Re: Line/column numbers in user supplied exception handlers

[Marius Vollmer]

Neil Jerram <address@hidden> writes:

>     Marius> I would deprecate catch/throw.
> 
> OK, now you've outflanked me!  Could you explain the big picture?

Uh, oh, I'd rather not since I don't have a very clear big picture
myself.  I like the Common Lisp condition system quite a bit, better
than the withdrawn error handling SRFI, which in turn I like better
than the existing Guile system.

The thing about catch/throw in particular is that I think it is abused
for error handling.  It conflates two concepts that should be kept
separate: non-local transfers of control, and registering for handling
certain exceptional situations.

For the `non-local transfer of control part', we should use call/cc or
a more efficient variant like `call/ec' (with or without
`escape-protect').

For the `registering for handling exceptions', we should use a new
mechanism like `call-with-exception-handler' that runs the handlers in
the dynamic context of the exception.

There are quite some details, like whether we should have only a
single current exception handler, or a list of them, that I'm not sure
about yet.