You'd have to say "look at the sort listing functions" because you would have to have another one for ```extended_index_attrs()```.  Not only that but if one of the attributes needed additional configuration than the rest then your once simple list of attributes isn't so simple any longer.

I personally believe a comment provides more documentation without adding an additional unnecessary level of complexity.  I did group the sort attributes together though.  This is supposed to be imperative configuration after all.