Explain eliminating compiler warnings about undefined variables.

diff --git a/lispref/tips.texi b/lispref/tips.texi
index 3d46466832b286f0ac78d72470fcb835a1abdd9b..c66b71033c24d910bfdcc8302d9374d39d6af3f1 100644 (file)
--- a/lispref/tips.texi
+++ b/lispref/tips.texi
@@ -245,6 +245,17 @@ Lisp, so please don't use it in your programs.  (Emacs uses such names
 only for program-generated buffers.)  The users will find Emacs more
 coherent if all libraries use the same conventions.
 
+@item
+Try to avoid compiler warnings about undefined free variables, by adding
+@cdode{defvar} definitions for these variables.
+
+If you bind a variable in one function, and use it or set it in another
+function, the compiler warns about the latter function unless the
+variable has a definition.  But often these variables have short names,
+and it is not clean for Lisp packages to define such variables names.
+Therefore, you should rename the variable to start with the name prefix
+used for the other functions and variables in your package.
+
 @item
 Indent each function with @kbd{C-M-q} (@code{indent-sexp}) using the
 default indentation parameters.