Version bump to go along with change #27185

[perl5.git] / lib / strict.pm

diff --git a/lib/strict.pm b/lib/strict.pm
index adaf47c..d14391a 100644 (file)
--- a/lib/strict.pm
+++ b/lib/strict.pm
@@ -1,23 +1,136 @@
 package strict;
 
+$strict::VERSION = "1.03";
+
+my %bitmask = (
+refs => 0x00000002,
+subs => 0x00000200,
+vars => 0x00000400
+);
+
 sub bits {
     my $bits = 0;
-    foreach $sememe (@_) {
-       $bits |= 0x00000002 if $sememe eq 'refs';
-       $bits |= 0x00000200 if $sememe eq 'subs';
-       $bits |= 0x00000400 if $sememe eq 'vars';
+    my @wrong;
+    foreach my $s (@_) {
+       push @wrong, $s unless exists $bitmask{$s};
+        $bits |= $bitmask{$s} || 0;
+    }
+    if (@wrong) {
+        require Carp;
+        Carp::croak("Unknown 'strict' tag(s) '@wrong'");
     }
     $bits;
 }
 
+my $default_bits = bits(qw(refs subs vars));
+
 sub import {
     shift;
-    $^H |= bits(@_ ? @_ : qw(refs subs vars));
+    $^H |= @_ ? bits(@_) : $default_bits;
 }
 
 sub unimport {
     shift;
-    $^H &= ~ bits(@_ ? @_ : qw(refs subs vars));
+    $^H &= ~ (@_ ? bits(@_) : $default_bits);
 }
 
 1;
+__END__
+
+=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
+    $file = "STDOUT";
+    print $file "Hi!"; # error; note: no comma after $file
+
+There is one exception to this rule:
+
+    $bar = \&{'foo'};
+    &$bar;
+
+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 C<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>.
+
+    use strict 'vars';
+    $X::foo = 1;        # ok, fully qualified
+    my $foo = 10;       # ok, my() var
+    local $foo = 9;     # blows up
+
+    package Cinna;
+    our $bar;                  # Declares $bar in current package
+    $bar = 'HgS';              # ok, global declared via pragma
+
+The local() generated a compile-time error because you just touched a global
+name without fully qualifying it.
+
+Because of their special use by sort(), the variables $a and $b are
+exempted from this check.
+
+=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
+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: 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) '...'
+
+=cut