Re: Proper namespaces in Elisp

[Daniel Colascione <dancol@dancol.org>]

On May 8, 2020 5:13:00 PM Vladimir Sedach <vas@oneofus.la> wrote:

> Daniel Colascione <dancol@dancol.org> writes:
>> I wouldn't call package-local nicknames "throw[ing] away" the
>> namespace system. The post describes a logical extension. Is your
>> argument that the CL namespace system (suitably extended) *allows*
>> people to do silly things (like :use) even though it doesn't require
>> that they do?
>
> Yes, it is silly, and people do it. They will do it in Elisp if you
> let them. I think unintended re-definition of short names due to
> "namespace multiple inheritance" is going to be a problem for Elisp,
> because ordinary Emacs users load code from MELPA. It is a lot
> different than encountering the problem in C++ or something when you
> are a distribution maintainer compiling binaries. Neither the R6RS
> approach of throwing an error, nor clobbering the definition and
> showing a warning (what some Common Lisp implementations do) that
> will not be paid attention to is appropriate for what should be a
> backwards-compatible package update.


So there are three basic operations we can support: in Python syntax, 1) 
from PKG import * (exposing PKG.foo as foo), 2) import PKG as p (exposing 
PKG.foo as p.foo) and 3), from PKG import foo (exposing PKG.foo as foo).  
CL supports all three. I'm most interested in supporting #2, since that's 
closest to existing use. The lexspace prototype posted earlier today 
supports #3 and #1 (the latter via lexspace inheritance) only, but I think 
we should do #2 instead, and I think we can do it without runtime overhead.