Does anyone understand why the latter restriction (regarding :export
and :intern) found in the definition of DEFPACKAGE in the hyperspec is
there?
"The collection of symbol-name arguments given to the options :shadow,
:intern, :import-from, and :shadowing-import-from must all be
disjoint; additionally, the symbol-name arguments given to :export and
:intern must be disjoint."
Consider (using Allegro):
CG-USER(9): (defpackage :dino (:use :lisp) (:intern "WILMA"))
#<The DINO package>
CG-USER(10): (find-symbol "WILMA" :dino)
DINO::WILMA
:INTERNAL
CG-USER(11): (export 'dino::wilma :dino)
T
CG-USER(12): (find-symbol "WILMA" :dino)
DINO:WILMA
:EXTERNAL
CG-USER(13): (defpackage :bambam (:use :lisp) (:intern "WILMA")
(:export "WILMA"))
Error: When defining package :BAMBAM, symbol name arguments
given to options :INTERN and :EXPORT must be disjoint. Common
arguments are "WILMA"
[condition type: PROGRAM-ERROR]
If I can export the symbol after I create it using INTERN in
defpackage, why can't I export it using DEFPACKAGE ?
Thanks.
In article <··································@4ax.com>,
JP Massar <······@alum.mit.edu> wrote:
> Does anyone understand why the latter restriction (regarding :export
> and :intern) found in the definition of DEFPACKAGE in the hyperspec is
> there?
>
> "The collection of symbol-name arguments given to the options :shadow,
> :intern, :import-from, and :shadowing-import-from must all be
> disjoint; additionally, the symbol-name arguments given to :export and
> :intern must be disjoint."
To keep it simple. You don't have to check whether a symbol is listed
in multiple options, to determine what's happening with that symbol.
Each symbol is listed in just one place, and that makes it clear
precisely what's going on.
>
> If I can export the symbol after I create it using INTERN in
> defpackage, why can't I export it using DEFPACKAGE ?
Because when you specify :export, it automatically interns it for you.
--
Barry Margolin, ······@alum.mit.edu
Arlington, MA
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