Jarkko> This concept is handy when matching for diacritic-laden variants
Jarkko> of non-ASCII encodings. For example finding "bär" when matching
Jarkko> with "bar" would often be most convenient. The concept is not
Jarkko> limited for Western alphabets, it works also on
Jarkko> Cyrillic/Greek/Hebrew/Arabic/... alphabets.
We use a specific variation of this feature in our own Unicode regexp support
extensively for doing multilingual concordancing: we allow the users to ignore
non-spacing characters. This works for us because we generally work with
Unicode text in decomposed form.
In Perl, there is no luxury of assuming the text is always decomposed
properly, so equivalence classes could be constructed from the Unicode
Character Database as Jarkko points out.
Jarkko> Note, however, that to allow people defining their own equivalence
Jarkko> classes (somebody may want to add, change, or remove some class
Jarkko> definitions, if they don't match his particular tastes,
Jarkko> conventions, or languages.) This, of course, opens up the taint
Jarkko> gates...
User-level equivalence classes should perhaps be restricted to the familiar
"[xxxxxxx]." This keeps the messy details out of the syntax.
Jarkko> In addition to the POSIX 1003.2 notation,[=c=], I think we could
Jarkko> allow for a new regexp flag to turn the "ignore diacritics", just
Jarkko> like we have "ignore case". Maybe /d? (/e would have been be
Jarkko> nice but s///e preëmpted us.)
This would indeed be nice to have.
-----------------------------------------------------------------------------
Mark Leisher
Computing Research Lab The first virtue is to restrain the tongue;
New Mexico State University he approaches nearest to the gods who knows
Box 30001, Dept. 3CRL how to be silent, even though he is in the
Las Cruces, NM 88003 right. -- Cato the Younger (95-46 B.C.E)
