[Ecls-list] Arglist?

[Pascal J. Bourguignon]

On 2010/02/11, at 23:04 , szergling wrote:

> On 2/8/10, Juan Jose Garcia-Ripoll <juanjose.garciaripoll at googlemail.com 
> > wrote:
>> ECL does not normally store information about a compiled function  
>> lambda
>> list, just for economy reasons -- it is not used anywhere in ECL,  
>> not even
>> in the debugger because function arguments are directly registered  
>> by the
>> function at run time if debug settings are large enough.
>>
>> If such a function is really needed we would have to add an option  
>> to the
>> compiler so that it stores the lambda list or even the function  
>> code, though
>> the latter would be questionable, given the bloat that would  
>> result.  In any
>> case it would not be that difficult.
>
> Not sure if you all know about this, but clisp does it through
> the declaration mechanism:
>
> http://clisp.cons.org/impnotes/declarations.html#space-decl
>
> I'm not sure if this is better than a dynamic variable, which seems
> more versatile to me, though that's probably because of CL's
> lack of native support for the convenient use (eg temporary
> change to optimization levels) of compilation settings.

Declarations are explicitely extensible in CL, thanks to the  
declaration declaration.

I agree that it would be nice to link keeping meta information to the  
SPACE declaration.  However, if finer declarations are needed, they  
can easily be added.


Eg. assuming:
   (<=>  speed-opt-case-as-table  (and (< 0 speed) (< space 3)))
   (<=>  space-keep-arglist       (< space 3))

we could, if we wanted both the hightest speed optmizations and the  
arglist, declaim:

(declaim (optimize (speed 3)
                    (space 3)
                    (ext:space-keep-arglist)))

so we optimize for speed an space, (therefore not have the case-as- 
table speed optimization), but we keep the argument lists.

Also, the advantage of declarations over global special variables
is that you can specify them easily per object:

(defun %f (a b c)
   (declare (optimize (ext:space-no-keep-arglist))) ; don't keep the  
arglist of
   ...)                                             ; internal  
function whatever
                                                    ; the space  
optimization.

(defun normal-function (a b c)
   ;; will keep or not the arglist depending on global optimize space.
   ...)

(defun external-function (a b c)
    (declare (optimize (ext:space-keep-arglist)))   ; keep the arglist  
of
    ...)                                            ; public functions  
whatever
                                                    ; the space  
optimization.

(Assuming ecl declaimed somewhere:

   (declaim (declaration ext:space-no-keep-arglist ext:space-keep- 
arglist ...))

A file containing this declaim could be provided for inclusion in  
portable programs.
).

-- 
__Pascal Bourguignon__
http://www.informatimago.com