				LIBBPF_FORCE="${1#*=}"
+				if [ "$LIBBPF_FORCE" == "--libbpf_force" ]; then
+					LIBBPF_FORCE="$2"
+					shift
+				fi
+				if [ "$LIBBPF_FORCE" != 'on' ] && [ "$LIBBPF_FORCE" != 'off' ]; then

To avoid duplication here, I would move semantic checks into a second
step. This would allow for things like:

| --libbpf_force=invalid --libbpf_force=on

but separating the syntactic parsing from semantic checks might be
beneficial by itself, too.

Yes, I agree with you. David, does this answer to your concern about v1?
If yes, I would proceed with a v4 integrating Phil's suggestions.

Cheers, Phil

[1] https://lore.kernel.org/netdev/cover.1633191885.git.aclaudi@redhat.com/ (local)