Re: Macro aborts even though regexp instance exists - Serious Bug

[Kevin Rodgers]

On 10/22/12 2:40 PM, Swami Tota Ram Shankar wrote:
> Hi emacs users,
>
> I write a simple macro which works, however, it fails in a particular
> case.
>
> C-s
> M-r
>
> to get into isearch-forward-regexp
>
> and give a regexp like
>
> ONE\|TWO
>
> It works for every TWO and ONE as long as there is a ONE ahead of TWO.
> In the last instance, no ONE exists after TWO and it fails.
>
> \|<=>  OR or disjunction.
>
> Any solutions?
>
> This is such a fundamental issue that I think its a bug. When the C-s
> M-r  is used outside the macro definition, the cursor gladly returns
> to the original position when OR is entered and proceeds forward from
> there, but perhaps, the macro aborts.

It is not a bug: when ONE fails to match the buffer, C-s (which is designed
for interactive use, obviously) signals an error, which terminates the macro
execution.

That's because there is no way for C-s to know that you _might_ type \|TWO
after ONE.

So the solution is to make sure that the regexp is not complete after ONE:
C-s \(ONE\|TWO\)

> I guess, this can lead to a lot of confusion and time wastage, if the
> user is unaware of this and most likely to neglect it because its
> contrary to normal usage.

Yes, there is a lot of confusion and wasted time when a user is not aware
of how to use a program.

> I include more newsgroups because of the seriousness of this bug.

Whatever :-)

--
Kevin Rodgers
Denver, Colorado, USA