76 lines
2.3 KiB
Perl
76 lines
2.3 KiB
Perl
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package vars;
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require 5.002;
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# The following require can't be removed during maintenance
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# releases, sadly, because of the risk of buggy code that does
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# require Carp; Carp::croak "..."; without brackets dying
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# if Carp hasn't been loaded in earlier compile time. :-(
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# We'll let those bugs get found on the development track.
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require Carp if $] < 5.00450;
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sub import {
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my $callpack = caller;
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my ($pack, @imports, $sym, $ch) = @_;
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foreach $sym (@imports) {
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($ch, $sym) = unpack('a1a*', $sym);
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if ($sym =~ tr/A-Za-Z_0-9//c) {
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# time for a more-detailed check-up
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if ($sym =~ /::/) {
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require Carp;
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Carp::croak("Can't declare another package's variables");
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} elsif ($sym =~ /^\w+[[{].*[]}]$/) {
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require Carp;
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Carp::croak("Can't declare individual elements of hash or array");
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} elsif ($^W and length($sym) == 1 and $sym !~ tr/a-zA-Z//) {
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require Carp;
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Carp::carp("No need to declare built-in vars");
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}
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}
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*{"${callpack}::$sym"} =
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( $ch eq "\$" ? \$ {"${callpack}::$sym"}
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: $ch eq "\@" ? \@ {"${callpack}::$sym"}
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: $ch eq "\%" ? \% {"${callpack}::$sym"}
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: $ch eq "\*" ? \* {"${callpack}::$sym"}
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: $ch eq "\&" ? \& {"${callpack}::$sym"}
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: do {
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require Carp;
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Carp::croak("'$ch$sym' is not a valid variable name");
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});
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}
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};
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1;
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__END__
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=head1 NAME
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vars - Perl pragma to predeclare global variable names
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=head1 SYNOPSIS
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use vars qw($frob @mung %seen);
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=head1 DESCRIPTION
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This will predeclare all the variables whose names are
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in the list, allowing you to use them under "use strict", and
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disabling any typo warnings.
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Unlike pragmas that affect the C<$^H> hints variable, the C<use vars> and
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C<use subs> declarations are not BLOCK-scoped. They are thus effective
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for the entire file in which they appear. You may not rescind such
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declarations with C<no vars> or C<no subs>.
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Packages such as the B<AutoLoader> and B<SelfLoader> that delay
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loading of subroutines within packages can create problems with
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package lexicals defined using C<my()>. While the B<vars> pragma
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cannot duplicate the effect of package lexicals (total transparency
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outside of the package), it can act as an acceptable substitute by
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pre-declaring global symbols, ensuring their availability to the
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later-loaded routines.
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See L<perlmodlib/Pragmatic Modules>.
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=cut
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