package pudu;
use strict;
use warnings;

use constant Exportables => {
    has => { -as => 'has' },
    new => { -as => 'new' }
};

my @attrs = ();

sub _exportTo {
    no strict qw[ refs ];
    *{ $_[0] . '::' . $_[ 1 ] } = $_[ 2 ];
}

sub new {
    my $class = shift;
    die "Uneven attribute list (Missing value?(use 'undef')" if @_ & 1;
    my %args = @_;
    return bless \@attrs, $class;
}

sub has {
    my $package = caller;
    my $name = shift;
    my %attr = @_;
    $attrs[ @attrs ] = \%attr;
    my $slot = eval qq[ sub(){ ${ \$#attrs } } ];
    _exportTo(
        $package, $name,
        sub :lvalue {
            $_[ 0 ][ &$slot ]{ trigger }->( $_[ 0 ], $_[ 1 ] )
                if $_[ 0 ][ &$slot ]{ trigger };
            $_[ 0 ][ &$slot ]
        }
    );
}

sub import {
    my $class = shift;
    die "Uneven parameter list (Symbol without alias?)" if @_ & 1;
    my %args = ( %{ +Exportables }, @_ );

    my %exports;
    @exports{ keys %{ +Exportables } } = delete @args{ keys %{ +Exportables } };

    warn "Unknown export(s) @{[ keys %args ]} ignored" if %args;

    my $package = caller;

    while( my( $export, $alias ) = each %exports ) {
        _exportTo( $package, $alias->{ -as }, \&$export );
    }
}

1;