[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Message Passing with GOOPS

From: Michael Tiedtke
Subject: Re: Message Passing with GOOPS
Date: Fri, 26 Jun 2015 12:15:07 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0

On 26/06/2015 10:18, Ralf Mattes wrote:
This is a first "raw" definition where the parameter /message/ has to be a
quoted symbol.

(define-method (call (receiver <object>) message . arguments)
   (apply (slot-ref receiver message) arguments))

The class definition still looks like traditional GOOPS but it works.

An example:

(define-class <receiver> ()
   (msg #:init-value (lambda () 'hello-world)))

(define r (make <receiver>))
(call r 'msg) => 'hello-world

Now I'd like to have an easier syntax for describing the slot. The
definition might be:

(define-syntax define-message
   (syntax-rules ()
     ((_ (message-name arguments ... ) body ...)
      (message-name #:init-value (lambda (arguments ...) body ...)))))

But the following example doesn't work in 1.8:

(define-class <house> ()
   (define-message (phone n)
     (repeat n (lambda () (bell) 'rang)) ))

GOOPS complains about malformed slots and *seems* to see the unexpanded

  $ guile-1.8
  guile> (use-modules (oop goops))
  guile> define-class
  #<macro! define-class>

Why would you expect a macro to evaluate its arguments? :-)
The use of macros within macros is yet to be evaluated. But as syntax transformers sometimes check their arguments before these expressions are expanded if they are macros - one should really think about Scheme's macro expansion model.

Do you think syntax transformers have in any way anything to do with the evaluation of code?

I could use a little help here, anyone?* Even for the naming scheme: /send/
is already used by unix sockets and methods are part of the implementation
of generics. Perhaps /message/ isn't that bad.
That's what modules are for.

guile> (define-module (ios) #:export (send))  ; ios = Inferior Object System

and then:

guile> (ios:send ....)

Yes, just call it r-0b-delta-36x7 and let people rename it to find out what it means.

Perhaps it's better to recreate a clean object model without 3,000 lines of
C code like GOOPS. But then GOOPS really creates the illusion of an object
oriented environment with a MOP ...
Why, 3000 lines of C code seems like a rather lean codebase for an objet system.

Seems like your sentence is not a valid expression in Scheme.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]