105 lines
2.2 KiB
Perl
105 lines
2.2 KiB
Perl
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
|
|
declared via 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;
|
|
use vars qw/ $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.
|
|
|
|
=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<perlmodlib/Pragmatic Modules>.
|
|
|
|
|
|
=cut
|
|
|
|
$strict::VERSION = "1.01";
|
|
|
|
my %bitmask = (
|
|
refs => 0x00000002,
|
|
subs => 0x00000200,
|
|
vars => 0x00000400
|
|
);
|
|
|
|
sub bits {
|
|
my $bits = 0;
|
|
foreach my $s (@_){ $bits |= $bitmask{$s} || 0; };
|
|
$bits;
|
|
}
|
|
|
|
sub import {
|
|
shift;
|
|
$^H |= bits(@_ ? @_ : qw(refs subs vars));
|
|
}
|
|
|
|
sub unimport {
|
|
shift;
|
|
$^H &= ~ bits(@_ ? @_ : qw(refs subs vars));
|
|
}
|
|
|
|
1;
|