package strict;
+$strict::VERSION = "1.10";
+
+# Verify that we're called correctly so that strictures will work.
+unless ( __FILE__ =~ /(^|[\/\\])\Q${\__PACKAGE__}\E\.pmc?$/ ) {
+ # Can't use Carp, since Carp uses us!
+ my (undef, $f, $l) = caller;
+ die("Incorrect use of pragma '${\__PACKAGE__}' at $f line $l.\n");
+}
+
+my ( %bitmask, %explicit_bitmask );
+
+BEGIN {
+ %bitmask = (
+ refs => 0x00000002,
+ subs => 0x00000200,
+ vars => 0x00000400,
+ );
+
+ %explicit_bitmask = (
+ refs => 0x00000020,
+ subs => 0x00000040,
+ vars => 0x00000080,
+ );
+
+ 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 (@_) {
+ if (exists $bitmask{$s}) {
+ $^H |= $explicit_bitmask{$s};
+
+ $bits |= $bitmask{$s};
+ }
+ else {
+ push @wrong, $s;
+ }
+ }
+ if (@wrong) {
+ require Carp;
+ Carp::croak("Unknown 'strict' tag(s) '@wrong'");
+ }
+ $bits;
+}
+
+sub import {
+ shift;
+ $^H |= @_ ? &bits : all_bits | all_explicit_bits;
+}
+
+sub unimport {
+ shift;
+
+ if (@_) {
+ $^H &= ~&bits;
+ }
+ else {
+ $^H &= ~all_bits;
+ $^H |= all_explicit_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";
=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 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
-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
+ $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; # 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.
+ $SIG{PIPE} = Plumber; # blows up
+ $SIG{PIPE} = "Plumber"; # fine: quoted string is always ok
+ $SIG{PIPE} = \&Plumber; # preferred form
=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));
-}
+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.
-1;
+=cut
https://perl5.git.perl.org / perl5.git / blobdiff