Using a search path for templates?

For several parts of my views I have generic partials. In some cases I,
however, I need to use more specific partials. Generally, I handle this
through configuration in the controllers where this applies. For this I
assign the paths of the default partials to instance variables in the
ApplicationController. When I need more specific partials, I re-assign
the instance variable with their path in a concrete controller.

This approach works, but I'd like to have it more comfy and DRYer. What
I want is a way to put the generic partials into /app/views/default and
have them used unless there are more specific partials
in /app/views/somethings.