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Re: Proper namespaces in Elisp

From: João Távora
Subject: Re: Proper namespaces in Elisp
Date: Sat, 9 May 2020 20:11:05 +0100

On Sat, May 9, 2020 at 7:39 PM Daniel Colascione <address@hidden> wrote:
> On 5/9/20 11:35 AM, João Távora wrote:
> > On Sat, May 9, 2020 at 7:32 PM Daniel Colascione <address@hidden> wrote:
> >>
> >>
> >>
> >> On 5/9/20 11:23 AM, João Távora wrote:
> >>> On Sat, May 9, 2020 at 6:45 PM Daniel Colascione <address@hidden
> >>> <mailto:address@hidden>> wrote:
> >>>
> >>>
> >>>      Can you give a concrete example of a situation in which it'd be
> >>>      useful to
> >>>      do that? I think other people on the thread are right about
> >>>      discouraging
> >>>      bulk naked symbol imports.
> >>>
> >>>
> >>> For a submodule that you do control, it's not such a bad idea.
> >>
> >> Concrete example? If you want inheritance, you can get it with EIEIO.
> >
> > When writing a namespaced foo-tests.el library for your namespaced
> > foo.el library, for example.  Or for a big enough foo program, a 
> > foo-utils.el
> > that exports utils that only foo.el needs and noone else.
> Why not just re-enter the same namespace in your test file then?
> What problem are you actually trying to solve here?

In my foo-test.el file I have definitions, too. I don't want those definitions
to enter my foo namespace.  It's very simple to follow.

I don't know what you call module inheritance.   Look, you know the CL package
system right?  I'll just speak CL then, if you don't  mind:

;; foo-utils .lisp
(defpackage :foo-utils (:use :cl) (:export #:add-two))
(in-package :foo-utils)

(defun contorted-two-adder (x) (+ 1 1 x))
(defun add-two (x) (contorted-two-adder x))

;; foo.lisp
(defpackage :foo (:use :cl :foo-utils)  (:export #:bar))
(in-package :foo)

(defun bar () (add-two 40))

;; foo-tests.lisp
(defpackage :foo-tests (:use :cl :foo))
(in-package :foo-tests)

(defun check-forty-two-ness ()  (unless (eq (bar) 42)) (error "oh noes")))

Hope I didn't make many mistakes typing this in Gmail...

> package name prefix length, you can fix it with symbol rewriting without
> a ton of other complexity. I don't see a *need* for module inheritance

Again I don't know what you call "module inheritance". Maybe we're
just mis-communicating.  I'm just describing bog-standard "hide the
implementation" stuff.  I was suggesting reasonable uses of :USE, or
what I think you called "bulk symbol imports", i.e. merging two


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