Re: autoaloading facility

[Greg Badros <gjb AT cs.washington dot edu>]

Mikael Djurfeldt <mdj@mdj-pc.nada.kth.se> writes:

> Klaus Schilling <Klaus.Schilling@home.ivm.de> writes:
> 
> > Emacs lisp has an autoloading facility which enables to load the full
> > definition of a function at the time it is needed first time. Could
> > something like that also be provided in guile? or do lexical scoping
> > and monolithic namespace prevent that?
> 
> There actually exists such a facility in 1.3.2.  You do:
> 
> (define-module (my-module)
>   :autoload (some auto loaded module) (foo bar baz))
> 
> Any time when foo, bar or baz are referenced, (some auto loaded module)
> will be loaded.

Is there special support for autoloads in the root module?  Autoloads
are most important for a user's .scwmrc.  Also, it's more useful to have 
the autoloading be specified anywhere, not just in a define-module
header.  Bernard's technique seems generally useful -- it'd be nice if
its functionality were included in guile.

This gives me an idea.  I asked a week or so ago if there was a better
way to conditionally use a module instead of having to repeat all of the 
use-modules.  The below is the simplest (and least-painful) example of
how we currently do things:

;; guile-version variable is nice to have; perhaps guile should provide it
;; (define-public guile-version (+ (string->number (major-version)) 
;;				(/ (string->number (minor-version)) 10)))
(if (> guile-version 1.3)
    (define-module (app scwm path-cache)
      :use-module (ice-9 popen)
      :use-module (ice-9 string-fun))
    (define-module (app scwm path-cache)
      :use-module (ice-9 string-fun)))

Ideally, this would be:

(define-module (app scwm path-cache)
   :use-module (ice-9 string-fun)
   :use-module-if (ice-9 popen) (> guile-version 1.3))

But it seems as though:

(define-module (app scwm path-cache)
   :use-module (ice-9 string-fun)
   :autoload (ice-9 popen) (use-ice-9-popen))

(if (> guile-version 1.3) use-ice-9-popen)

might be a way to get a similar behaviour now.  (Though the
use-module-if keyword makes a lot of sense, IMO.)

Thanks,
Greg