% 2.19.8 works, 2.19.15 doesn’t
\version "2.19.16"
\paper { #(set-paper-size "a10" 'landscape) }
\header { tagline = ##f }

% permits the y-offset argument to be omitted
off = #(define-music-function (parser location x y ev) (number? (number? #f) ly:music?)
         #{ -\tweak X-offset $x
            $(if
              y
              #{ -\tweak Y-offset $y $ev #}
              #{ $ev #})
         #})

\score {
  { c'-\off 0 1 \f }
  \layout {
    \context { \Voice
               \dynamicUp
               \override DynamicLineSpanner.outside-staff-priority = ##f }
  }
}