"filtered view" upon lists?

[Wildemar Wildenburger]

Hi there :)

I don't know how else to call what I'm currently implementing: An object 
that behaves like a list but doesn't store it's own items but rather 
pulls them from a larger list (if they match a certain criterion).
Changes to the filter are instantly reflected in the underlying list.
Clear enough?

Ok, so I figured that this is generic enough to be found in some 
standard module already (I've had this often enough: Painfully 
implementing s/th and then finding it in the libs some weeks later.).

Any pointers?

c.u.
wildemar