Re: Non-standard ledger lines and articulations collisions

[Paul Morris]

On 01/10/2018 10:57 AM, David Kastrup wrote:

> You are missing the difference between
> ly:side-position-interface::y-aligned-side and
> side-position-interface::y-aligned-side .
>
> The latter is defined in scm/output-lib.scm as
>
> (define-public side-position-interface::y-aligned-side
>    (ly:make-unpure-pure-container
>     ly:side-position-interface::y-aligned-side
>     ly:side-position-interface::pure-y-aligned-side))
>
> > So am I missing something or are the docs off for Script.Y-offset?
> The docs are autogenerated and cannot be off with regard to listed
> default values.
>
> > Is a call to "(ly:side-position-interface::y-aligned-side grob)"
> > actually the default call to use?
> You are better off with
> (ly:pure-call side-position-interface::y-aligned-side grob start end)
> or
> (ly:unpure-call side-position-interface::y-aligned-side grob)
> depending on what you need.
>
> Or of course calling ly:side-position-interface::y-aligned-side and
> ly:side-position-interface::pure-y-aligned-side directly.

Thank you David!  That clears up most of my confusion.  Should have 
realized there was a difference between those two procedures.  I'd still 
like to look further into what's going on with the unpure-pure-container 
stuff, as I currently only have a vague sense of it.  Then maybe I'll 
have a better handle on whether to use the pure or unpure call for this 
case. (Or, I wonder, if it would make sense to do wrapped/custom 
versions of both and then combine them with 
ly:make-unpure-pure-container , so it more closely parallels the default 
situation?)

Thanks again,
Paul