Re: How to describe something in Lisp?

[Johan Andersson <johan.rejeep@gmail.com>]

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Thanks all for your answers.

All of your examples will work fine in my case. But is it "accepted" by
Emacs users to code a mode using these structures? I've never seen them
before.

On Tue, Feb 3, 2009 at 5:40 PM, Pascal J. Bourguignon <pjb@informatimago.com
> wrote:

> Andreas Politz <politza@fh-trier.de> writes:
>
> > Johan Andersson wrote:
> >> Hi!
> >> As a Java and Ruby programmer I sometimes find it hard to code
> >> Lisp. Right
> >> now I'm working on a minor mode for which the structure would obvious
> for me
> >> in Java or Ruby, but in Lisp is a riddle.
> >> I will not describe the mode itself, but give a description of the
> >> problem.
> >> Say I want to store a list of people in a file. And for each person,
> also
> >> some information on them in the format:
> >> name|age|married|sex
> >> Each time I start the mode, that file should be parsed in to some
> >> datastructure (which kind of is the problem). And on save, the file
> would be
> >> updated. For me it's obvious to represent a person with a class:
> >> [...]
> >>  I read something about object orientation in lisp, but I have never
> >> seen this be used in Emacs. So my question is basically: What is the
> best
> >> way to model something in lisp, that you in an object oriented language
> >> would model with a class.
> >> Thanks!
> >
> > (defstruct person
> > [...]
>
> There is also EIEIO which is an implementation of CLOS, the Common
> Lisp Object System, adapted for emacs.
>
> You can find it part of http://cedet.sourceforge.net/
>
> Then you can define your objects:
>
> (require 'eieio)
>
> (defclass person
>  ((name       :type string :initarg :name      :accessor name)
>   (birthdate  :type date   :initarg :birthdate :accessor birthdate))
>   (status     :type marital-status :initarg  :martial-status :accessor
> martial-status)
>   (sex        :type (member :male :female) :initarg :sex :accessor sex))
>
> (defmethod age ((p person))
>  (date- (now) (birthdate p)))
>
> ...
>
> --
> __Pascal Bourguignon__
>

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