"LS" == Laurent Siebenmann writes:

 >> but you can add definitions like
 >> \def\setcyr{\fontencoding{T2A}\selectfont}
 >> \def\setlat{\fontencoding{T1}\selectfont}

 LS> That leaves us switching between two environments rather than the
 LS> expected three.

 LS> Having done this sort of programming, I would guess that all
 LS> switching could be eliminated via a more complex UTF8 macro
 LS> package.

i had some ideas on improving the utf-8 input encoding package which
will provide "transparent" font encoding switching on demand.
i think i know a fairly good method for this, but i didn't have time
to implement it yet.

But - if we think about this more, it will become obvious that a
multilingual document must have language switching macros at least for
good hyphenation.

E.g., the text should look like

some text in default language (e.g. english)
\switchtorussian
some text in russian (using utf-8 input encoding)
\switchtopolish
some text in polish (using utf-8 input encoding)
\switchtogerman
some text in german (using utf-8 input encoding)
\switchtoenglish
  ...

where \switchto<language> commands can also look in babel style, e.g.
\begin{otherlanguage}{russian}
  some text in russian (using utf-8 input encoding)
\end{otherlanguage}

The necessity of switching LANGUAGE in the markup of the document (not
input encoding which may be UTF-8 and contain ALL letters of all
needed languages, and not font encoding which may be implemented in a
smarter utf-8 package) is necessary because obviously there is no
other way TeX can grok the language: only the author of text knows
that.

And without these language-switching markup commands, hyphenation will
be wrong.

Note, that even Omega still needs these markup language-switching
commands, by the same reasons!

So, we do agree that markup commands like \switchtorussian,
\switchtogerman, etc are necessary - for good hyphenation.

But then, what prevents us to include automatic font encoding
switching inside them?

And we can see that it is not that bad to have not so smart utf-8.def
which requires font encoding switching commands, -- these commands can
be put inside language switching commands which ARE REQUIRED for
quality typesetting -- be it TeX or Omega.

Best,
v.