bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Richard Stallman]

1. Char-fold isearch is a screw.  I wanted to search for lines
starting with a space, so I searched for C-j SPC, but it did something
useless.  It found every blank line!

2. So I decided to try to disable it, but the doc string of
isearch says nothing about how to turn that off.  It should say how.

3. I tried using C-h v to find a variable, but although there is
isearch-case-fold-search, there is no isearch-char-fold-search.
For parallelism's sake, isearch-char-fold-search should exist.

4. I searched in etc/NEWS for 'char fold' and 'char-fold'.
Neither appears.  Both of them SHOULD appear, for the sake
of people who search for them.

5. I did find 'isearch', and that entry described the new inconvenient
feature.  However the entry there did not say how to disable this
feature.  It should say how.




In GNU Emacs 25.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.24.23)
 of 2015-08-12 on freetop
Repository revision: 79a169684dfad2c0bbb9fdbae539c1f30d9f0ac3
System Description:	Trisquel GNU/Linux 7.0, Belenos

Configured using:
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Major mode: Help

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[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]


-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Andreas Schwab]

Richard Stallman <rms@gnu.org> writes:

> 1. Char-fold isearch is a screw.  I wanted to search for lines
> starting with a space, so I searched for C-j SPC, but it did something
> useless.  It found every blank line!

That has nothing to do with char-fold, this feature already exists since
24.3 and is called lax-whitespace.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Mark Oteiza]

Richard Stallman <rms@gnu.org> writes:

> 2. So I decided to try to disable it, but the doc string of
> isearch says nothing about how to turn that off.  It should say how.
>
> 3. I tried using C-h v to find a variable, but although there is
> isearch-case-fold-search, there is no isearch-char-fold-search.
> For parallelism's sake, isearch-char-fold-search should exist.
>
> 4. I searched in etc/NEWS for 'char fold' and 'char-fold'.
> Neither appears.  Both of them SHOULD appear, for the sake
> of people who search for them.
>
> 5. I did find 'isearch', and that entry described the new inconvenient
> feature.  However the entry there did not say how to disable this
> feature.  It should say how.

As I understand it, the variables `character-fold-search' and
`replace-character-fold' control the new folding features. I have it all
disabled--both variables set to nil. At least they have docstrings;
however, yes, they need to be documented in isearch, replace, and NEWS.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > That has nothing to do with char-fold, this feature already exists since
  > 24.3 and is called lax-whitespace.

How come it did not occur in the Emacs I was running before last week?
I built that from master a few months ago.

Anyway, it is a total screw.  Who likes this as a default?

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > That has nothing to do with char-fold, this feature already exists since
  > 24.3 and is called lax-whitespace.

If char-fold really only affects ASCII and Unicode lookalikes, is it
important enough to be worth mentioning in the echo area?  If not,
let's delete it from the echo area.

Does anyone really want to disable it?

On the other hand, lax whitespace search by default is a drastic
change.  That should be listed in the echo area, and its default
should be nil.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Tassilo Horn]

Richard Stallman <rms@gnu.org> writes:

>   > That has nothing to do with char-fold, this feature already exists since
>   > 24.3 and is called lax-whitespace.
>
> How come it did not occur in the Emacs I was running before last week?
> I built that from master a few months ago.
>
> Anyway, it is a total screw.  Who likes this as a default?

I like that behavior because I frequently search for "some text" in
prose, and then it allows me to find also the matches where the two
words are wrapped around.

But I think the `isearch-lax-whitespace' feature can still be improved:

1. The `isearch-lax-whitespace' docstring speaks of "ordinary
   incremental search" which I've read as "non-regex isearch".  But it
   seems that regex isearch is also affected.  I'd just strip the
   "ordinary".

2. More importantly, isearching for C-j SPC matches any sequence of two
   whitespace characters, e.g., it matches between here  and  here, too.
                                                       ^^   ^^
I had expected that only space characters in the search string are
replaced by `search-whitespace-regexp' but it seems that any whitespace
character is replaced by it.  I think this is not good.

And IMHO, it would be a good idea to disable lax-whitespace for the
current search as soon as the search string contains a non-space
whitespace character.  I think if the user explicitly types C-j, C-i,
etc. she's probably not interested in treating spaces as any-whitespace
but wants to distinguish newlines from tabs and spaces.

Bye,
Tassilo

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Drew Adams]

FYI: This is the thread that discussed this feature, in quite a lot
of detail (behavior, defaults, toggling, chars to match, indication
in echo area or elsewhere, etc.).

http://lists.gnu.org/archive/html/emacs-devel/2012-08/msg00502.html

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Artur Malabarba]

2015-08-18 13:30 GMT+01:00 Tassilo Horn <tsdh@gnu.org>:
> I like that behavior because I frequently search for "some text" in
> prose, and then it allows me to find also the matches where the two
> words are wrapped around.

Me too, it's very useful in prose. I agree that it's not super useful
in code. But it's also not harmful enough in code that it should be
disabled in prose.

