predicate_type( &some_predicate ) );
mi.add_sorted_index( index_id++, MyIndex::sorted_index_predicate_type( &some_other_predicate ) );

So basically, add indices at runtime, to take advantage of multi_index's great features, such
as projection, index updating on modification, etc.

My use case, if it's relevant, is to expose multi_index behaviour on objects from a dll.
Where obviously the calling module can't specify at compile time the required indices.

Is this a sensible addition to multi-index, or is it best implement using other mechanisms.
(Having to re-implement many of the great features of multi-index doesn't seem desireable.)

Neil