Re: active strings in luatex?

[Arthur Reutenauer <arthur.reutenauer@normalesup.org>]

> XeTeX always converts, say, c + combining caron into a ccaron whenever
> one exists in the font

  Does it really?  I had understood from the last discussion on the
XeTeX list that it did not, with the example of capital alpha +
combining breathing which was not set correctly.  But maybe it's LaTeX's
fault?

>                                    In the case of LM, the font has
> combining characters with zero width with the accent shifted to the
> left, so that it looks OK on an average glyph

  That's a nice trick, but in the case of 'l', it looks really ugly.

>                                               (but in general, TeX
> does a better job with combining characters) unless one requests two
> accents.

  Sure.

> So, either ccaron or c+combining caron (or l+combining tilde) should
> behave the same way:

  Yes, of course.  This is Unicode canonical equivalence, explained in
the links Idris gave in the Unicode Standard (chapter 2 is "Introduction",
chapter 3 is "Conformance", and we may be concerned by chapter
"Implementation guidelines", too).

> Also, {\v x} and other strange combinations don't work in ConTeXt (I
> guess it does in plain TeX) since ConTeXt MK II uses a clever way to
> figure out if such characters exist in the font encoding

  Mapping sequences like "\v c" to the appropriate slot in the current
font encoding is quite legitimate; LaTeX does the same with its own font
encodings.  I didn't know it meant things like "\v x" couldn't be
displayed, though.  That said, it is something different from supporting
combining characters.

	Arthur
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