Re: Extracting information from PL_exception()

Hi Kaitain

you can find some very useful code from SWI-cpp.h, where text extraction is
modelled by means of type cast operators.

class PlException : public PlTerm {
...
  operator const char *(void);
  operator const wchar_t *(void);
}

near bottom of file, you can spot the actual definition

__inline PlException::operator const wchar_t *(void)
{ PlFrame fr;
...
}





2014-03-01 4:01 GMT+01:00 Kaitain Jones <[email protected]>:

> I'm trying to work out what information I'm able to extract from calling
> PL_exception() from C after a call to PL_next_solution() has failed. I've
> set up a test case in which the underlying PL predicate will hit a
> guaranteed error due to it referencing another predicate that has not in
> fact been defined. So PL_next_solution() fails, as expected, and
> PL_exception() succeeds and returns a term_t term value. But what exactly
> is the value so returned (or, rather, the structure to which it is a
> handle)? I've ascertained that it is of type PL_TERM. (This is using the
> latest SWI on Windows, btw.) But it isn't a list or a string, and the most
> info I've been able to extract is by calling PL_get_name_arity(...), which
> tells me that it has name "error" and is of arity 2. But...is that it?
>
> In my simple console app the corresponding call sends the exception to the
> console:
>
> ERROR: test_predicate/1: Undefined procedure: nonsense_predicate/1
> Exception: (6) nonsense_predicate(test_object) ?
>
> Trying to integrate into our full-blown windows app, I don't get this kind
> of error message for free. I was hoping that the exception might give it to
> me, but I can't tell from the documentation whether I should expect to have
> access to this message, and if so how to extract it. Any pointers would be
> appreciated.
>
> KJ
> -------------- next part --------------
> HTML attachment scrubbed and removed
> _______________________________________________
> SWI-Prolog mailing list
> [email protected]
> https://lists.iai.uni-bonn.de/mailman/listinfo.cgi/swi-prolog
>
-------------- next part --------------
HTML attachment scrubbed and removed