Tuplet ratio-notation

[Jesse Engle]

Hi everyone.

For those of you that don't know, ratio-notation specifies both the 
number of beats in a tuplet and the number of beats that would normally 
be played without a tuplet. For instance a tuplet of 5 sixteenth notes 
would be notated not as the normal "5", but "5:4", signaling that there 
are 5 sixteenths in the place of (":") 4 sixteenths.

I was told on the lilypond-devel mailing list that the following line 
would provide ratio-notation for tuplets:

\override TupletNumber #'text = #tuplet-number::calc-fraction-text

This does not seem to work. How can I accomplish this?

Jesse Engle