[armedbear-devel] Design issue regarding condition printing (was: Error reporting problems)

[Erik Huelsmann]

Hi Alessio,

On Sat, Jan 22, 2011 at 11:12 AM, Alessio Stalla
<alessiostalla at gmail.com> wrote:
> On Sat, Jan 22, 2011 at 10:41 AM, Erik Huelsmann <ehuels at gmail.com> wrote:
>>> Anyway. Some comments, without having looked at the situation in detail:
>>> 1) disallowing overriding getMessage() feels wrong. The design may, and
>>> likely is, incomplete, but I got a very vague feeling that the function
>>> is serving a purpose. Now, I'm not entirely certain whether that purpose
>>> exists on the lisp or the java side. I don't have a clear picture of that
>>> yet.
>>
>> Right. I think I should have said "discourage overriding". However,
>> the original getMessage() should be reduced to "return null" - I
>> think, because it's calling writeToString() which itself is calling
>> getMessage() again...
>
> getMessage() is useful when an exception escapes to Java and you want
> to understand what happened (it's part of the API of Throwable and
> used to log the exception). Currently ABCL is not very helpful in that
> regard: if you disable the Lisp debugger to have exceptions propagated
> to Java (as it's often a case when you use ABCL as a library) you get
> back anonymous exceptions with no information on what happened. That
> is, I think, in important area of improvement.

Am I right to think that you'd do so by using
Interpreter._DEBUGGER_HOOK_FUNCTION_ ? If that's true, then you're
using Interpreter.UnhandledCondition to pass the error on to Java,
including its description.

Interpreter.UnhandledCondition uses <condition>.writeToString()
instead of using getConditionReport(). At least with my proposed
design, I'd advocate changing all calls to condition.writeToString()
to condition.getConditionReport() in those cases which are meant for
human readable output.

I'd say the above should solve your issue. It did make me realize that
it's not Primitives.ERROR which should bind the *PRINT-** variables,
but it should be getConditionReport() because it may be invoked in
multiple places.

Summarizing: I think getMessage() should be protected; it's a method
to change the behaviour of getConditionReport(). The latter should be
public, because *that*'s the method which should be used all over the
place.

Agreed?

Bye,


Erik.