I'd argue that it's really two functions: * One to do the lookup and potentially explode; this always takes an argument. * A second to provide the default. H

I'd argue that it's really two functions: * One to do the lookup and potentially explode; this always takes an argument. * A second to provide the default. Have the caller call the appropriate one. User provides params[:search] (or some other "explicitly trying to search"), then call the first. If not, call the latter.