From: Yukihiro Matsumoto <matz@...>
Date: 2011-01-23T07:59:57+09:00
Subject: [ruby-core:34799] Re: [Ruby 1.9-Bug#4298] Duration of calling String#[] with the same index is strangely related to string length.

Hi,

In message "Re: [ruby-core:34793] [Ruby 1.9-Bug#4298] Duration of calling String#[] with the same index is strangely related to string length."
    on Sun, 23 Jan 2011 03:42:20 +0900, Charles Nutter <redmine@ruby-lang.org> writes:

|Perhaps I'm mistaken, but isn't RSTRING_LEN the byte length of the string? Isn't that always guaranteed to be >= str_strlen, which is the character length? And doesn't this patch basically break completely if beg is greater than the encoded character length but not greater than the raw byte length?

RSTRING_LEN is the byte length of the string, but we can assume
RSTRING_LEN > str_strlen(str,enc), I think.

|I believe this is one reason Python 3+ allows you to force all strings to be either UTF-8 or UTF-32 in-memory, and only supports those two encodings. It is also one of the original reasons Java and .NET chose to use UTF-16, though that obviously became a small problem when Unicode expanded to 24 bits...

Unfortunately, UTF-16 is no longer fixed length encoding since
introduction of surrogate pairs.  Almost same for UTF-32 with IVS.

							matz.