If you want values in @to_be_ordered that are not in %order to be put at the end of the list, you might try something like this:

my @sorted =
   ((sort {$order{$a} <=> $order{$b}}
   grep {exists $order{$_}} @to_be_ordered),
   grep {not exists $order{$_}} @to_be_ordered);
[download]

Of course, this runs through @to_be_ordered twice, which is inefficient. So you might use two temporary arrays:

my (@exists, @not_exists);
push @{exists $order{$_} ? \@exists : \@not_exists }, $_ for @to_be_or
+dered;
my @sorted = ((sort {$order{$a} <=> $order{$b}} @exists), @not_exists)
+;
[download]

-- Mike

--
just,my${.02}