In many applications it's wise to let Perl use Unicode for the strings it
processes. Most of the interfaces Perl has to the outside world are still
byte based. Programs therefore needs to decode byte strings that enter the
program from the outside and encode them again on the way out.

The POSIX locale system is used to specify both the language conventions
requested by the user and the preferred character set to consume and
output. The 'Encode::Locale' module looks up the charset and encoding
(called a CODESET in the locale jargon) and arrange for the Encode
module to know this encoding under the name "locale". It means
bytes obtained from the environment can be converted to Unicode strings by
calling 'Encode::encode(locale => $bytes)' and converted back again with
'Encode::decode(locale => $string)'.

Where file systems interfaces pass file names in and out of the program we
also need care. The trend is for operating systems to use a fixed file
encoding that doesn't actually depend on the locale; and this module
determines the most appropriate encoding for file names. The Encode
module will know this encoding under the name "locale_fs". For
traditional Unix systems this will be an alias to the same encoding as
"locale".

For programs running in a terminal window (called a "Console" on some
systems) the "locale" encoding is usually a good choice for what to expect
as input and output. Some systems allow us to query the encoding set for
the terminal and 'Encode::Locale' will do that if available and make these
encodings known under the 'Encode' aliases "console_in" and "console_out".
For systems where we can't determine the terminal encoding these will be
aliased as the same encoding as "locale". The advice is to use "console_in"
for input known to come from the terminal and "console_out" for output
known to go from the terminal.

In addition to arranging for various Encode aliases the following functions
and variables are provided:

* decode_argv( )

* decode_argv( Encode::FB_CROAK )

This will decode the command line arguments to perl (the '@ARGV' array)
in-place.

The function will by default replace characters that can't be decoded by
"\x{FFFD}", the Unicode replacement character.

Any argument provided is passed as CHECK to underlying Encode::decode()
call. Pass the value 'Encode::FB_CROAK' to have the decoding croak if not
all the command line arguments can be decoded. See the Encode/"Handling
Malformed Data" manpage for details on other options for CHECK.

* env( $uni_key )

* env( $uni_key => $uni_value )

Interface to get/set environment variables. Returns the current value as
a Unicode string. The $uni_key and $uni_value arguments are expected to
be Unicode strings as well. Passing 'undef' as $uni_value deletes the
environment variable named $uni_key.

The returned value will have the characters that can't be decoded
replaced by "\x{FFFD}", the Unicode replacement character.

There is no interface to request alternative CHECK behavior as for
decode_argv(). If you need that you need to call encode/decode yourself.
For example:

my $key = Encode::encode(locale => $uni_key, Encode::FB_CROAK);
my $uni_value = Encode::decode(locale => $ENV{$key}, Encode::FB_CROAK);

* reinit( )

* reinit( $encoding )

Reinitialize the encodings from the locale. You want to call this
function if you changed anything in the environment that might influence
the locale.

This function will croak if the determined encoding isn't recognized by
the Encode module.

With argument force $ENCODING_... variables to set to the given value.

* $ENCODING_LOCALE

The encoding name determined to be suitable for the current locale. The
Encode manpage knows this encoding as "locale".

* $ENCODING_LOCALE_FS

The encoding name determined to be suiteable for file system interfaces
involving file names. The Encode manpage knows this encoding as
"locale_fs".

* $ENCODING_CONSOLE_IN

* $ENCODING_CONSOLE_OUT

The encodings to be used for reading and writing output to the a console.
The Encode manpage knows these encodings as "console_in" and
"console_out".