Ok, suppose we have a policy-based class Foo, and a policy P: template <typename Policy> class Foo { // ... }; struct P { template <typename T> struct apply { typedef policy type; }; }; Now, my understanding is that we can use Lambda so that we can invoke Foo this way: Foo<P> f; Or define P in this way: template <typename T> struct P { // policy }; and call Foo this way: Foo<P<_> > f; But if I require that everyone define P in the first way, then Lambda should not be necessary, is that correct? Is there still a reason to use Lambda in that case? Dave --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.683 / Virus Database: 445 - Release Date: 5/12/2004