=head1 NAME
Class::AutoDB::Collection - Compare two collection definitions and
maintain differences
=head1 SYNOPSIS
This is a helper class for Class::AutoDB::Registry to to process
differences between in-memory and saved registries
use Class::AutoDB::CollectionDiff;
use Class::AutoDB::Collection;
my $diff=new Class::AutoDB::CollectionDiff
(-baseline=>$saved, -change=>$in_memory);
if ($diff->is_sub) { # is new collection subset of saved one?
$registry=$saved_registry; # if so, use saved one
} elsif ($diff->is_different) { # else get changes
my %new_keys=$diff->new_keys; #
my @expanded_collections=$diff->expanded_collections;
} else {
die “New collection inconsistent with old”;
}
=head1 DESCRIPTION
This class compares two collection definitions and records their
differences. The first collection is considered the baseline, and
differences are reported relative to it. This class I<does not talk to
the database>.
=cut