Hi all, I have the following little script demonstrating a case (case 1 in the output below), which I can't explain to myself. So I hoped, someone can explain it to me or give the right hints. 
#!/usr/bin/perl -CO
use strict;
use warnings;
use Encode;

use utf8;


my $a = 'ä';
print "UTF8-Flag: ", utf8::is_utf8($a) ? "Yes" : "No";
print "    matches word: ", $a =~ /\w/ ? "Yes\n" : "No\n";

my $b = encode("ISO-8859-1", $a);
print "UTF8-Flag: ", utf8::is_utf8($b) ? "Yes" : "No";
print "    matches word: ", $b =~ /\w/ ? "Yes\n" : "No\n";

use locale;

$a = 'ä';
print "UTF8-Flag: ", utf8::is_utf8($a) ? "Yes" : "No";
print "    matches word: ", $a =~ /\w/ ? "Yes\n" : "No\n";

$b = encode("ISO-8859-1", $a);
print "UTF8-Flag: ", utf8::is_utf8($b) ? "Yes" : "No";
print "    matches word: ", $b =~ /\w/ ? "Yes" : "No";
print "\n";

[download]
The output on a linux box with locale de_DE.UTF-8 and perl source code encoded in UTF-8 is: 
UTF8-Flag: Yes    matches word: Yes
UTF8-Flag: No    matches word: No
UTF8-Flag: Yes    matches word: No
UTF8-Flag: No    matches word: No

[download]
It's the very first case I can't explain to me. Why is an unicode-flagged 'ä' matched against words when locale is not set explicitly?

Thanks in advance
Andreas

In reply to Regex Matching Unicode and Regex Classes by McA

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