1package vars; 2 3require 5.002; 4 5# The following require can't be removed during maintenance 6# releases, sadly, because of the risk of buggy code that does 7# require Carp; Carp::croak "..."; without brackets dying 8# if Carp hasn't been loaded in earlier compile time. :-( 9# We'll let those bugs get found on the development track. 10require Carp if $] < 5.00450; 11 12use warnings::register; 13require strict; 14 15sub import { 16 my $callpack = caller; 17 my ($pack, @imports, $sym, $ch) = @_; 18 foreach $sym (@imports) { 19 ($ch, $sym) = unpack('a1a*', $sym); 20 if ($sym =~ tr/A-Za-z_0-9//c) { 21 # time for a more-detailed check-up 22 if ($sym =~ /::/) { 23 require Carp; 24 Carp::croak("Can't declare another package's variables"); 25 } elsif ($sym =~ /^\w+[[{].*[]}]$/) { 26 require Carp; 27 Carp::croak("Can't declare individual elements of hash or array"); 28 } elsif (warnings::enabled() and length($sym) == 1 and $sym !~ tr/a-zA-Z//) { 29 warnings::warn("No need to declare built-in vars"); 30 } elsif ( $^H &= strict::bits('vars') ) { 31 Carp::croak("'$ch$sym' is not a valid variable name under strict vars"); 32 } 33 } 34 *{"${callpack}::$sym"} = 35 ( $ch eq "\$" ? \$ {"${callpack}::$sym"} 36 : $ch eq "\@" ? \@ {"${callpack}::$sym"} 37 : $ch eq "\%" ? \% {"${callpack}::$sym"} 38 : $ch eq "\*" ? \* {"${callpack}::$sym"} 39 : $ch eq "\&" ? \& {"${callpack}::$sym"} 40 : do { 41 require Carp; 42 Carp::croak("'$ch$sym' is not a valid variable name"); 43 }); 44 } 45}; 46 471; 48__END__ 49 50=head1 NAME 51 52vars - Perl pragma to predeclare global variable names (obsolete) 53 54=head1 SYNOPSIS 55 56 use vars qw($frob @mung %seen); 57 58=head1 DESCRIPTION 59 60NOTE: The functionality provided by this pragma has been superseded 61by C<our> declarations, available in Perl v5.6.0 or later. See 62L<perlfunc/our>. 63 64This will predeclare all the variables whose names are 65in the list, allowing you to use them under "use strict", and 66disabling any typo warnings. 67 68Unlike pragmas that affect the C<$^H> hints variable, the C<use vars> and 69C<use subs> declarations are not BLOCK-scoped. They are thus effective 70for the entire file in which they appear. You may not rescind such 71declarations with C<no vars> or C<no subs>. 72 73Packages such as the B<AutoLoader> and B<SelfLoader> that delay 74loading of subroutines within packages can create problems with 75package lexicals defined using C<my()>. While the B<vars> pragma 76cannot duplicate the effect of package lexicals (total transparency 77outside of the package), it can act as an acceptable substitute by 78pre-declaring global symbols, ensuring their availability to the 79later-loaded routines. 80 81See L<perlmodlib/Pragmatic Modules>. 82 83=cut 84