Re: bidi-display-reordering is now non-nil by default

[David Kastrup]

Eli Zaretskii <address@hidden> writes:

>> From: David Kastrup <address@hidden>
>> Date: Sun, 31 Jul 2011 11:15:24 +0200
>> 
>> I was not suggesting detecting them.  I was suggesting that modes
>> creating buffers where paragraphs are not a usable concept disable
>> paragraph detection.  Manually.
>
> Setting bidi-paragraph-direction to a non-nil value has precisely the
> same effect, except that it will also DTRT when the mode wants all its
> paragraphs have right-to-left direction.  Disabling detection of
> paragraph direction can only support left-to-right, by contrast (or
> some other static default).
>
>> That's another bottomless pit
>
> We could do this through the modes (buffer-menu.el already does), but
> my concern was about modes that are not bundled with Emacs, such as
> mew, which was what triggered this thread in the first place.

How about setting bidi-paragraph-direction to nil only in text-mode,
giving it a non-nil default otherwise?

That would seem to have a much better hit/miss ratio as specializing on
buffer names.

>> but at least it approaches the problem from an angle that is not
>> bidi-related and might make sense on versions (including XEmacs) that
>> don't bother about bidi at all and consequently don't support
>> bidi-paragraph-direction.
>
> bidi-paragraph-direction is a variable.  Setting a variable cannot
> hurt, even if the version of Emacs one runs doesn't know about it.  Am
> I missing something?

The willingness of maintainers to add code for features that are
irrelevant to the functionality of their package and their Emacs
version?

"My mode does not have bidi, so why should I tell Emacs it has a bidi
direction when it makes no user-visible difference except avoiding a
performance bug" is harder to convincingly counter than "My mode does
not have paragraphs, so why should I tell Emacs it does not have
paragraphs when it makes a user-visible difference with the paragraph
movement commands".

-- 
David Kastrup