bug#27525: 25.1; Line wrapping of bidi paragraphs

[Itai Berli <itai.berli@gmail.com>]

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I appreciate your hard work. I can imagine that it took you a lot of time,
effort and agony to pull off this feature, and your efforts were
worthwhile: you created a good and helpful feature. For some purposes the
feature is perfect as it is, especially now that you've allowed
customization of the paragraph separator. I believe Emacs can be the #1
plain-text bidi editor out there, but this hinges on fixing this bug.

> I maintain that Emacs deviates from the UBA in a relatively minor way,
in an aspect that is only tangentially related to reordering
bidirectional text for display, and that raises its head in situations
that are relatively rare in practice, and in many of those rare cases
can be easily worked around by breaking long lines.

One of the valuable aspects of an ISO standard is that it is not left to
the personal judgment of a programmer to decide what is worth implementing,
and how to do so. It is not for you to decide what is a minor detail and
what is a major one, what is tangential and what is core. You need to
implement it to the letter, or else you can't claim conformance, no matter
how slight you imagine your deviation to be.

On what do you base your claim that this problem occurs relatively rarely
in practice? This is the kind of statement that only a specialist
linguist/statistician can make. And have you taken into account the type of
demographics who use Emacs' bidi feature and the kinds of texts they're
likely to type?

Contrary to what you said, my personal experience show that this is a major
inconvenience, and that it is a situation that occurs very often, almost
every paragraph, in fact, since I write primarily LaTeX documents where
English markup is intermixed with predominantly Hebrew text containing
frequent quotes from English textbooks and articles.

Yes, breaking lines is a possible workaround for LaTex, but it makes for
ugly and erratic looking paragraphs that are difficult to read and edit.
And what about documents that are not LaTeX? What workaround do they have?

You mention breaking "long lines", but this is not just a problem of long
lines. It takes just two English words inside a Hebrew paragraph that
happen to fall on a line break, to manifest this bug.

>  even today, 10 years later, still shines among all the
bidi-aware editors out there, certainly among those of the Free
Software variety.

Yes, Emacs shines as one of the very rare bidi-aware text editors that
enable entering explicit directional formatting characters. This is indeed
to Emacs' credit and is a very helpful feature.

However, Emacs also shines as possibly the only bidi-aware text editor that
botches the line wrapping of bidi paragraphs. Every single editor that I've
checked gets it right: from Word to Kate to GEdit to Google Docs to
BlueFish to TextEdit.

> And I don't really understand what is the purpose of your insistence
on the formal definition of this deviation.  It certainly won't help
fixing this issue any time soon, not unless someone steps forward to
do the job, which IMO is quite large.

I don't know what you mean by 'the formal definition of this deviation'. I
think that Emacs should not mislead the users and potential users. That it
should not claim to conform to a standard when it does not. I think that
when prospective users google "Emacs bidi" or "Emacs unicode" they will be
able to easily see that there's a problem with bidi line wrapping and that
if they require a text editor that is Unicode compliant they should look
elsewhere. The keywords are: transparency, truth in advertising,
user-friendly, and standards-oriented.

> The Emacs manual already describes this deviation.

In the online manual sections 22.19 (Bidirectional Editing) and 37.26
(Bidirectional Display) claim that Emacs implements the Unicode
Bidirectional Algorithm.


On Wed, Jul 19, 2017 at 8:28 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Itai Berli <itai.berli@gmail.com>
> > Date: Wed, 19 Jul 2017 15:59:14 +0300
> >
> > The Emacs manual and all official Emacs publications should make it
> clear that Emacs does not conform to
> > the Unicode Standard. Anything else is simply not true, and is a
> deliberate misleading.
>
> The Emacs manual already describes this deviation.
>

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