From: pjb@informatimago.com (Pascal J. Bourguignon)
To: help-gnu-emacs@gnu.org
Subject: Re: Emulating namespaces
Date: Thu, 03 Jun 2010 11:26:06 +0200 [thread overview]
Message-ID: <87typksc0h.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: e73e123d-3f0c-4a6f-bbac-b91fb71bf07d@f14g2000vbn.googlegroups.com
LanX <lanx.perl@googlemail.com> writes:
> I was meditating about how namespaces are realized in perl and now I'm
> wondering if this behaviour could be mimicked in elisp.
Actually, emacs has already the primitive mechanism needed to
implement packages. This can AFAIK be done entirely in emacs lisp.
If only it had reader macros, we could provide the pack::sym and
pack:sym syntax too (and correct the :keyword syntax).
Emacs lisp stores symbols in obarrays. The variable obarray is used
by intern, mapatom, etc.
So, basically:
(defvar *package-name-map* (make-hash-table :test (function equal)))
(defvar *list-all-packages* '())
(defun list-all-packages () (copy-list *list-all-packages*))
(defstruct (package (:constructor %make-package))
name
nicknames
use-list
used-by-list
shadowing-symbols
%obarray)
(defun* make-package (name &key nicknames uses size)
(assert (notany (function find-package) (cons name nicknames))
(name nicknames)
"There is already a package with the same name or nickname")
(let ((p (%make-package :name name
:nicknames nicknames
:use-list (or uses (find-package "EMACS-LISP"))
:%obarray (make-vector size nil))))
(push p *list-all-packages*)
(dolist (name (cons name nicknames))
(setf (gethash name *package-name-map*) p))
(internalize-used-symbols p)
p))
;; bootstrap the emacs-lisp package:
(defvar *package* (let ((p (%make-package :name "EMACS-LISP"
:nicknames '("ELISP")
:use-list '()
:%obarray obarray)))
(push p *list-all-packages*)
(dolist (name '("EMACS-LISP" "ELISP"))
(setf (gethash name *package-name-map*) p))
p))
(defmacro in-package (package-designator)
`(progn
(setf *package* (find-package ,package-designator))
(setf obarray (package-%obarray *package*))
*package*))
So, if you take care to always :use "EMACS-LISP" to always have access
to in-package, you can skip from one obarray to another for further
reading, because without modifying the reader, you cannot use
(elisp:in-package :elisp)
to come back.
You will need wrappers to map packages to obarray for function such
as intern.
Also, we could just use emacs-cl...
--
__Pascal Bourguignon__ http://www.informatimago.com/
next prev parent reply other threads:[~2010-06-03 9:26 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <143c6d28-4423-4e43-9fc5-c0fb3340043b@c11g2000vbe.googlegroups.com>
2010-05-31 15:44 ` About Emacs Modernisation Project Pascal J. Bourguignon
[not found] ` <0e994fe3-6dde-449f-879d-6701c7a195a9@e28g2000vbd.googlegroups.com>
2010-05-31 19:41 ` Alessandro Piras
[not found] ` <87iq63wsvt.fsf@kuiper.lan.informatimago.com>
2010-06-01 0:06 ` LanX
2010-06-01 8:44 ` Pascal J. Bourguignon
2010-06-01 11:19 ` LanX
2010-06-01 12:56 ` Pascal J. Bourguignon
2010-06-02 6:17 ` Xah Lee
[not found] ` <c41c63c0-b934-442d-8385-1abff6ab9b0b@s41g2000vba.googlegroups.com>
2010-06-01 0:40 ` Alessandro Piras
2010-06-02 6:07 ` Xah Lee
[not found] ` <87ljazofkn.fsf@rapttech.com.au>
2010-05-31 23:33 ` LanX
2010-06-01 10:28 ` Helmut Eller
2010-06-01 11:27 ` LanX
2010-06-01 12:29 ` Helmut Eller
2010-06-01 12:55 ` LanX
2010-06-01 12:59 ` Pascal J. Bourguignon
2010-06-01 12:59 ` Pascal J. Bourguignon
2010-06-02 17:05 ` Xah Lee
2010-06-02 17:50 ` Helmut Eller
[not found] ` <87r5krh3e0.fsf@unm.edu>
2010-06-01 8:40 ` Pascal J. Bourguignon
2010-06-01 17:34 ` rustom
2010-06-02 12:47 ` B. T. Raven
2010-06-02 17:20 ` rustom
2010-06-01 19:50 ` Stefan Monnier
2010-06-01 23:22 ` LanX
[not found] ` <slrni0b8nm.9k6.bergv@u00.math.uiuc.edu>
2010-06-02 11:39 ` Pascal J. Bourguignon
[not found] ` <e73e123d-3f0c-4a6f-bbac-b91fb71bf07d@f14g2000vbn.googlegroups.com>
2010-06-03 9:26 ` Pascal J. Bourguignon [this message]
2010-06-03 15:33 ` Emulating namespaces LanX
2010-06-03 17:41 ` Pascal J. Bourguignon
[not found] ` <87mxvegz12.fsf@unm.edu>
2010-06-01 23:36 ` About Emacs Modernisation Project Pascal J. Bourguignon
2010-06-02 5:58 ` Evans Winner
2010-06-04 18:33 ` Joseph Brenner
2010-06-05 2:55 ` Tim X
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