FeatureCollection.pm6

role Bio::Role::FeatureCollection {
    # this role describes methods for accessing Features for a specific instance.
    # implementing classes are considered to contain Bio::Role::Features of some
    # type.

    # Wondering if this and FeatureHolder should be combined for
    # consistency. For instance, it would be nice to have binning available for
    # grabbing features by location.  May be redundant for subfeatures...

    # Would be nice to have iterative methods. Built-in support for Iterators and
    # laziness are planned for perl6 (Iterators are to be a built-in Role):

    # http://design.perl6.org/S07.html

    # Also note that having Grammars that we can attach various Actions to may
    # help this quite a bit.  We'll see as the spec develops...

    has Int $.min_bin;
    has Int $.max_bin;

    our Array of Bio::Role::Feature method get_Features
    (
	:$range? of any(Range | Bio::Role::Range),  # for grabbing features in a range
	Int :$start?,
	Int :$end?,
	Int :$strand?,
	Bool :$contains?,
	Str :$strand_test?,
    )
    {...}

    our Bool method add_Features (:@features of Bio::Role::Feature)
    {...}

    our Array of Bio::Role::Features remove_Features
    (
	:@features? of Bio::Role::Feature,
	:$range? of any(Range | Bio::Role::Range)
    )
    {...}

    our Int method feature_count
    {...}

    our Array of Bio::Role::Feature method get_all_Features
    {...}
}