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- package strict;
- $strict::VERSION = "1.09";
- # Verify that we're called correctly so that strictures will work.
- unless ( __FILE__ =~ /(^|[\/\\])\Q${\__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
- =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 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 $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
- 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"; # 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
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