Using non-ASCII characters in packages

Question

What is the best way to use non-ASCII (say, Cyrillic) characters in a .sty file?

If it's used in a LaTeX file that uses \inputenc[utf8]{inputenc}, than one can just use utf8 encoding in the .sty file and everything's fine. Or the other way round: one can add \RequirePackage[utf8]{inputenc} to the .sty file. But in any case, the author of .tex file has to use the encoding used in .sty file.

Is there a way to specify encoding in the .sty file, so it may be used in a .tex file in any encoding?

(Recipe that is also compatible with XeLaTeX would be especially nice.)

Answer 1

Edited (my original answer was quite confusing): The babel package has this problem, because it needs to translate "Table of contents", and so on into other languages, in a way that doesn't force a particular encoding on the document author. The way babel deals with Cyrillic (which can be used in with multiple input encodings) without forcing an a choice, is to use encoding-dependent commands (\cyrr, \cyre, etc).

Answer 2

It's generally not a good idea to use non-ascii characters in LaTeX packages, since TeX doesn't have much understanding of input encodings, but inputenc itself provides a command to specify the encoding:

\inputencoding{encoding name}

It may perform what you need, but the better idea would be to use standard LaTeX control sequences for such characters. (Of course, this isn't always convenient, hence your question.)

For XeLaTeX packages, it's a different story, because XeTeX can handle different input encodings natively. For this, you can use the \XeTeXinputencoding primitive.