How to select a style based on the controller?

I know I’ve seen this somewhere before, but my friend Google and I just can’t seem to recall where.

I would like to change the style of a link (in my application layout) based upon which controller is currently active.

This is what I have, which doesn’t work:

<%= link_to “Part”, part_path, :class => == “parts” ? ‘selectedmenu’ : ‘unselectedmenu’ %>

I’m sure I’ve seen this sort of construct in the past, but I can’t recall how to construct it. Specifically, this bombs because name is undefined. I can probably figure that one out myself. More generally, is there a nice helper method defined to select a specific class based on the controller?