NAME
    Data::Container - Base class for objects containing a list of items

SYNOPSIS
        package My::Container;
        use base 'Data::Container';
        # ...

        package main;
        my $container = My::Container->new;
        $container->items_push('some_item');

DESCRIPTION
    This class implements a container object. The container can contain any
    object, scalar or reference you like. Typically you would subclass
    Data::Container and implement custom methods for your specific
    container.

    When the container is stringified, it returns the concatenated
    stringifications of its items, each two items joined by two newlines.

METHODS
    "new"
            my $obj = Data::Container->new;
            my $obj = Data::Container->new(%args);

        Creates and returns a new object. The constructor will accept as
        arguments a list of pairs, from component name to initial value. For
        each pair, the named component is initialized by calling the method
        of the same name with the given value. If called with a single hash
        reference, it is dereferenced and its key/value pairs are set as
        described before.

    "clear_items"
            $obj->clear_items;

        Deletes all elements from the array.

    "count_items"
            my $count = $obj->count_items;

        Returns the number of elements in the array.

    "index_items"
            my $element   = $obj->index_items(3);
            my @elements  = $obj->index_items(@indices);
            my $array_ref = $obj->index_items(@indices);

        Takes a list of indices and returns the elements indicated by those
        indices. If only one index is given, the corresponding array element
        is returned. If several indices are given, the result is returned as
        an array in list context or as an array reference in scalar context.

    "items"
            my @values    = $obj->items;
            my $array_ref = $obj->items;
            $obj->items(@values);
            $obj->items($array_ref);

        Get or set the array values. If called without an arguments, it
        returns the array in list context, or a reference to the array in
        scalar context. If called with arguments, it expands array
        references found therein and sets the values.

    "items_clear"
            $obj->items_clear;

        Deletes all elements from the array.

    "items_count"
            my $count = $obj->items_count;

        Returns the number of elements in the array.

    "items_index"
            my $element   = $obj->items_index(3);
            my @elements  = $obj->items_index(@indices);
            my $array_ref = $obj->items_index(@indices);

        Takes a list of indices and returns the elements indicated by those
        indices. If only one index is given, the corresponding array element
        is returned. If several indices are given, the result is returned as
        an array in list context or as an array reference in scalar context.

    "items_pop"
            my $value = $obj->items_pop;

        Pops the last element off the array, returning it.

    "items_push"
            $obj->items_push(@values);

        Pushes elements onto the end of the array.

    "items_set"
            $obj->items_set(1 => $x, 5 => $y);

        Takes a list of index/value pairs and for each pair it sets the
        array element at the indicated index to the indicated value. Returns
        the number of elements that have been set.

    "items_shift"
            my $value = $obj->items_shift;

        Shifts the first element off the array, returning it.

    "items_splice"
            $obj->items_splice(2, 1, $x, $y);
            $obj->items_splice(-1);
            $obj->items_splice(0, -1);

        Takes three arguments: An offset, a length and a list.

        Removes the elements designated by the offset and the length from
        the array, and replaces them with the elements of the list, if any.
        In list context, returns the elements removed from the array. In
        scalar context, returns the last element removed, or "undef" if no
        elements are removed. The array grows or shrinks as necessary. If
        the offset is negative then it starts that far from the end of the
        array. If the length is omitted, removes everything from the offset
        onward. If the length is negative, removes the elements from the
        offset onward except for -length elements at the end of the array.
        If both the offset and the length are omitted, removes everything.
        If the offset is past the end of the array, it issues a warning, and
        splices at the end of the array.

    "items_unshift"
            $obj->items_unshift(@values);

        Unshifts elements onto the beginning of the array.

    "pop_items"
            my $value = $obj->pop_items;

        Pops the last element off the array, returning it.

    "push_items"
            $obj->push_items(@values);

        Pushes elements onto the end of the array.

    "set_items"
            $obj->set_items(1 => $x, 5 => $y);

        Takes a list of index/value pairs and for each pair it sets the
        array element at the indicated index to the indicated value. Returns
        the number of elements that have been set.

    "shift_items"
            my $value = $obj->shift_items;

        Shifts the first element off the array, returning it.

    "splice_items"
            $obj->splice_items(2, 1, $x, $y);
            $obj->splice_items(-1);
            $obj->splice_items(0, -1);

        Takes three arguments: An offset, a length and a list.

        Removes the elements designated by the offset and the length from
        the array, and replaces them with the elements of the list, if any.
        In list context, returns the elements removed from the array. In
        scalar context, returns the last element removed, or "undef" if no
        elements are removed. The array grows or shrinks as necessary. If
        the offset is negative then it starts that far from the end of the
        array. If the length is omitted, removes everything from the offset
        onward. If the length is negative, removes the elements from the
        offset onward except for -length elements at the end of the array.
        If both the offset and the length are omitted, removes everything.
        If the offset is past the end of the array, it issues a warning, and
        splices at the end of the array.

    "unshift_items"
            $obj->unshift_items(@values);

        Unshifts elements onto the beginning of the array.

    "items_set_push"
        Like "items_push()", and it also takes a list of items to push into
        the container, but it doesn't push any items that are already in the
        container (items are compared deeply to determine equality).

    "item_grep"
        Given a package name, it returns those items from the container
        whose "ref()" is equal to that package name.

        For example, your container could contain some items of type
        "My::Item::Foo" and some of type "My::Item::Bar". If you only want a
        list of the items of type "My::Item::Foo", you could use:

            my @foo_items = $container->item_grep('My::Item::Foo');

    "stringify"
        Stringifies the data container by concatenating the items together,
        separated by an empty line.

    "prepare_comparable"
        Adds support for Data::Comparable by autovivifying the container
        items array.

BUGS AND LIMITATIONS
    No bugs have been reported.

    Please report any bugs or feature requests through the web interface at
    <http://rt.cpan.org>.

INSTALLATION
    See perlmodinstall for information and options on installing Perl
    modules.

AVAILABILITY
    The latest version of this module is available from the Comprehensive
    Perl Archive Network (CPAN). Visit <http://www.perl.com/CPAN/> to find a
    CPAN site near you. Or see
    <http://search.cpan.org/dist/Data-Container/>.

AUTHORS
    Marcel Grünauer, "<marcel@cpan.org>"

COPYRIGHT AND LICENSE
    Copyright 2004-2009 by the authors.

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

