How to use string-to/as-unibyte correctly?

[Leo Liu]

Hi List,

As part of discussion on bug http://debbugs.gnu.org/23750, I am
wondering what is the deal with string-to/as-unibyte? How to use them
correctly or are they in their way out (obsolete)? Thanks.

,----[ Eli Zaretskii ]
| neither string-to-unibyte not string-as-unibyte should ever be used in
| applications, their use is more often than not a sign of some basic
| misunderstanding of text encoding.
`----

,----[ Eli Zaretskii ]
| Bottom line: like I said, there should be no reason to use
| string-*-unibyte in modern Emacs code on the url-http level or higher
| (maybe not at all). Its use is a sign of some basic misunderstanding,
| or a bug elsewhere, or remnant of old problems that no longer exist.
| So I think we should reconsider the solution on master as well.
`----

Leo