From: Tanaka Akira <akr@...>
Date: 2010-05-10T12:42:13+09:00
Subject: Re: wcswidth, ruby 1.9, and string encodings

2010/5/10 William Morgan <wmorgan-ruby-talk@masanjin.net>:
>
> I need some advice about how to use wcswidth on Ruby 1.9 strings.
> Wcswidth returns the column width of a string, i.e. how much of the
> horizontal space on the screen a string takes up when printed to a
> terminal. Being able to calculate column width is crucial for any
> console-based program that deals with non-ASCII characters. For example,
> Chinese characters typically take up two columns.

I wrote such code in my terminfo binding.
http://github.com/akr/ruby-terminfo

> Unfortunately, this code requires that the string's encoding match your
> LC_CTYPE, because mbstowcs relies on LC_CTYPE to produce wchar_t's. If
> those don't match, you'll either get nothing, or, possibly, a wrong
> answer.

I used rb_locale_encoding() to convert to LC_CTYPE as follows:

  str = rb_str_encode(str, rb_enc_from_encoding(rb_locale_encoding()), 0, Qnil);
-- 
Tanaka Akira