Re: foreign predicate not working (one more observation)

[Paulo Moura]

On 19/jul/2004, at 15:25, Saurabh Bhatla wrote:

> :- foreign(get_event_ob(+string,-string)).
>
> :-object(receiver).
>
>         :-public(receive/1).
>         :-public(validate/1).
>         :-public(get_event_ob/2).
>         
>         receive(Event).
>
>         validate(Event):-
>                 self(Self),
>                 Self::get_event_ob(Event,Object),
>                 write(Object),  
>                 write('<-object found for event->'),
>                 write(Event),nl.
>
>         validate(Event):-
>                 write('No object found for event->'),
>                 write(Event),nl.
>                 
>
> :-end_object.

Note that, because get_event_ob/2 is _declared_ as a _public predicate_ 
inside the object receiver, calls such as the following one:

>                 Self::get_event_ob(Event,Object),

always fail without error as get_event_ob/2 is within the scope of 
Self. Being a static predicate with no clauses, means that the calls to 
it always fail (you could be declaring a predicate which would only be 
defined in descendant objects).

Cheers,

Paulo


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Paulo Jorge Lopes de Moura
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