[shell changes from patch from perl5.003_26 to perl5.003_27]

[p5sagit/p5-mst-13.2.git] / lib / strict.pm

diff --git a/lib/strict.pm b/lib/strict.pm
index adaf47c..8492e93 100644 (file)
--- a/lib/strict.pm
+++ b/lib/strict.pm
@@ -1,11 +1,84 @@
 package strict;
 
+=head1 NAME
+
+strict - Perl pragma to restrict unsafe constructs
+
+=head1 SYNOPSIS
+
+    use strict;
+
+    use strict "vars";
+    use strict "refs";
+    use strict "subs";
+
+    use strict;
+    no strict "vars";
+
+=head1 DESCRIPTION
+
+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
+strict about:  "subs", "vars", and "refs".
+
+=over 6
+
+=item C<strict refs>
+
+This generates a runtime error if you 
+use symbolic references (see L<perlref>).
+
+    use strict 'refs';
+    $ref = \$foo;
+    print $$ref;       # ok
+    $ref = "foo";
+    print $$ref;       # runtime error; normally ok
+
+=item C<strict vars>
+
+This generates a compile-time error if you access a variable that wasn't
+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>.
+
+    use strict 'vars';
+    $X::foo = 1;        # ok, fully qualified
+    my $foo = 10;       # ok, my() var
+    local $foo = 9;     # blows up
+
+The local() generated a compile-time error because you just touched a global
+name without fully qualifying it.
+
+=item C<strict subs>
+
+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.
+
+
+    use strict 'subs';
+    $SIG{PIPE} = Plumber;      # blows up
+    $SIG{PIPE} = "Plumber";    # just fine: bareword in curlies always ok
+    $SIG{PIPE} = \&Plumber;    # preferred form
+
+
+
+=back
+
+See L<perlmod/Pragmatic Modules>.
+
+
+=cut
+
 sub bits {
     my $bits = 0;
+    my $sememe;
     foreach $sememe (@_) {
-       $bits |= 0x00000002 if $sememe eq 'refs';
-       $bits |= 0x00000200 if $sememe eq 'subs';
-       $bits |= 0x00000400 if $sememe eq 'vars';
+       $bits |= 0x00000002, next if $sememe eq 'refs';
+       $bits |= 0x00000200, next if $sememe eq 'subs';
+       $bits |= 0x00000400, next if $sememe eq 'vars';
     }
     $bits;
 }