Add alternative using a delimiting character instead of string indexing

SC3057.md

@@ -28,6 +28,25 @@ done
 printf '%s\n' "${argument-}"
 ```
 
+An alternative could be to use a delimiting character instead. For instance, to use texts prefixed with a number, an option is to use a colon as a delimiter and use that in a parameter expansion that removes a pattern form either beginning or ending of variable value:
+
+```sh
+#!/bin/sh
+exitForReasonX='4:Stopping %s because of X.'
+exitForReasonY='6:Stopping because of Y.'
+echo "The ''reason y'' has number '${exitForReasonY#*:}' and its message is: '${exitForReasonY%%:*}'."
+# A more useful example might be :
+reasonableExit ()
+{
+  state="${1:-}"
+  state="${state:?is required}"
+  ${1+shift}
+  >&2 printf '%s\n' "${state%%:*}" ${1+"${@?}"}
+  exit "${state#*:}"
+}
+reasonableExit "${exitForReasonX?}" 'something'
+```
+
 ### Rationale:
 
 String indexing is a bash and ksh extension, and does not work in `dash` or POSIX `sh`.