Re: elisp's cl package. Don't understand the notice about eval-when-compile

[Kevin Rodgers]

Xah Lee wrote:
> in emacs lisp's CL package documentation “(info "(cl)Overview")”, it
> has this passage:
>
>    *Please note:* the "CL" functions are not standard parts of the
> Emacs Lisp name space, so it is legitimate for users to define them
> with other, conflicting meanings.  To avoid conflicting with those
> user
> activities, we have a policy that packages installed in Emacs must not
> load "CL" at run time.  (It is ok for them to load "CL" at compile
> time
> only, with `eval-when-compile', and use the macros it provides.)  If
> you are writing packages that you plan to distribute and invite
> widespread use for, you might want to observe the same rule.
>
> I don't quite understand it.
>
> If i distribute a package xyz.el, which calls
>
> (eval-when-compile (require 'cl))
>
> And, this package does not require users to byte-compile it. Then,
> how's the eval-when-compile solve the name conflict problem?
>
> does it imply that if you distribute a package using cl, it must be
> byte compiled eventually?

Of course, no library _must_ be compiled.  But the unstated assumption
is that every library is byte-compiled because of the performance
benefits (during loading _and_ execution).

And if you load and execute a compiled library that uses CL macros (but
not CL functions) via eval-when-compile, then the obarray remains pure.
:-)

--
Kevin Rodgers
Denver, Colorado, USA