> Le 10 juil. 2022 à 13:47, Werner LEMBERG <w...@gnu.org> a écrit :
>
>
> The documentation of `ly:context-property` is as follows.
>
> -- Function: ly:context-property context sym def
>
> Return the value for property SYM in CONTEXT. If DEF is given,
> and property value is ‘'()’, return DEF.
>
> I have a use case where I want to say
>
> ```
> \set SYM = #'()
> ```
>
> i.e., I explicitly want to override the default DEF with an empty
> list. How can I do that?
As a user, if the code is written that way, you have no proper solution. Yes,
that’s a bit sad. (If the property is an alist, though, you can use a dummy
alist with a key that is not in the set of keys the code looks for, e.g. a
string if the alist is supposed to map numbers to something.)
As a developer, you should not write the code that way. I suspect you ask this
in the context of your figured bass code, right? You need to put the default in
the definition of the context in ly/engraver-init.ly so that you don’t need to
use the third argument of ly:context-property. That also makes the default
appear in the IR.
Jean
