Add :not_characters parameter to 'use locale'

This adds the parameter handling, tests, and documentation for this new
feature which allows locale and Unicode to play well with each other.

1 files changed, 47 insertions, 2 deletions

diff --git a/lib/locale.pm b/lib/locale.pm
index 2398599595..e57a5fded2 100644
--- a/lib/locale.pm
+++ b/lib/locale.pm
@@ -2,6 +2,8 @@ package locale;
 
 our $VERSION = '1.01';
 
+$Carp::Internal{ (__PACKAGE__) } = 1;
+
 =head1 NAME
 
 locale - Perl pragma to use or avoid POSIX locales for built-in operations
@@ -23,19 +25,62 @@ expressions, LC_COLLATE for string comparison, and LC_NUMERIC for number
 formatting).  Each "use locale" or "no locale"
 affects statements to the end of the enclosing BLOCK.
 
+Starting in Perl 5.16, a hybrid mode for this pragma is available,
+
+    use locale ':not_characters';
+
+which enables only the portions of locales that don't affect the character
+set (that is, all except LC_COLLATE and LC_CTYPE).  This is useful when mixing
+Unicode and locales, including UTF-8 locales.
+
+    use locale ':not_characters';
+    use open ":locale";           # Convert I/O to/from Unicode
+    use POSIX qw(locale_h);       # Import the LC_ALL constant
+    setlocale(LC_ALL, "");        # Required for the next statement
+                                  # to take effect
+    printf "%.2f\n", 12345.67'    # Locale-defined formatting
+    @x = sort @y;                 # Unicode-defined sorting order.
+                                  # (Note that you will get better
+                                  # results using Unicode::Collate.)
+
 See L<perllocale> for more detailed information on how Perl supports
 locales.
 
 =cut
 
+# A separate bit is used for each of the two forms of the pragma, as they are
+# mostly independent, and interact with each other and the unicode_strings
+# feature.  This allows for fast determination of which one(s) of the three
+# are to be used at any given point, and no code has to be written to deal
+# with coming in and out of scopes--it falls automatically out from the hint
+# handling
+
 $locale::hint_bits = 0x4;
+$locale::not_chars_hint_bits = 0x10;
 
 sub import {
-    $^H |= $locale::hint_bits;
+    shift;  # should be 'locale'; not checked
+    my $found_not_chars = 0;
+    while (defined (my $arg = shift)) {
+        if ($arg eq ":not_characters") {
+            $^H |= $locale::not_chars_hint_bits;
+
+            # This form of the pragma overrides the other
+            $^H &= ~$locale::hint_bits;
+            $found_not_chars = 1;
+        }
+        else {
+            require Carp;
+            Carp::croak("Unknown parameter '$arg' to 'use locale'");
+        }
+    }
+
+    # Use the plain form if not doing the :not_characters one.
+    $^H |= $locale::hint_bits unless $found_not_chars;
 }
 
 sub unimport {
-    $^H &= ~$locale::hint_bits;
+    $^H &= ~($locale::hint_bits|$locale::not_chars_hint_bits);
 }
 
 1;