Subject: Re: Stupid lexicon tricks
From: (Rob Warnock)
Date: Sat, 23 Feb 2008 23:34:35 -0600
Newsgroups: comp.lang.lisp
Message-ID: <>
<> wrote:
| I would like to define a package that defines values of physics
| constants.  I would than import some of these constants into my
| working package.  But I would like to rename the constants.
| For example, suppose I have a constant defined as *speed-of-light* in
| the :physics-constants package.  But that is long and overly
| descriptive, and in my working package I would like to use "c".
| Now I guess I could write a macro wrapper to use-package when it comes
| to importing variables from my physics-constants package.  (Or maybe
| package is overkill for my purpose.  I could use some kind of hash and
| rename on the fly.)

Ouch! That sounds way too heavyweight for simple renaming of a few
constants. What about just using DEFINE-SYMBOL-MACRO? E.g.:

    (define-symbol-macro +c+ physics-constants:+speed-of-light+)

Note: Just as *...* is conventionally used for special variables
(DEFVAR/DEFPARAMETER), +...+ is the CL convention for constants
(DEFCONSTANT). Though calling it simply "C" probably isn't an issue
in this case, since names defined with DEFINE-SYMBOL-MACRO *can* be
lexically rebound with LET or SYMBOL-MACROLET. [Names defined with


Rob Warnock			<>
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