[DGD] New DGD user introducing himself...

[Erwin Harte]

On Fri, Aug 31, 2001 at 08:34:02PM +0200, Troels Therkelsen wrote:
> Hey all,
> 
> I apologise in advance if this e-mail is long and rambling, and if it
> appears twice on this list... I had forgotten which address I signed up
> with ;-)
> 
[...]
> 
> With all the strict typing going around, and the addition of LWOs, I have to
> say I'm curious why you can't type objects ala Java, eg.,
> 
>   void func(object /lib/lwo/sorter obj);
> 
> Then func() would only accept objects either inheriting /lib/lwo/sorter or
> being that object themselves.  Without this object typing, basically all
> your objects are 'mixed'.  Especially with LWOs and passing them between
> functions, it would be very convenient to have the runtime system do the
> type checking for you.

Easy to do yourself (which is a common theme in DGD):

* Put a nomask function in /lib/lwo/sorter.c with a known name, for
  instance like this:

  nomask void   __lib_lwo_sorter() {}

* Do a check for function_object(the-function-name, obj) to see if it
  is indeed the one in /lib/lwo/sorter like this

  object obj_fo;

  obj_fo = function_object("__lib_lwo_sorter", obj);
  if (!obj_fo || !object_name(obj_fo) != "/lib/lwo/sorter") {
      error("Bad argument 1 to function func");
  }

Of course you can wrap this stuff in some macros to make life easier.

> Maybe too Java-ish for LPC, I dunno.  This certainly is a Java-ism:
> 
>   FACTORY:
>   object sorter() {
>     object ret = new_object {
>       int compare(int a, int b) {
>         return ((a == b) ? 0 : ((a > b) ? -1 : 1));
>       }
>     }
> 
>     return ret;
>   }
> 
>   A:
>   int *arr = ({ ... });
> 
>   arr = sort_array(arr, FACTORY->sorter());

And how is this different from having some utility functions in a
library object that you inherit and then use?

Quite possibly I missed the point of the example, though. *grin*

Welcome aboard and you can leave the ranting to me, you can do the
rambling if you want. ;-)

Erwin.
-- 
Erwin Harte <harte at xs4all.nl>
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