>   In article <ijeTg.648$RJ3.625@xxxxxxxxxxxx>,
>   Ken Tilton <kentilton@xxxxxxxxx> wrote:
>   
>   Stefan Arentz wrote:
>   I finally got my copy of Practical Common Lisp so I'm going over the first
>   few chapters again. Great stuff but questions keep popping up. I hope this
>   group doesn't mind :-)
>   
>   Here is a simple one. In chapter3 there is the following code
>   
>   (remove-if-not #'evenp (list 1 2 3 4 5))
>   
>   (remove-if-not #'(lambda (x) (= 0 (mod x 2))) (list 1 2 3 4 5))
>   
>   I understand why in the first case #' is used as it is a shortcut for
>   (function 'evenp) right?
>   
>   (remove-if-not 'evenp ...) also works.

There is a subtle difference, I just forget. Something about if the 
function exists when the code gets compiled?

The subtle difference comes up when the function is in a variable and 
the function is redefined after assigning to the variable.

(defvar *test-function-1*)
(defvar *test-function-2*)

(defun test-fun ()
'old)

(setq *test-function-1* 'test-fun)
(setq *test-function-2* #'test-fun)

(defun test-fun ()
'new)

(funcall *test-function-1*) => NEW
(funcall *test-function-2*) => OLD

*TEST-FUNCTION-1* contains the function's name, so it always gets the 
current definition of that name. *TEST-FUNCTION-2* contains the 
function object itself; when function is redefined, a new function is 
created and associated with the name, but this has no effect on 
references to the old function.

- 
Barry Margolin, barmar@xxxxxxxxxxxx
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
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