Re: [emacs-bidi] Bidirectional editing in Emacs -- main design decisions

[mhsekhavat]

Hi,


Eli Zaretskii wrote
>  If Emacs would follow UAX#9 to the letter, each line could have different
> base direction,
>    which is, of course, intolerable.  We could avoid this nonsense by
>    using the "soft newline" or similar features, but I firmly believe
>    that Emacs should DTRT with bidirectional text even in the simplest
>    modes, including the Fundamental mode, where every newline is hard.
> 
>    Fortunately, UAX#9 acknowledges that applications could have other
>    ideas about what is a "paragraph".  It calls this ``higher
>    protocol''.  So I decided to use such a higher protocol -- namely,
>    the Emacs definition of a paragraph, as determined by the
>    `paragraph-start' and `paragraph-separate' regexps.  Therefore, the
>    first strong directional character after `paragraph-start' or
>    `paragraph-separate' determines the paragraph direction, and that
>    direction is kept for all the lines of the paragraph, until another
>    `paragraph-separate' is found.  (Of course, this means that
>    inserting a single character near the beginning of a paragraph
>    might affect the display of all the lines in that paragraph, so
>    some of the current redisplay optimizations which deal with changes
>    to a single line need to be disabled in this case.)

I agree that most of the time, having different base direction for each line
is nonsense. But there are cases where the text does not have "paragraph"s,
but consists of a number of sentences, each in a line. So an empty line does
not semantically mean paragraph separator and a right-to-left line appears
just after a left-to-right line.

How can I set variables `paragraph-start` and `paragraph-separate` so that
each line have different direction? I tried setting `paragraph-start` to "."
and `paragraph-separate` to "$" but didn't work?

Thanks for the great work on bidi.



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