Improve coding conventions for error messages

* doc/lispref/tips.texi (Programming Tips): Clarify coding
conventions for error messages to say that an error message can
start with a Lisp symbol.  (Bug#50658)

diff --git a/doc/lispref/tips.texi b/doc/lispref/tips.texi
index e56ddf3c288a76b3a9c7df296e3464daa7d69b1f..e8f7a3c6bbb0b142db927680c29255e577de142a 100644 (file)
--- a/doc/lispref/tips.texi
+++ b/doc/lispref/tips.texi
@@ -393,7 +393,13 @@ Don't use @code{message}, @code{throw}, @code{sleep-for}, or
 
 @item
 An error message should start with a capital letter but should not end
-with a period.
+with a period or other punctuation.
+
+It is occasionally useful to tell the user where an error originated,
+even if @code{debug-on-error} is nil.  In such cases, a lower-case
+Lisp symbol can be prepended to the error message.  For example, the
+error message ``Invalid input'' could be extended to say
+``some-function: Invalid input''.
 
 @item
 A question asked in the minibuffer with @code{yes-or-no-p} or