I believe, that part of the confusion lays in the badly written modules. Since perl provides function "is_utf8", it is very easy to check what kind of input the user has provided and use appropriate "Encode::encode" or "Encode::decode" to get the desired form.

You seem to equate "is a text string" with "is_utf8 returns true". That's wrong.

Perl has two possible internal formats: Latin-1 and UTF-8. It is perfectly fine for decoded text string to be stored in Latin-1. Decoding it again just because is_utf8 returns false is just wrong.

Example (on a UTF-8 terminal; note that -CS sets the :encoding(UTF-8) layer on STDOUT, among other things): 

$ perl -CS -Mstrict -wE 'say "\x{ab}oo\x{bb}"'
«oo»
$ perl -CS -Mstrict -wE 'say utf8::is_utf8 "\x{ab}oo\x{bb}"'

$ # let's convince ourselves that lc() works properly:
$ perl -CS -Mstrict -wE 'say "\x{C6}"'
Æ
$ perl -CS -Mstrict -wE 'say lc "\x{C6}"'
æ
$ perl -CS -Mstrict -wE 'say utf8::is_utf8 "\x{C6}"'

$

[download]

Summary: Strings internally stored as Latin 1 can be perfectly fine text strings. Trying to use is_utf8 to determine whether a string holds characters or octects is wrong.

In fact, every string can be seen as a text string (which functions like lc and uc do), though if you forgot to decode the input data, the user will be surprised by the result.

Perl 6 - second systems done right

In reply to Re^3: text encodings and perl by moritz
in thread text encodings and perl by andal

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.