[XeTeX] Conflict between xunicode and fontspec?

[Arthur Reutenauer]

> Do you mean that I would have to write "Ah bon?" *only* when I use XeLaTeX?
> And "Ah bon ?" (with 0x00A0) for my mails, news articles, Word documents,
> scripts, etc.

  U+00A0 NO-BREAK SPACE is not the kind of space required by French
typographic rules before question marks, exclamation marks and
semicolons.  The appropriate character is closer to U+202F NARROW
NO-BREAK SPACE (“espace fine insécable” in French typography), and this
is the one you should type if you want to convey that precise meaning.
If you type U+00A0, which is a normal no-break space (“espace mot
insécable”), you should not expect it to behave magically as a narrower
no-break space – unless, of course, you rely on a more elaborate text
processor which you *know* will handle those characters according to
different rules (a “higher-level protocal”, as Unicode puts it).  But
such an expectation would, generally speaking, not be Unicode-compliant.

  Incidentally, U+00A0 NO-BREAK SPACE does also occurr in French
typography, since it is the amount of space required by most
typographers before the colon (not the other punctuation marks); some,
though, would put a narrow no-break space here, and it's of course up to
you to choose what space you want to put, so the difference really makes
sense, I think (and is endorsed by Babel-French, where the colon is
indeed preceded by a full no-break space, whereas the other special
punctuation marks have a narrow no-break space before them).

  To sum up, wanting to be smart and inputting the appropriate Unicode
characters directly is of course legitimate, and should be handled
correctly by XeLaTeX (this is the “first step” I highlighted in my
previous post); but if you only go half the way, I don't consider it
should be a priority for Polyglossia to correct your input – although I
do think this would be a nice thing to do, but there would be a number
of problems involved, and it could take time to do so (especially
because one would not like to implement the same solution as Babel by
making punctuation marks active).  On the other hand, if you don't want
to bother about the exact character to key in before the “double”
punctuation marks, Polyglossia-French requires you (for the moment) to
type no space at all, for technical reasons – and I expect this would be
more convenient to the vast majority of French-speaking users, who
wouldn't know how to input a no-break space in the first place.

	Arthur

P-S for Adam: Maybe you understand now what I meant when I wrote that
“many TeX users do things which are not Unicode-compliant in a much
worse way” last week-end.  I could not ask for a better example :-)