From: Mark Wooding <mdw@distorted.org.uk>
Date: Sat, 4 May 2024 14:42:15 +0000 (+0100)
Subject: defs.m4: Document the behaviour of omitting `KV' apodosis/haeresis args.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/exim-config/commitdiff_plain/3a58bd3cb2cc0ea1054547819356aceba4d8ab11

defs.m4: Document the behaviour of omitting `KV' apodosis/haeresis args.
---

diff --git a/defs.m4 b/defs.m4
index 8be119d..8beb3b1 100644
--- a/defs.m4
+++ b/defs.m4
@@ -169,16 +169,17 @@ m4_define(<:LOOKUP_DOMAIN:>,
 		       _LOOKUP_ARGS(<:$2:>, <:$3:>)}} \
 	     $3:>)
 
-## KV(key, result)
+## KV(key, [result])
 ##
 ## Extract the value of the named KEY in the ${extract ...}-style string in
 ## the current $value (where it may have been left by `LOOKUP-DOMAIN').  The
 ## RESULT is a pair {IF-FOUND}{IF-NOT-FOUND}; the former may use $value to
 ## refer to the value; the latter may be `fail' (not in braces) to force
-## expansion failure.
+## expansion failure.  The default is to expand to the extracted value or
+## nothing.
 m4_define(<:KV:>, <:${extract {$1}{$value}$2}:>)
 
-## DOMKV(key, result)
+## DOMKV(key, [result])
 ##
 ## Extract the value of the named KEY in the ${extract ...}-style string in
 ## $domain_data; see `KV'.