Re: Issue: IGNORE-VARIABLE (Version 1)

[franz!frisky!jkf@ucbarpa.Berkeley.EDU (John Foderaro)]

>> One good metric of whether it is a good programming practice is whether
>> it ever leads to trouble. Do you ...
>>
>>  - have any instances of real code that uses IGNORE where you felt
>>    the writer's intent would have been clearer if he'd done something else?

 I'm sure that if you gave me access to source code where 'ignore' was
used,  I could find plenty of examples where it shouldn't have been.
Since I don't have that access, I looked in the pcl code (not to pick
on pcl, but it was all that I had):

 from 3600-low.cl:

(defun set-function-name-1 (fn new-name ignore)
  (cond ((or (funcallable-instance-p fn)
	     (si:lexical-closure-p fn))
 
  So set-function-name-1 takes three arguments, what is the third
  argument?   Suppose I want to rewrite set-function-name-1, maybe I'll 
  need this variable when I rewrite it.  

Here is how it should be written (sure it takes more keystrokes
but it is worth it):  

 from coral-low.cl:

(defun set-function-name-1 (function new-name uninterned-name)
  (declare (ignore uninterned-name))
  (cond ((ccl::lfunp function)

  
 from macros.cl:

(defmacro destructuring-bind (pattern form &body body)
  (multiple-value-bind (ignore declares body)
      (extract-declarations body)

 again, the question the reader of this code has is what the first
value returned by extract-declarations?