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62 NOTE: The functionality provided by this pragma has been superseded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