[gambit-list] How to handle and access and interact with object members host code

Dimitris Vyzovitis vyzo at hackzen.org
Sun Dec 13 06:44:49 EST 2015


to be more precise:

gambit's reader allows you to specify a symbolic macro for curly braces {}
we use @method, so when the reader sees {print o "hello"} it gets read
to (@method print o hello).
@method is a (user-programmable) core macro, with default expansion to
(call-method 'print o "hello")

call-method in gambit is implemented like this:
(define (call-method obj id . args)
  (cond
   ((method-ref obj id)
    => (lambda (method) (apply method obj args)))
   (else
    (error "Cannot find method" obj id))))

(define (method-ref obj id)
  (and (object? obj)
       (find-method (object-type obj) id)))

hope that helps,
-- vyzo

On Sun, Dec 13, 2015 at 12:39 PM, Dimitris Vyzovitis <vyzo at hackzen.org> wrote:
> Or you can do what we use in gerbil:
> {print o "hello"}
>
> reader translates to (call-method 'print o "hello")
>
> -- vyzo
>
> On Mon, Dec 7, 2015 at 5:13 PM, Marc Feeley <feeley at iro.umontreal.ca> wrote:
>> At the Scheme level, you can express the OO style in various ways.  Here are 2 that come to mind:
>>
>> 1) Your “new” operator could return a closure which receives as a first parameter the name of the method to be called.  So you could:
>>
>> (define o (new Lib))
>> (o print: "hello")
>>
>> or
>>
>> (define .print '.print)
>> (o .print "hello")
>>
>> 2) You could make .print a function that receives as a first parameter the object on which the method applies.  For example:
>>
>> (define .print (lambda (self text) …))
>> (define o (new Lib))
>> (.print o "hello")
>>
>> You can of course use macros to automate these styles.
>>
>> Marc
>>
>>> On Dec 7, 2015, at 8:31 AM, ben yakawp <ben.lists at yakawp.com> wrote:
>>>
>>> hi
>>> Sorry if this too obvious, but I don't understand how gambit handles
>>> objects from the hosts backend.
>>>
>>>
>>> For example: if one would like to construct a 'Node' library for the JS
>>> backend, how would you do that? The whole node api seems to be object
>>> oriented.  But also the Python standard libaries (batteries) are layed
>>> out class based. You had to do something like
>>>
>>> (define o (new Lib))
>>> (o.print "hello")
>>>
>>> This looks wrong. What am I missing?
>>>
>>> Regards
>>> ben
>>> _______________________________________________
>>> Gambit-list mailing list
>>> Gambit-list at iro.umontreal.ca
>>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list
>>
>> _______________________________________________
>> Gambit-list mailing list
>> Gambit-list at iro.umontreal.ca
>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list


More information about the Gambit-list mailing list