Custom Query (1030 matches)

The following code signals an error about the :sign keyword argument. The culprit seems to be the method on T, which prevents the method on list to run. If I omit the method on T, or I define it e.g. on built-in-class, the error is gone.

(defgeneric render (obj &rest args))

(defmethod render ((obj t) &key)
  (print obj))

(defmethod render ((obj list) &rest args)
  (mapc (lambda (item)
          (apply #'render item args))
        obj))

(defmethod render ((obj number) &key sign)
  (print (* sign obj)))

(render (list 1 2 3 4) :sign -1)

According to my reading of CLHS (7.6.4 & 7.6.5), no error should be signaled. Indeed, I have tested this with SBCL and it runs just fine.

Welcome to Clozure Common Lisp Version 1.10-dev-r15846M-trunk  (DarwinX8664)!
? (directory #P"~/directory-with-one-subdirectory/**/")
> Error: The value NIL is not of the expected type STRUCTURE.
> While executing: CCL::%PROCESS-DIRECTORY-RESULT, in process Listener(4).
> Type cmd-. to abort, cmd-\ for a list of available restarts.
> Type :? for other options.
1 > 

This used to work.

Welcome to Clozure Common Lisp Version 1.10-dev-r15778M-trunk  (DarwinX8664)!
? (directory #P"~/directory-with-one-subdirectory/**/")
(#P"/Users/alms/directory-with-one-subdirectory/" #P"/Users/alms/directory-with-one-subdirectory/the-one-subdirectory/")
? 

(defun f () (setf (symbol-function 'f) (lambda () 1)) (f))

Such a function will cause an infinite loop when it is call at first time but when interupting and calling (f) again, it has been modified to (lambda () 1) I have tried several CL implementation and they all behave correctly, they return 1 and do not cause an infinite loop.