On 2017-01-29, Georg Baum wrote: > Guenter Milde wrote: >> ... There may be issues with documents containing literal Unicode >> dashes: these may now have different line breaks.
> If this is an issue then it was already an issue when format 481 was > introduced (because we changed -- to U+2013 and --- to U+2014 in the > conversion). Unfortunatly, yes. It turns out the correct change would have been to change -- to U+2013,U+200B and --- to U+2014,U+200B (or to SpecialChars). Why? * --- is converted to EM DASH by TeX via font ligature. * TeX insert a line breaking opportunity (LBO) after each HYPHEN (-) and suppresses hyphenation in the preceding word, also if three HYPHENs become an EM DASH by ligating. * TeX does *not* insert an LBO afte a literal EM DASH or \textemdash macro while the Unicode standard recommends LBOs before and after EM DASH. Exception: XeTeX treats literal dashes and \textemdash macro like the ligatures - no hypenation in the word before, LBO after. This behaviour can be switched of by the preamble command * Unicode and LyX/LaTeX recommend/support the Zero Width Space U+200B (ZWSP) as representation of a line break opportunity that does not insert a hyphen (in contrast to the SOFT HYPHEN). As a result, the TeX input string "---" is functionally equivalent to EM DASH + ZWSP (except for missing hyphenation of the preceding word with "---"). For more "research", background and links, see http://www.lyx.org/trac/ticket/10543 > If native support for both versions of dashes (-- vs. \textendash in LaTeX) > is really needed then this should be done via a special char inset. The SpecialChar inset(s) could either be a) insets for "ligature dashes" -- and --- +1 full backwards compatibility with fileformat <481 b) inset for zero width space ZWSP +2 versatile: currently there is no LyX support for a line breaking opportunity that does not insert a hyphen (except for a literal ZWSP that is invisible in the GUI) +1 can be implemented as space inset instance +0 backwards compatible with fileformat <481 when replacing --- by EM DASH + SpecialChar(ZWSP) (Except for not suppressing hyphenation in the preceding word, but it may be argued that this is actually an improvement) >> It is not about "horrible look", but about WYSIWYM: >> Treat hyphens similar to other TeX ligatures (e.g. << and >>) and special >> characters: >> * show on screen what you will get in the output >> * escape in LaTeX export. >> If the LyX GUI shows "get the LyX version with `lyx --version`", I don't >> want a suprise `lyx –version` in the output. > This is the most important point IMO (and the very reason to introduce > format 481 which fixed https://www.lyx.org/trac/ticket/3647). Yes. > I have no strong opinion about the UI for entering en-dashes and em-dashes. > If there are better methods than the current one then the UI should change. I favour an LFUN for input. This can be bound to the - key by default. It could be extended to allow an optional argument "allowbreak" that would add (and care for) ZWSP after the DASHES. Günter
