Re: EIEIO built in methods -- question

[Eric Abrahamsen]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> There's not a lot of documentation out there about using EIEIO, so I
> want to check something. First of all I'm using emacs-version "24.3.1"
> (the archlinux package).
>
> This is so everyday in Python (the other language I have experience in)
> and so weird to me in (e)lisp that I'm experiencing a kind of cognitive
> clash, and want to make sure I'm not doing something very wrong. How does
> this look to anyone who knows EIEIO (or I guess CLOS)?:
>
> (defclass persistent-thing (eieio-persistent)
>   ()
>   :documentation "Just for testing, :file slot comes from the superclass")
>
> (defmethod constructor :static ((thing persistent-thing) newname &rest slots)
>   (let ((filename (plist-get slots :file)))
>     (when (member filename my-big-bad-list-of-filenames)
>       (error "There's already a thing writing to %s" filename))
>    (apply 'call-next-method thing newname slots)))
>
> Is this how we should be doing it? Essentially, Python's "**kwargs"
> turns into "&rest slots" --> (apply 'call-next-method .... slots).
>
> I'd be interested in writing up a small introduction about how to use
> "internal" methods, ie methods on the eieio-default-superclass. So far
> I've messed with constructor, destructor, object-print, and I guess
> initialize-instance (oooh, damn, I just realized I should probably be
> using initialize-instance rather than constructor in my above example).

If you use initialize-instance rather than constructor, it looks like
`slots' comes wrapped in an extra list layer, meaning you need (plist-get
(car slots) :file).

Hence the need for documentation!