package Class::Struct;

## See POD after __END__

use 5.006_001;

use strict;
use warnings::register;
our(@ISA, @EXPORT, $VERSION);

use Carp;

require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(struct);

$VERSION = '0.63';

## Tested on 5.002 and 5.003 without class membership tests:
my $CHECK_CLASS_MEMBERSHIP = ($] >= 5.003_95);

my $print = 0;
sub printem {
    if (@_) { $print = shift }
    else    { $print++ }
}

{
    package Class::Struct::Tie_ISA;

    sub TIEARRAY {
        my $class = shift;
        return bless [], $class;
    }

    sub STORE {
        my ($self, $index, $value) = @_;
        Class::Struct::_subclass_error();
    }

    sub FETCH {
        my ($self, $index) = @_;
        $self->[$index];
    }

    sub FETCHSIZE {
        my $self = shift;
        return scalar(@$self);
    }

    sub DESTROY { }
}

sub import {
    my $self = shift;

    if ( @_ == 0 ) {
      $self->export_to_level( 1, $self, @EXPORT );
    } elsif ( @_ == 1 ) {
	# This is admittedly a little bit silly:
	# do we ever export anything else than 'struct'...?
      $self->export_to_level( 1, $self, @_ );
    } else {
      goto &struct;
    }
}

sub struct {

    # Determine parameter list structure, one of:
    #   struct( class => [ element-list ])
    #   struct( class => { element-list })
    #   struct( element-list )
    # Latter form assumes current package name as struct name.

    my ($class, @decls);
    my $base_type = ref $_[1];
    if ( $base_type eq 'HASH' ) {
        $class = shift;
        @decls = %{shift()};
        _usage_error() if @_;
    }
    elsif ( $base_type eq 'ARRAY' ) {
        $class = shift;
        @decls = @{shift()};
        _usage_error() if @_;
    }
    else {
        $base_type = 'ARRAY';
        $class = (caller())[0];
        @decls = @_;
    }

    _usage_error() if @decls % 2 == 1;

    # Ensure we are not, and will not be, a subclass.

    my $isa = do {
        no strict 'refs';
        \@{$class . '::ISA'};