perldelta: re-order "Core Enhancements" entries

[perl5.git] / lib / strict.pm

diff --git a/lib/strict.pm b/lib/strict.pm
index d1479ed..923c921 100644 (file)
--- a/lib/strict.pm
+++ b/lib/strict.pm
@@ -1,19 +1,54 @@
 package strict;
 
-$strict::VERSION = "1.02";
+$strict::VERSION = "1.11";
+
+my ( %bitmask, %explicit_bitmask );
+
+BEGIN {
+    # Verify that we're called correctly so that strictures will work.
+    # Can't use Carp, since Carp uses us!
+    # see also warnings.pm.
+    die sprintf "Incorrect use of pragma '%s' at %s line %d.\n", __PACKAGE__, +(caller)[1,2]
+        if __FILE__ !~ ( '(?x) \b     '.__PACKAGE__.'  \.pmc? \z' )
+        && __FILE__ =~ ( '(?x) \b (?i:'.__PACKAGE__.') \.pmc? \z' );
+
+    %bitmask = (
+        refs => 0x00000002,
+        subs => 0x00000200,
+        vars => 0x00000400,
+    );
+
+    %explicit_bitmask = (
+        refs => 0x00000020,
+        subs => 0x00000040,
+        vars => 0x00000080,
+    );
 
-my %bitmask = (
-refs => 0x00000002,
-subs => 0x00000200,
-vars => 0x00000400
-);
+    my $bits = 0;
+    $bits |= $_ for values %bitmask;
+
+    my $inline_all_bits = $bits;
+    *all_bits = sub () { $inline_all_bits };
+
+    $bits = 0;
+    $bits |= $_ for values %explicit_bitmask;
+
+    my $inline_all_explicit_bits = $bits;
+    *all_explicit_bits = sub () { $inline_all_explicit_bits };
+}
 
 sub bits {
     my $bits = 0;
     my @wrong;
     foreach my $s (@_) {
-       push @wrong, $s unless exists $bitmask{$s};
-        $bits |= $bitmask{$s} || 0;
+        if (exists $bitmask{$s}) {
+            $^H |= $explicit_bitmask{$s};
+
+            $bits |= $bitmask{$s};
+        }
+        else {
+            push @wrong, $s;
+        }
     }
     if (@wrong) {
         require Carp;
@@ -24,12 +59,19 @@ sub bits {
 
 sub import {
     shift;
-    $^H |= bits(@_ ? @_ : qw(refs subs vars));
+    $^H |= @_ ? &bits : all_bits | all_explicit_bits;
 }
 
 sub unimport {
     shift;
-    $^H &= ~ bits(@_ ? @_ : qw(refs subs vars));
+
+    if (@_) {
+        $^H &= ~&bits;
+    }
+    else {
+        $^H &= ~all_bits;
+        $^H |= all_explicit_bits;
+    }
 }
 
 1;
@@ -52,6 +94,10 @@ strict - Perl pragma to restrict unsafe constructs
 
 =head1 DESCRIPTION
 
+The C<strict> pragma disables certain Perl expressions that could behave
+unexpectedly or are difficult to debug, turning them into errors. The
+effect of this pragma is limited to the current file or scope block.
+
 If no import list is supplied, all possible restrictions are assumed.
 (This is the safest mode to operate in, but is sometimes too strict for
 casual programming.)  Currently, there are three possible things to be
@@ -82,17 +128,17 @@ is allowed so that C<goto &$AUTOLOAD> would not break under stricture.
 
 =item C<strict vars>
 
-This generates a compile-time error if you access a variable that wasn't
-declared via "our" or C<use vars>,
-localized via C<my()>, or wasn't fully qualified.  Because this is to avoid
-variable suicide problems and subtle dynamic scoping issues, a merely
-local() variable isn't good enough.  See L<perlfunc/my> and
-L<perlfunc/local>.
+This generates a compile-time error if you access a variable that was
+neither explicitly declared (using any of C<my>, C<our>, C<state>, or C<use
+vars>) nor fully qualified.  (Because this is to avoid variable suicide
+problems and subtle dynamic scoping issues, a merely C<local> variable isn't
+good enough.)  See L<perlfunc/my>, L<perlfunc/our>, L<perlfunc/state>,
+L<perlfunc/local>, and L<vars>.
 
     use strict 'vars';
     $X::foo = 1;        # ok, fully qualified
     my $foo = 10;       # ok, my() var
-    local $foo = 9;     # blows up
+    local $baz = 9;     # blows up, $baz not declared before
 
     package Cinna;
     our $bar;                  # Declares $bar in current package
@@ -108,18 +154,31 @@ exempted from this check.
 
 This disables the poetry optimization, generating a compile-time error if
 you try to use a bareword identifier that's not a subroutine, unless it
-appears in curly braces or on the left hand side of the "=E<gt>" symbol.
-
+is a simple identifier (no colons) and that it appears in curly braces or
+on the left hand side of the C<< => >> symbol.
 
     use strict 'subs';
-    $SIG{PIPE} = Plumber;      # blows up
-    $SIG{PIPE} = "Plumber";    # just fine: bareword in curlies always ok
-    $SIG{PIPE} = \&Plumber;    # preferred form
-
-
+    $SIG{PIPE} = Plumber;   # blows up
+    $SIG{PIPE} = "Plumber"; # fine: quoted string is always ok
+    $SIG{PIPE} = \&Plumber; # preferred form
 
 =back
 
 See L<perlmodlib/Pragmatic Modules>.
 
+=head1 HISTORY
+
+C<strict 'subs'>, with Perl 5.6.1, erroneously permitted to use an unquoted
+compound identifier (e.g. C<Foo::Bar>) as a hash key (before C<< => >> or
+inside curlies), but without forcing it always to a literal string.
+
+Starting with Perl 5.8.1 strict is strict about its restrictions:
+if unknown restrictions are used, the strict pragma will abort with
+
+    Unknown 'strict' tag(s) '...'
+
+As of version 1.04 (Perl 5.10), strict verifies that it is used as
+"strict" to avoid the dreaded Strict trap on case insensitive file
+systems.
+
 =cut