summaryrefslogtreecommitdiff
path: root/Master/xemtex/perl/lib/strict.pm
diff options
context:
space:
mode:
authorKarl Berry <karl@freefriends.org>2005-12-28 00:07:27 +0000
committerKarl Berry <karl@freefriends.org>2005-12-28 00:07:27 +0000
commit30dd9f517c9c093ff3319061647a4555264f7914 (patch)
tree0d7a349bf99be5a42cc9c5a80a30f3b7136c4ccd /Master/xemtex/perl/lib/strict.pm
parent08ab8dce83f53b0f915cb66a37bbc8478b22c307 (diff)
trunk
git-svn-id: svn://tug.org/texlive/trunk@9 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/xemtex/perl/lib/strict.pm')
-rw-r--r--Master/xemtex/perl/lib/strict.pm117
1 files changed, 117 insertions, 0 deletions
diff --git a/Master/xemtex/perl/lib/strict.pm b/Master/xemtex/perl/lib/strict.pm
new file mode 100644
index 00000000000..737cb18b1ad
--- /dev/null
+++ b/Master/xemtex/perl/lib/strict.pm
@@ -0,0 +1,117 @@
+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
+ $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 "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
+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 = "1.02";
+
+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;