Macro aborts even though regexp instance exists

Macro aborts even though regexp instance exists

[Swami Tota Ram Shankar]

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.

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.

Macro aborts even though regexp instance exists

[Swami Tota Ram Shankar]

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.

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.

Re: Macro aborts even though regexp instance exists

[Stefan Monnier]

> 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.
[...]
> to the original position when OR is entered and proceeds forward from
> there, but perhaps, the macro aborts.

Indeed, that's a problem: the macro aborts because macros abort not only
on error but also when `ding' is called.

> Any solutions?

You can work around the problem in this particular case as follows:
first do C-s M-r ONE\|TWO RET, and then record your macro using C-u C-s
C-s to recall the last regexp used, so it gets inserted "all at once"
without going through the problematic intermediate state (which is not
when it gets to \ but rather when it gets to ON or ONE and it doesn't
match anything).  Maybe isearch-search shouldn't call ding when the
match fails and we're matching regexps (and the match failed because of
a new char being added to search regexp, rather than because the user
hit C-s to jump to the next match).

Please M-x report-emacs-bug,


        Stefan

Re: Macro aborts even though regexp instance exists

[Stefan Monnier]

> 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.
[...]
> to the original position when OR is entered and proceeds forward from
> there, but perhaps, the macro aborts.

Indeed, that's a problem: the macro aborts because macros abort not only
on error but also when `ding' is called.

> Any solutions?

You can work around the problem in this particular case as follows:
first do C-s M-r ONE\|TWO RET, and then record your macro using C-u C-s
C-s to recall the last regexp used, so it gets inserted "all at once"
without going through the problematic intermediate state (which is not
when it gets to \ but rather when it gets to ON or ONE and it doesn't
match anything).  Maybe isearch-search shouldn't call ding when the
match fails and we're matching regexps (and the match failed because of
a new char being added to search regexp, rather than because the user
hit C-s to jump to the next match).

Please M-x report-emacs-bug,


        Stefan