Re: bug with baseline-skip in markup-list-commands?

[David Kastrup]

Thomas Morley <address@hidden> writes:

> Hi,
>
> look at the following code (png attached)
>
> \version "2.19.24"
>
> mrkpI =
> \markup
>  {
>   \override #'(baseline-skip . 10)
>   \column \box { "xy" "xy" "xy" "xy" }
>  }
>
> mrkpII =
> \markuplist
>  {
>   \override-lines #'(baseline-skip . 10)
>   \column-lines \box { "xy" "xy" "xy" "xy" }
>  }
>
> \markup \line { \box \mrkpI \box \column \mrkpII }
>
>
> The markup-list-version for baseline-skip adds space even above top
> and below bottom line.
> Responsible is 'space-lines' from define-markup-commands.scm.
> (used in justified-lines, wordwrap-lines, column-lines)
>
> Is this really intended?

I think so.

> At least the description for column-lines says different:
> "[...] @code{baseline-skip} determines the space between (sic!) each
> markup in @var{args}"
>
> If not intended (that's what I guess), I'll provide a patch.

Well, part of the problem is that \column-lines is simply a misleading
name since the resulting markups are not actually arranged in a column
or otherwise.  You write \column \mrkpII here, but \line \mrkpII is
equally valid.  And so is

\column { \mrkpII \mrkpII }

So \column-lines clearly serves a need that is not easily provided
otherwise.  It's not used much in LilyPond's codebase though.  Most use
appears to be in input/regression/markup-first-visible.ly where the
proposed behavior would appear to lead to strange results (as
column-lines is indeed not used for creating a column there).

I agree that name and documentation are less than helpful, maybe leading
to its underuse.  Is there a good use case for the proposed behavior as
well or is this just a matter of code/doc hygiene for you?

-- 
David Kastrup