[XeTeX] Bug or design flaw in Polyglossia 2012/04/29 v1.2.1

[Arthur Reutenauer]

On Sat, Mar 30, 2013 at 08:49:57PM +0100, Peter Dyballa wrote:
> When the missing characters are obviously Latin, why aren't they
> taken from a Latin script, from \englishfont for example?

  Because nobody has ever implemented this, nor even come up with a
specification for how Polyglossia should behave.  In this case you've
set up two languages, Malayalam and English.  What if you're having a
third language, say, German: where should TeX choose the Latin
characters from, English or German?

  I'm really surprised that you expect Polyglossia to switch fonts
automatically, because it has never been the case, and if we wanted to
implement that now -- which can certainly be very useful in some cases
-- I would be wary of breaking many existing documents.  Because of the
way things work now, users may precisely expect the font not to change
automatically.

  On a minor point, Polyglossia's language switching mechanisms -- as
they are devised now -- don't rely on font settings by language, but
rather by script: hence \englishfont in your example above is completely
useless, and \latinfont would make more sense (which partly addresses my
comment in the first paragraph, actually; but again, someone has to
write support for that ...)

	Arthur