> But I think the `isearch-lax-whitespace' feature can still be improved:
> [...]
> I had expected that only space characters in the search string are
> replaced by `search-whitespace-regexp' but it seems that any whitespace
> character is replaced by it.  I think this is not good.

I agree.

> And IMHO, it would be a good idea to disable lax-whitespace for the
> current search as soon as the search string contains a non-space
> whitespace character.  I think if the user explicitly types C-j, C-i,
> etc. she's probably not interested in treating spaces as any-whitespace
> but wants to distinguish newlines from tabs and spaces.

I'm so sure this would be good, but I'm not sure it would be bad either.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Artur Malabarba]

>> but wants to distinguish newlines from tabs and spaces.
>
> I'm so sure this would be good, but I'm not sure it would be bad either.

I'm NOT so sure...

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Artur Malabarba]

> 2. So I decided to try to disable it, but the doc string of
> isearch says nothing about how to turn that off.  It should say how.
>
> 3. I tried using C-h v to find a variable, but although there is
> isearch-case-fold-search, there is no isearch-char-fold-search.
> For parallelism's sake, isearch-char-fold-search should exist.
>
> 4. I searched in etc/NEWS for 'char fold' and 'char-fold'.
> Neither appears.  Both of them SHOULD appear, for the sake
> of people who search for them.
>
> 5. I did find 'isearch', and that entry described the new inconvenient
> feature.  However the entry there did not say how to disable this
> feature.  It should say how.

All good points. I'll try to address all of these when I can.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > Me too, it's very useful in prose. I agree that it's not super useful
  > in code. But it's also not harmful enough in code that it should be
  > disabled in prose.

It was in prose that it screwed me!  I wanted to search for NL SPC,
but it found NL NL instead.

See another message in this batch
for an idea for making this work better.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Juri Linkov]

> 3. I tried using C-h v to find a variable, but although there is
> isearch-case-fold-search, there is no isearch-char-fold-search.
> For parallelism's sake, isearch-char-fold-search should exist.

There are both case-fold-search and its isearch-specific counterpart
isearch-case-fold-search, so maybe both char-fold-search and
isearch-char-fold-search should exist.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Juri Linkov]

> If char-fold really only affects ASCII and Unicode lookalikes, is it
> important enough to be worth mentioning in the echo area?  If not,
> let's delete it from the echo area.

One idea was to not display default parameters in the echo area.
So when e.g. char-fold search is t by default then it should not
be indicated in the echo area.

> Does anyone really want to disable it?

Like case-fold search, char-fold search could be disabled either by
customizing the corresponding variable, or interactively with ‘M-s '’.

> On the other hand, lax whitespace search by default is a drastic
> change.  That should be listed in the echo area, and its default
> should be nil.

AFAIK, a drastic change was not in lax whitespace search per se, but
only in its combination with char-fold search that we could fix now.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Juri Linkov]

> But I think the `isearch-lax-whitespace' feature can still be improved:
>
> 1. The `isearch-lax-whitespace' docstring speaks of "ordinary
>    incremental search" which I've read as "non-regex isearch".  But it
>    seems that regex isearch is also affected.  I'd just strip the
>    "ordinary".

Regexp isearch is affected by ‘isearch-regexp-lax-whitespace’.

> And IMHO, it would be a good idea to disable lax-whitespace for the
> current search as soon as the search string contains a non-space
> whitespace character.  I think if the user explicitly types C-j, C-i,
> etc. she's probably not interested in treating spaces as any-whitespace
> but wants to distinguish newlines from tabs and spaces.

Good idea - it could work the same way as case-fold search detects the presence
of uppercase chars in the search string to automatically toggle itself.

bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Artur Malabarba]

[-- Attachment #1: Type: text/plain, Size: 415 bytes --]

> There are both case-fold-search and its isearch-specific counterpart
> isearch-case-fold-search, so maybe both char-fold-search and
> isearch-char-fold-search should exist.

Actually, `isearch-case-fold-search' is an internal variable and
configuring it has no effect. If you want configure isearch's case-folding,
you have to use the general `case-fold-search'.

That is why there's no isearch-char-fold-search.

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bug#21277: 25.0.50; char-fold search is a screw, and I can't see how to disable

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > > If char-fold really only affects ASCII and Unicode lookalikes, is it
  > > important enough to be worth mentioning in the echo area?  If not,
  > > let's delete it from the echo area.

  > One idea was to not display default parameters in the echo area.
  > So when e.g. char-fold search is t by default then it should not
  > be indicated in the echo area.

Might be good.

  > > Does anyone really want to disable it?

  > Like case-fold search, char-fold search could be disabled either by
  > customizing the corresponding variable, or interactively with ‘M-s '’.

Yes, but does anyone really ever want to disable it?

  > > On the other hand, lax whitespace search by default is a drastic
  > > change.  That should be listed in the echo area, and its default
  > > should be nil.

  > AFAIK, a drastic change was not in lax whitespace search per se, but
  > only in its combination with char-fold search that we could fix now.

Is that a certainty?  I now think the problem is simply in lax
whitespace search.  Some evidence is that it occurs in an Emacs from a
year ago, in which char-fold search did not exist.


-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.