muffle-warning

Restart

Data Arguments Required

None.

Description

This restart is established by warn so that handlers of warning conditions have a way to tell warn that a warning has already been dealt with and that no further action is warranted.

Examples

 (defvar *all-quiet* nil) → *ALL-QUIET* 
 (defvar *saved-warnings* '()) → *SAVED-WARNINGS* 
 (defun quiet-warning-handler (c) 
   (when *all-quiet* 
     (let ((r (find-restart 'muffle-warning c))) 
       (when r 
         (push c *saved-warnings*) 
         (invoke-restart r))))) 
→ CUSTOM-WARNING-HANDLER 
 (defmacro with-quiet-warnings (&body forms) 
   `(let ((*all-quiet* t) 
          (*saved-warnings* '())) 
      (handler-bind ((warning #'quiet-warning-handler)) 
        ,@forms 
        *saved-warnings*))) 
→ WITH-QUIET-WARNINGS 
 (setq saved 
   (with-quiet-warnings 
     (warn "Situation #1.") 
     (let ((*all-quiet* nil)) 
       (warn "Situation #2.")) 
     (warn "Situation #3."))) 
⊳ Warning: Situation #2. 
→ (#<SIMPLE-WARNING 42744421> #<SIMPLE-WARNING 42744365>) 
 (dolist (s saved) (format t "~&~A~%" s)) 
⊳ Situation #3. 
⊳ Situation #1. 
→ NIL