Re: Anomalous results from is-a? and instance? on current-input-port

[Alan Grover]

It's confusing to have an "object" with class, superclasses, etc., but 
not be "an instance". Since "class-of" returns a value (the Goops 
class), that implies it is a Goops instance.

What would be the predicate for determining that something is an 
instance of a class, capable of the introspection procedures, works with 
specialization by inheritance, but not a Goops object?

Mikael Djurfeldt wrote:
> On Tue, 15 Feb 2005 18:39:44 -0500, Alan Grover <address@hidden> wrote:
>
> > Guile 1.6.4
> > Linux xxxx 2.6.5-7.145-default #1 Thu Jan 27 09:19:29 UTC 2005 i686 i686
> > i386 GNU/Linux
> > SuSe 9.1
> >
> > Some instance and class introspection procedures give anomalous results.
> > Specifically, they seem to give false when they shouldn't.
> >
> > My results (from code below, just for current-input-port). Note the #f's":
> > ; from interactive guile
> > (class #<<class> <soft-input-port> 8087280>
> >  instance? #f
> >  (is-a? <soft-input-port>) #f
> >  class-direct-supers (#<<class> <soft-port> 80872b0> #<<class>
> > <input-port> 8084110>)
> >  (is-a? <input-port>) #t
> >
> > Results are repeatable if tried in the same interactive interpreter, or
> > run from a script. However, I get the following variations:
> >
> > * Run from a script: (is-a? <soft-input-port>) #t
> > * Use my .guile: (is-a? <soft-input-port>) #t
>
>
> * instance? should give #f since the port is not a normal GOOPS
> instance but rather a built-in datatype.
>
> * the class-direct-supers list looks OK
>
> * (is-a? <input-port>) gives the correct value #t
>
> The only thing anomalous above is that (is-a? x <soft-input-port>)
> gives #f in the interpreter.
> I can't repeat that in the development version, so it seems specific
> to Guile-1.6.4. Can someone else look into that?
>
> Thanks,
> M

--
Alan Grover
address@hidden
+1.734.476.0969