[luatex] First question: Retrieve *family* name of a font / the three main families

[Urs Liska]

Am 20. Januar 2018 20:29:04 MEZ schrieb "Br. Samuel Springuel" <rpspringuel at gmail.com>:
>On 1/20/18 11:36 AM, Ulrike Fischer wrote:
>> Well as I already wrote on tex.SX it is rather unclear what you mean
>> by family and how you want to use it.
>
>The goal is to be able to pass the information to another program, 
>LilyPond, and use it to set the fonts there so that there is some 
>consistency in the look of documents which mix results from LuaTeX and 
>LilyPond (and it happens automatically).
>
>Unlike LuaTex (and other TeX flavors) which permit mixing fonts as 
>you've indicated, LilyPond doesn't.  Instead it defines three font 
>groups: roman, sans, and typewriter.  Within those groups changes in 
>weight, shape, etc. are automatically done within the same font family.
>

Indeed. LilyPond's *text* setting capabilities are frustratingly simple. 

>I.e. if I define the roman font to be Century Schoolbook, then the bold
>
>text will always be the Century Schoolbook-Bold.  If I define it to be 
>Arial then bold will be Arial Bold.  So far as I know, there is no way 
>to do something like what you indicate is possible in LuaTeX within 
>LilyPond.  In this respect, selecting the font in LilyPond is like 
>selecting a font in a "dumb" program like Word or OpenOffice.
>
>When Urs says he wants the font family, then, he's looking for that 
>primary name which would allow a "dumb" program to select the normal, 
>bold, italic, etc. font varieties from that same family.

Yes, exactly. I need basically the font specified in the mandatory argument, and from this the "family" name (but I have seen in this thread how to get that information from Lua). 

Urs