lib/perl5/5.8.8/vars.pm

   1 package vars;
   2
   3 use 5.006;
   4
   5 our $VERSION = '1.01';
   6
   7 use warnings::register;
   8 use strict qw(vars subs);
   9
  10 sub import {
  11     my $callpack = caller;
  12     my ($pack, @imports) = @_;
  13     my ($sym, $ch);
  14     foreach (@imports) {
  15         if (($ch, $sym) = /^([\$\@\%\*\&])(.+)/) {
  16             if ($sym =~ /\W/) {
  17                 # time for a more-detailed check-up
  18                 if ($sym =~ /^\w+[[{].*[]}]$/) {
  19                     require Carp;
  20                     Carp::croak("Can't declare individual elements of hash or array");
  21                 } elsif (warnings::enabled() and length($sym) == 1 and $sym !~ tr/a-zA-Z//) {
  22                     warnings::warn("No need to declare built-in vars");
  23                 } elsif  (($^H &= strict::bits('vars'))) {
  24                     require Carp;
  25                     Carp::croak("'$_' is not a valid variable name under strict vars");
  26                 }
  27             }
  28             $sym = "${callpack}::$sym" unless $sym =~ /::/;
  29             *$sym =
  30                 (  $ch eq "\$" ? \$$sym
  31                  : $ch eq "\@" ? \@$sym
  32                  : $ch eq "\%" ? \%$sym
  33                  : $ch eq "\*" ? \*$sym
  34                  : $ch eq "\&" ? \&$sym
  35                  : do {
  36                      require Carp;
  37                      Carp::croak("'$_' is not a valid variable name");
  38                  });
  39         } else {
  40             require Carp;
  41             Carp::croak("'$_' is not a valid variable name");
  42         }
  43     }
  44 };
  45
  46 1;
  47 __END__
  48
  49 =head1 NAME
  50
  51 vars - Perl pragma to predeclare global variable names (obsolete)
  52
  53 =head1 SYNOPSIS
  54
  55     use vars qw($frob @mung %seen);
  56
  57 =head1 DESCRIPTION
  58
  59 NOTE: For variables in the current package, the functionality provided
  60 by this pragma has been superseded by C<our> declarations, available
  61 in Perl v5.6.0 or later.  See L<perlfunc/our>.
  62
  63 This will predeclare all the variables whose names are
  64 in the list, allowing you to use them under "use strict", and
  65 disabling any typo warnings.
  66
  67 Unlike pragmas that affect the C<$^H> hints variable, the C<use vars> and
  68 C<use subs> declarations are not BLOCK-scoped.  They are thus effective
  69 for the entire file in which they appear.  You may not rescind such
  70 declarations with C<no vars> or C<no subs>.
  71
  72 Packages such as the B<AutoLoader> and B<SelfLoader> that delay
  73 loading of subroutines within packages can create problems with
  74 package lexicals defined using C<my()>. While the B<vars> pragma
  75 cannot duplicate the effect of package lexicals (total transparency
  76 outside of the package), it can act as an acceptable substitute by
  77 pre-declaring global symbols, ensuring their availability to the
  78 later-loaded routines.
  79
  80 See L<perlmodlib/Pragmatic Modules>.
  81
  82 =cut