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Re: [Scheme-reports] Exception handling
Vincent Manis scripsit:
> It is somewhat less useful than I had at first thought, I realized
> earlier today that most built-in functions would create a subtype of
> ERROR-OBJECT, and that ERROR in particular would do so. I'd therefore
> like to suggest loosening the language a bit, though I don't have
> immediate new wording to suggest.
Not necessarily; the objects returned by R6RS ERROR belong to sibling
types of the various implementation-signaled errors. Note that R7RS WG1
does not have a notion of subtypes at all.
> > I'm really opposed to that: simple programs ought to be able to
> > throw simple objects, especially when the conditions don't represent
> > exceptions.
> Since every WG1 program is (supposed to be) a WG2 program, that means
> that it's perfectly acceptable for a WG2 module to offer a procedure
> that does a RAISE 4, and and for another WG2 module that also, for
> very different reasons to do the same. This would make using these two
> modules together extremely difficult, which sort of defeats the idea
> of programming-in-the-large.
Yes, but that's a matter of self-discipline in module writing. If
you make the effect of (raise 4) implementation-dependent, there is
no guarantee that it will be caught by the exception subsystem at
all. Perhaps you meant that some object is raised, but which object is
I suggest you solicit aid of my followers John Cowan
or learn the difficult art of mud-breathing. cowan@x
--Great-Souled Sam http://www.ccil.org/~cowan
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