undo change#5506; add patch to make blank line warnings optional

[perl5.git] / lib / vars.pm

diff --git a/lib/vars.pm b/lib/vars.pm
index b951929..6ae5373 100644 (file)
--- a/lib/vars.pm
+++ b/lib/vars.pm
@@ -1,39 +1,79 @@
 package vars;
 
-=head1 NAME
-
-vars - Perl pragma to predeclare global variable names
+require 5.002;
 
-=head1 SYNOPSIS
-
-    use vars qw($frob @mung %seen);
-
-=head1 DESCRIPTION
-
-This will predeclare all the variables whose names are 
-in the list, allowing you to use them under "use strict", and
-disabling any typo warnings.
-
-See L<perlmod/Pragmatic Modules>.
-
-=cut
-require 5.000;
-use Carp;
+# The following require can't be removed during maintenance
+# releases, sadly, because of the risk of buggy code that does
+# require Carp; Carp::croak "..."; without brackets dying
+# if Carp hasn't been loaded in earlier compile time. :-(
+# We'll let those bugs get found on the development track.
+require Carp if $] < 5.00450;
 
 sub import {
     my $callpack = caller;
     my ($pack, @imports, $sym, $ch) = @_;
     foreach $sym (@imports) {
-       croak "Can't declare another package's variables" if $sym =~ /::/;
         ($ch, $sym) = unpack('a1a*', $sym);
+       if ($sym =~ tr/A-Za-z_0-9//c) {
+           # time for a more-detailed check-up
+           if ($sym =~ /::/) {
+               require Carp;
+               Carp::croak("Can't declare another package's variables");
+           } elsif ($sym =~ /^\w+[[{].*[]}]$/) {
+               require Carp;
+               Carp::croak("Can't declare individual elements of hash or array");
+           } elsif ($^W and length($sym) == 1 and $sym !~ tr/a-zA-Z//) {
+               require Carp;
+               Carp::carp("No need to declare built-in vars");
+           }
+       }
         *{"${callpack}::$sym"} =
           (  $ch eq "\$" ? \$   {"${callpack}::$sym"}
            : $ch eq "\@" ? \@   {"${callpack}::$sym"}
            : $ch eq "\%" ? \%   {"${callpack}::$sym"}
            : $ch eq "\*" ? \*   {"${callpack}::$sym"}
            : $ch eq "\&" ? \&   {"${callpack}::$sym"}
-           : croak "'$ch$sym' is not a valid variable name\n");
+           : do {
+               require Carp;
+               Carp::croak("'$ch$sym' is not a valid variable name");
+            });
     }
 };
 
 1;
+__END__
+
+=head1 NAME
+
+vars - Perl pragma to predeclare global variable names (obsolete)
+
+=head1 SYNOPSIS
+
+    use vars qw($frob @mung %seen);
+
+=head1 DESCRIPTION
+
+NOTE: The functionality provided by this pragma has been superseded
+by C<our> declarations, available in Perl v5.6.0 or later.  See
+L<perlfunc/our>.
+
+This will predeclare all the variables whose names are 
+in the list, allowing you to use them under "use strict", and
+disabling any typo warnings.
+
+Unlike pragmas that affect the C<$^H> hints variable, the C<use vars> and
+C<use subs> declarations are not BLOCK-scoped.  They are thus effective
+for the entire file in which they appear.  You may not rescind such
+declarations with C<no vars> or C<no subs>.
+
+Packages such as the B<AutoLoader> and B<SelfLoader> that delay
+loading of subroutines within packages can create problems with
+package lexicals defined using C<my()>. While the B<vars> pragma
+cannot duplicate the effect of package lexicals (total transparency
+outside of the package), it can act as an acceptable substitute by
+pre-declaring global symbols, ensuring their availability to the
+later-loaded routines.
+
+See L<perlmodlib/Pragmatic Modules>.
+
+=cut