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wed 2026-10-07 18:13 UTC

[PATCH v2 1/3] contrib/subtree: reduce function side-effects

From
CSColin Stagner <ask+git@howdoi.land>
Date
Mar 5, 2026, 23:55 UTC
Message-ID
<20260305-cs-subtree-split-recursion-v2-1-7266be870ba9@howdoi.land>
In-Reply-To
<20260305-cs-subtree-split-recursion-v2-0-7266be870ba9@howdoi.land>

`process_subtree_split_trailer()` communicates its return value to the caller by setting a variable (`sub`) that is also defined by the calling function. This is both unclear and encourages side-effects.

Invoke this function in a sub-shell instead.
Signed-off-by: Colin Stagner <ask+git@howdoi.land>
---
 contrib/subtree/git-subtree.sh | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 791fd8260c..bae5d9170b 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -373,6 +373,10 @@ try_remove_previous () {
 }
 
 # Usage: process_subtree_split_trailer SPLIT_HASH MAIN_HASH [REPOSITORY]
+#
+# Parse SPLIT_HASH as a commit. If the commit is not found, fetches
+# REPOSITORY and tries again. If found, prints full commit hash.
+# Otherwise, dies.
 process_subtree_split_trailer () {
 	assert test $# -ge 2
 	assert test $# -le 3
@@ -400,6 +404,7 @@ process_subtree_split_trailer () {
 			die "$fail_msg"
 		fi
 	fi
+	echo "${sub}"
 }
 
 # Usage: find_latest_squash DIR [REPOSITORY]
@@ -432,7 +437,7 @@ find_latest_squash () {
 			main="$b"
 			;;
 		git-subtree-split:)
-			process_subtree_split_trailer "$b" "$sq" "$repository"
+			sub="$(process_subtree_split_trailer "$b" "$sq" "$repository")" || exit 1
 			;;
 		END)
 			if test -n "$sub"
@@ -489,7 +494,7 @@ find_existing_splits () {
 			main="$b"
 			;;
 		git-subtree-split:)
-			process_subtree_split_trailer "$b" "$sq" "$repository"
+			sub="$(process_subtree_split_trailer "$b" "$sq" "$repository")" || exit 1
 			;;
 		END)
 			debug "Main is: '$main'"
-- 
2.43.0
Next: Colin Stagner
Message 1 of 22 in “contrib/subtree: reduce function side-effects”
  1. 1/3 contrib/subtree: reduce function side-effectsColin Stagner, Mar 5, 2026
  2. 2/3 contrib/subtree: functionalize split traversalColin Stagner, Mar 5, 2026
  3. 3/3 contrib/subtree: reduce recursion during splitColin Stagner, Mar 5, 2026
  4. 0/3 contrib/subtree: reduce recursion during splitColin Stagner, Mar 5, 2026
  5. Junio C HamanoMar 13, 2026
  6. Junio C HamanoMar 13, 2026
  7. Junio C HamanoApr 15, 2026
  8. Ben KnobleApr 15, 2026
  9. Ian JacksonApr 16, 2026
  10. Junio C HamanoApr 16, 2026
  11. Colin StagnerApr 17, 2026
  12. Ian JacksonApr 19, 2026
  13. Ben KnobleApr 20, 2026
  14. Junio C HamanoApr 20, 2026
  15. Ian JacksonApr 20, 2026
  16. Colin StagnerApr 21, 2026
  17. Johannes SchindelinApr 22, 2026
  18. git-subtree rewriteIan Jackson, Apr 22, 2026
  19. Junio C HamanoJun 1, 2026
  20. Ian JacksonJun 2, 2026
  21. Colin StagnerJun 3, 2026
  22. Ian JacksonJun 3, 2026

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