Re: throw vs. return-from - Naggum cll archive

Subject: Re: throw vs. return-from
From: Erik Naggum <erik@naggum.no>
Date: 1999/06/20
Newsgroups: comp.lang.lisp
Message-ID: <3138861886228801@naggum.no>

* Kent M Pitman <pitman@world.std.com>
| All other things being equal, I'd advocate fixing this.  But the expense
| of changing the standard is so high that likely the changes you'll see in
| the future will ber layerings, not corrections.  Still, we'll see.
| That's just a guess on my part, not anyone's policy statement.

  hm?  how would making an argument optional be expensive?  it seems like
  it's a trivial thing to do, while, say, adding a required argument would
  be expensive.  perhaps I'm misled by the work required to make it work
  that way in a conforming Common Lisp system:

(shadowing-inport 'cl:throw)
(defmacro throw (tag-form &optional result-form)
  `(cl:throw ,tag-form ,result-form))

#:Erik
-- 
@1999-07-22T00:37:33Z -- pi billion seconds since the turn of the century