Re: [Scheme-reports] Exception handling Vincent Manis (01 May 2011 06:25 UTC)
Re: [Scheme-reports] Exception handling John Cowan (01 May 2011 09:49 UTC)
Re: [Scheme-reports] Exception handling Andy Wingo (01 May 2011 12:39 UTC)

Re: [Scheme-reports] Exception handling John Cowan 01 May 2011 09:49 UTC

Vincent Manis scripsit:

> No, I don't think so. I would like WG1 to consider (raise 4) illegal,
> as well as (raise x) for any value of x not produced by some variation
> of MAKE-ERROR-OBJECT. Then WG2 can decide to allow additional
> kinds of objects to be raised, without breaking compatibility with
> WG1. In my naïvete, I felt that making the action for (raise 4) be
> implementation-dependent would do this, but I'm happy with any other
> strategy that leads to the same result.

In my view that is too restrictive.  Allowing any object means that
WG1 users can roll their own condition types using DEFINE-RECORD-TYPE,
exporting the appropriate predicate and accessors from their modules,
without any bureaucratic restrictions.  Alternatively, they can use
association lists or the like.  This would not be possible if only
error objects were allowed: everything would have to be fitted into the
straitjacket of message + irritants.

--
La mayyitan ma qadirun yatabaqqa sarmadi                            John Cowan
Fa idha yaji' al-shudhdhadh fa-l-maut qad yantahi.              cowan@ccil.org
                --Abdullah al-Hazred, Al-`Azif      http://www.ccil.org/~cowan

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