Re: Why do Glib::ustring::operator[] and at() return values, not references?

[Chris Vine <vine35792468 gmail com>]

On Sat, 24 Jun 2017 15:51:49 +0100
Daniel Boles <dboles src gmail com> wrote:
> Title says it all really. I had to use an std::string in one place
> because I needed to modify it quickly and with less hassle than
> using .replace() - and Glib::ustring won't let me get a reference to
> perform such modification.
>
> The documentation states
>     "No reference return; use replace()
> <https://developer.gnome.org/glibmm/stable/classGlib_1_1ustring.html#a0f0c9b5aaad58279d3ac87a86a173f4a>
> to write characters."
> but does not explain why, nor does the commit log: these comments were
> added way back in the initial revision.
>
> So I'm wondering whether there's really a reason for this, or if it
> is just something that no one has wanted to change (until now!)

It is because UTF-8 is a multibyte encoding, and any one character may
require between 1 and 5 bytes to represent it.  If you were allowed to
change a byte at will you would be able to introduce invalid encoding
sequences.  As to the absense of documentation, maybe it is because this
was thought to be self-evident, dunno.