package vars; require 5.002; # 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 $sym (@imports) { ($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}::$sym"} : do { require Carp; Carp::croak("'$ch$sym' is not a valid variable name"); }); } }; 1; __END__ =head1 NAME vars - Perl pragma to predeclare global variable names =head1 SYNOPSIS use vars qw($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. Unlike pragmas that affect the C<$^H> hints variable, the C and C 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 or C. Packages such as the B and B that delay loading of subroutines within packages can create problems with package lexicals defined using C. While the B 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. =cut