\version "2.15.25"

barDoubled = #(define-music-function (parser location glyph) (string?)
  (define (bar-gap-bar grob)
    (let* (
      (layout (ly:grob-layout grob))
      (weight (ly:output-def-lookup layout 'line-thickness 0.1))
      (raw-gap (ly:grob-property grob 'thin-kern))
      (gap (* raw-gap weight))
      )
      (ly:stencil-combine-at-edge (ly:bar-line::print grob)
        X RIGHT (ly:bar-line::print grob) gap)))
  #{
    \bar $glyph 
    \once \override Score.BarLine #'stencil = $bar-gap-bar
  #}
  )

\relative c'' {
  <<
    { <e b g>4 r \barDoubled "dashed" e4. dis8 }
    \\
    { e,,4 r r2 }
  >>
}