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Re: Getting hold of the method object currently executed

  Date: Wed, 15 Nov 89 19:18:56 EST
  From: Martin Boyer  <gamin@Moe.McRCIM.McGill.EDU>
  To: kanderso@dino.bbn.com
  Subject: Re: Getting hold of the method object currently executed
  Cc: commonloops@xerox.com
  >   In Victoria Day PCL, is it possible, from the body of a method, to
  >   reference the method object itself?
  > Why do you want this?  Loop optimization?
  Oh no!  I want to be able to "reason" about the method currently being
  executed.  I have added slots to the standard-method class and made
  my methods instances of that new mixin.  I can play with methods as
  objects, but I need the method object to do this.  Hence my query.
So, you want a method to reason about itself while it runs?  The both
versions of the code i sent you returns the effective method.  Is that
what you want?  I don't know how to go from that back to the method to
use its slots from the effective method. 

  >   [...] something like
  >   (get-method generic-function () (mapcar 'find-class arglist))
  >   [...] seems to be a waste of time since, being in the body of a method,
  >   it is obvious that the proper method has just been looked up.
  >   [...]
  > You could just climb up the stack.  Here is Symbolics code:
  > (defun current-function ()
  >   (si:frame-function
  >     (si:frame-previous-active-frame (si:%stack-frame-pointer))))
  > (pcl:defmethod goo (x) (current-function))
  Oops!  I forgot to mention that it has to be portable at least between
  Sun/Lucid and microExplorer.
  If somebody has equivalent hooks for these implementations,
  I'd be eternally grateful.
  >   I tried looking for the call-method macro, but it doesn't seem to exist
  >   in Victoria Day PCL; [...]
  > Here is a portable, but slow way to do it.
  > (defmethod generic-function-effective-method
  >   ((gf standard-generic-function) &rest args)
  >   ;; Returns a function that is the effective method when GF
  >   ;; is applied to ARGS.
  >   (cdr (last (apply #'lookup-method-internal gf
  >                     (generic-function-combined-methods gf)
  > 		    #'car args))))
  Is this faster/better than using the
  (get-method generic-function () (mapcar 'find-class args) nil)
  I proposed earlier?
  Thanks, again, for your kindness,
  PS. Please let me know if this discussion should be carried on a private
  basis instead of bothering everyone on the mailing list with a marginal
I think this is what the list is for.  Everthing is marginal to someone.