Template design with required type parameters?

[Charles D Hixson]

Is it possible to design a template that requires, at compile 
time, that it's parameters be of a particular type?

I.e., that they include a certain class or interface among 
their ancestry?

What I'm actually contemplating is a kind of "comparable" 
interface that I want to require one of the parameters to the 
Template to have.  I haven't decided whether there should be 
more than one parameter, partially that depends on just how I 
should approach this.  (I've also considered just skipping 
templates altogether and doing the entire thing through normal 
class inheritance...which would work, but everyone seems to be 
pushing templates right now.)

It's also true that I may just end up doing "duck typing" if 
the implementation gets too cumbersome.

I'm not really after ultimate run-time efficiency, I'd prefer 
clarity combined with "good" efficiency.