Subject: Re: Macro question (bizarre)
From: Erik Naggum <>
Date: 2000/03/18
Newsgroups: comp.lang.lisp
Message-ID: <>

* Tom Breton <>
| Pardon my opinion, but multiple values are basically for when you have
| code set in stone...

  noted as opinion.

| IOW, values is basically a backwards-compatibility thing.

  it can definitely be used for this purpose, and may even have great value
  used this way, but I must admit that I never thought of values like that.

  values to me is a mechanism that removes the burden of agreeing on the
  aggregate form of the returned values.  I guess this has to be explained
  in terms of how other languages deal with the same issue: multiple values
  are often expressed in C by passing a pointer to a structure in the
  caller's memory to be filled in by the callee.  returning a structure is
  _still_ not kosher in the C world, and incompatibilities exist in how it
  is done.  this affects how people return more than one value from their
  functions.  in some cases, the caller needs to pass multiple pointers as
  arguments to be written to.  Ada has a clean way to do this: with in and
  out arguments, the latter of which act just like multiple-value-setq.

| When that's *not* the case, simply returning a list is better in every
| way that springs to mind, IMO.

  since consing and destructuring both have very significant costs, I'd
  rate this is an insufficiency of things that spring to mind.