Hi, I'm trying to learn how ASDF object model works by defining a simple operation "echo-op". I want it to print out pathnames of all loaded lisp files to *standard-output*. It sounds like a simple task, but I couldn't get it to work. Thus I'm asking for help here. To do that, I define a project: ----------- file: echo-op.asd ------------------- (defsystem #:echo-op :components ((:file "package") (:file "echo-op"))) ------------------------------------------------- ----------- file: package.lisp ------------------- (defpackage #:echo-op (:use #:cl #:asdf) (:export #:selfward-echo-op)) ------------------------------------------------- ----------- file: echo-op.lisp ------------------- (in-package #:echo-op) (defclass selfward-echo-op (selfward-operation) ()) (defmethod asdf:component-depends-on ((op selfward-echo-op) c) `((selfward-echo-op ,c) ,@(call-next-method))) (defmethod asdf:output-files ((op selfward-echo-op) c) nil) (defmethod asdf:perform :around ((op selfward-echo-op) c) (let ((input-files (asdf:input-files op c))) (loop for file in input-files do (format t "~s" file)))) (setf (find-class 'asdf::selfward-echo-op) (find-class 'selfward-echo-op)) ------------------------------------------------- Then, if I run these from the REPL: ----------- REPL ------------------- CL-USER> (asdf:load-system :echo-op :force t) ; compiling file ; compilation finished in 0:00:00.004 ; compiling file ; wrote ; compilation finished in 0:00:00.036 T CL-USER> (asdf:operate 'asdf::selfward-echo-op :echo-op-test) ; Evaluation aborted on #<SB-PCL::NO-APPLICABLE-METHOD-ERROR {1002341273}>. ------------------------------------------------- I got the error: ----------- SLIME *sldb* ------------------- The slot ASDF/ACTION:SELFWARD-OPERATION is unbound in the object #<SELFWARD-ECHO-OP >. [Condition of type UNBOUND-SLOT] ------------------------------------------------- The "echo-op-test" system is simply: ----------- file: echo-op-test.lisp ------------------- (defsystem #:echo-op-test :defsystem-depends-on (#:echo-op) :components ((:file "package") (:file "example") (:file "main"))) ------------------------------------------------- with empty files package.lisp, example.lisp, and main.lisp. Now, if I redefine selfward-echo-op to subclass load-op, I got this error instead: ----------- SLIME *sldb* ------------------- Circular dependency of #1=(#<ECHO-OP:SELFWARD-ECHO-OP > . #<ASDF/SYSTEM:SYSTEM "echo-op-test">) on: (#1#) [Condition of type ASDF/ACTION:CIRCULAR-DEPENDENCY] ------------------------------------------------- which I have no idea what is going on. I'm still learning about ASDF, so any help to achieve what I want to do would be very much appreciated. Thanks! -- Regards, zacque