How do I use String methods on UTF-8 characters?

Question

How do I use String methods on UTF-8 characters?

For example, I have a string with Cyrillic characters, so when I use string.upcase it doesn't work.

Answer 1

Ruby only supports case conversions on the letters A–Z and a–z.

The reason for this is simply that case conversions for other letters aren't well defined. For example, in Turkish 'I'.downcase # => 'ı' and 'i'.upcase # => 'İ', but in French 'I'.downcase # => 'i' and 'i'.upcase # => 'I'. Ruby would have to know not only the character encoding, but also the language to do that correctly.

Even worse, in German

'MASSE'.downcase

is either

'maße'   # "measurements"
'masse'  # "mass"

In other words: you need to actually understand the text, i.e. you need a full-blown AI, to do case conversions correctly.

And I myself have actually accidentally constructed a sentence once, which was undecidable even for a human.

In short: it's simply impossible to do correctly, which is why Ruby doesn't do it at all. There are third-party libraries, however, like the Unicode library and ActiveSupport, which do support a somewhat larger subset of characters.