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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;
use warnings::register;
require strict;
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+[[{].*[]}]$/) {
require Carp;
Carp::croak("Can't declare individual elements of hash or array");
} elsif (warnings::enabled() and length($sym) == 1 and $sym !~ tr/a-zA-Z//) {
warnings::warn("No need to declare built-in vars");
} elsif ( $^H &= strict::bits('vars') ) {
Carp::croak("'$ch$sym' is not a valid variable name under strict vars");
}
}
*{"${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$sym' is not a valid variable name");
});
}
};
1;
__END__
=head1 NAME
vars - Perl pragma to predeclare global variable names (obsolete)
=head1 SYNOPSIS
use vars qw($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NOTE: The functionality provided by this pragma has been superseded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
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