utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
use utf8; no utf8;
use utf8 pragma tells the Perl parser to allow UTF-8 in the
program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
no utf8 pragma tells Perl to switch back to treating
the source text as literal bytes in the current lexical scope.
This pragma is primarily a compatibility device. Perl versions earlier than 5.6 allowed arbitrary bytes in source code, whereas in future we would like to standardize on the UTF-8 encoding for source text. Until UTF-8 becomes the default format for source text, this pragma should be used to recognize UTF-8 in the source. When UTF-8 becomes the standard source format, this pragma will effectively become a no-op. For convenience in what follows the term UTF-X is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
utf8 pragma has the following effect:
Bytes in the source text that have their high-bit set will be treated as being part of a literal UTF-8 character. This includes most literals such as identifier names, string constants, and constant regular expression patterns.
On EBCDIC platforms characters in the Latin 1 character set are treated as being part of a literal UTF-EBCDIC character.
Note that if you have bytes with the eighth bit on in your script
(for example embedded Latin-1 in your string literals),
will be unhappy since the bytes are most probably not well-formed
UTF-8. If you want to have such bytes and use utf8, you can disable
utf8 until the end the block (or file, if at top level) by
The following functions are defined in the
utf8:: package by the perl core.
lc()work as expected on strings containing characters in the range 0x80-0xFF. Note that this should not be used to convert a legacy byte encoding to Unicode: use Encode for that. Affected by the encoding pragma.
utf8::encode is like
utf8::upgrade, but the UTF8 flag is
cleared. See perlunicode for more on the UTF8 flag and the C API
sv_utf8_decode, which are wrapped by the Perl functions
utf8::decode. Note that in the Perl 5.8.0 implementation the
functions utf8::valid, utf8::encode, utf8::decode, utf8::upgrade,
and utf8::downgrade are always available, without a
statement-- this may change in future releases.
One can have Unicode in identifier names, but not in package/class or subroutine names. While some limited functionality towards this does exist as of Perl 5.8.0, that is more accidental than designed; use of Unicode for the said purposes is unsupported.
One reason of this unfinishedness is its (currently) inherent unportability: since both package names and subroutine names may need to be mapped to file and directory names, the Unicode capability of the filesystem becomes important-- and there unfortunately aren't portable answers.