package strict;
+$strict::VERSION = "1.03";
+
+my %bitmask = (
+refs => 0x00000002,
+subs => 0x00000200,
+vars => 0x00000400
+);
+
+sub bits {
+ my $bits = 0;
+ 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(@_) : $default_bits;
+}
+
+sub unimport {
+ shift;
+ $^H &= ~ (@_ ? bits(@_) : $default_bits);
+}
+
+1;
+__END__
+
=head1 NAME
strict - Perl pragma to restrict unsafe constructs
use strict "vars";
use strict "refs";
use strict "subs";
- use strict "untie";
use strict;
no strict "vars";
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 four possible things to be
-strict about: "subs", "vars", "refs", and "untie".
+casual programming.) Currently, there are three possible things to be
+strict about: "subs", "vars", and "refs".
=over 6
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
-localized via C<my()> or wasn't fully qualified. Because this is to avoid
+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>.
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
-appears in curly braces or on the left hand side of the "=>" 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"; # just fine: quoted string is always ok
$SIG{PIPE} = \&Plumber; # preferred form
-
-
-=item C<strict untie>
-
-This generates a runtime error if any references to the object returned
-by C<tie> (or C<tied>) still exist when C<untie> is called. Note that
-to get this strict behaviour, the C<use strict 'untie'> statement must
-be in the same scope as the C<untie>. See L<perlfunc/tie>,
-L<perlfunc/untie>, L<perlfunc/tied> and L<perltie>.
-
- use strict 'untie';
- $a = tie %a, 'SOME_PKG';
- $b = tie %b, 'SOME_PKG';
- $b = 0;
- tie %c, PKG;
- $c = tied %c;
- untie %a ; # blows up, $a is a valid object reference.
- untie %b; # ok, $b is not a reference to the object.
- untie %c ; # blows up, $c is a valid object reference.
-
=back
-See L<perlmod/Pragmatic Modules>.
+See L<perlmodlib/Pragmatic Modules>.
+=head1 HISTORY
-=cut
+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.
-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';
- $bits |= 0x00000800 if $sememe eq 'untie';
- }
- $bits;
-}
+Starting with Perl 5.8.1 strict is strict about its restrictions:
+if unknown restrictions are used, the strict pragma will abort with
-sub import {
- shift;
- $^H |= bits(@_ ? @_ : qw(refs subs vars untie));
-}
+ Unknown 'strict' tag(s) '...'
-sub unimport {
- shift;
- $^H &= ~ bits(@_ ? @_ : qw(refs subs vars untie));
-}
-
-1;
+=cut
https://perl5.git.perl.org / perl5.git / blobdiff