Lilypond: Convenient code for basso continuo horizontal lines?

Question

In basso continuo you sometimes want to place horizontal lines to indicate stable harmony. This is done in LilyPond using \bassFigureExtendersOn:

\version "2.18.2"

\score {
    <<
        \new Staff {
            <b' g' f'>4
            <c'' g' e'>4
            <b' g' d'>2
            |
            <b' g' f'>4
            <c'' g' e'>4
            <d'' g' d'>2
        }
        \new Staff { \clef bass
            d4
            e8 c
            g2
            |
            d4
            e8 c
            b,2
        }
        \figures {
            \bassFigureExtendersOn
            <4 3>4
            <6>8 <6> % <- this is problematic
            r2
            |
            <4 3>4
            <6>8 <6> % <- this is problematic
            <6\!>2 % <- this is problematic
        }
    >>
}

However, this has two drawbacks:

• the <6> for c is incorrect technically-speaking (it will show rubbish things if \bassFigureExtendersOn is not used.
• the b in the second bar needs \! to show the proper thing.

So I wonder whether it's possible to activate an extender manually. Something like <6>8~ q would be great, because while the c shouldn't have a <6>, this would already make the code clear. (This would basically have the opposite effect of \!.)

Answer 1

In Lilypond there is no off-the-shelf way of doing this. However, these things don’t strike me as problematic. The extra 6 on the c here does not mean that the chord is in first inversion, it simply tells the engraver how far to print the line - i.e. it tells it where to ‘tie’ to. It’s not harmonic semantic content, it’s a markup instruction. Using q here would be the same as writing the 6 so I’m not sure how that helps conceptually - nor does it save much typing. q would also not help if the next figure was <6 x> and needed an extender. \bassFigureExtendersOn effectively puts a ~ after each <> If you don’t want to use \! then just turn the extenders on and off as required (fwiw this is how I deal with extenders).