source: trunk/essentials/dev-lang/perl/lib/constant.pm@ 3310

package constant;

use strict;
use 5.006_00;
use warnings::register;

our($VERSION, %declared);
$VERSION = '1.05';

#=======================================================================

# Some names are evil choices.
my %keywords = map +($_, 1), qw{ BEGIN INIT CHECK END DESTROY AUTOLOAD };

my %forced_into_main = map +($_, 1),
    qw{ STDIN STDOUT STDERR ARGV ARGVOUT ENV INC SIG };

my %forbidden = (%keywords, %forced_into_main);

#=======================================================================
# import() - import symbols into user's namespace
#
# What we actually do is define a function in the caller's namespace
# which returns the value. The function we create will normally
# be inlined as a constant, thereby avoiding further sub calling 
# overhead.
#=======================================================================
sub import {
    my $class = shift;
    return unless @_;                   # Ignore 'use constant;'
    my %constants = ();
    my $multiple  = ref $_[0];

    if ( $multiple ) {
        if (ref $_[0] ne 'HASH') {
            require Carp;
            Carp::croak("Invalid reference type '".ref(shift)."' not 'HASH'");
        }
        %constants = %{+shift};
    } else {
        $constants{+shift} = undef;
    }