Re: ignore-error?

[Lars Ingebrigtsen <larsi@gnus.org>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> It seems like people like writing `ignore-errors' a lot more than
>> `condition-case', and I think `ignore-errors' is the wrong thing to say
>> 90% of the time.
>
> I agree, but I think in 99% of those cases, the author has no idea which
> error might need to be caught.

That's true.  If only Emacs Lisp had...  checked exceptions.  *runs
away*

*then returns*

But it sure would be nice if we had some way of telling at least some of
the errors that a function can raise... 

>> So would it be a good idea to add a new convenience macro `ignore-error'
>> to entice people to not use `ignore-errors' so much?  It would take an
>> error condition as its parameter, so:
>>
>>   (ignore-error 'file-error
>>     (directory-files dir))
>
> [ I think the argument shouldn't be quoted.  ]

True.

> More importantly, if you want me to use this, you'll have to improve
> elisp-mode's completion so it DTRT for the error symbol, like it does in
> condition-case.

Let's see...  It this stuff?

                       ((and (or 'condition-case 'condition-case-unless-debug)
                             (guard (save-excursion
                                      (ignore-errors
                                        (forward-sexp 2)
                                        (< (point) beg)))))
                        (list t obarray
                              :predicate (lambda (sym) (get sym 'error-conditions))))

Sure, that should be simple enough to cargo cult for the new macro, I
think.

The parameter should perhaps also be allowed to be a list of symbols:

(ignore-error (file-error some-other-error)
  (foo))

?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no